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Associate Professor Rob Duffield

Biography

Associate Professor Rob Duffield is part of the Sport and Exercise Discipline Group in the Faculty of Health at UTS and a core member of the university’s Health Services and Practice unit. His research focuses on performance and recovery aspects of sports science. In particular, Rob investigates pre- and post-cooling for exercise in the heat, the effects of travel and sleep on recovery, and the efficacy of various recovery techniques.

Rob’s research is conducted in collaboration with major Australian sports, including several football codes, tennis and cricket. He also investigates the role of exercise and sport in the prevention of chronic diseases, such as type 2 diabetes and cardiovascular disease amongst sedentary populations, including Indigenous Australians and smokers.

Image of Rob Duffield
Associate Professor, Faculty of Health
Core Member, CHSP - Health Services and Practice
PhD (UWA), PhD Philosopy
 
Phone
+61 2 9514 5294

Research Interests

Research expertise:

  • Sports science (performance, injury and recovery)
  • Exercise for health (exercise and chronic systemic inflammation)
Can supervise: Yes

Areas of research supervision:

  • Team sports performance
  • Pre-cooling and exercise in the heat
  • Travel, sleep and recovery techniques
  • Injury
  • Exercise and chronic systemic inflammation
  • Indigenous health

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Chapters

Duffield, R. & Kalkhoven, J. 2016, 'Effects of Compression Garments in Strength, Power and Speed Based Exercise' in Engel, F. & Sperlich, B. (eds), Compression Garments in Sports: Athletic Performance and Recovery, Springer International Publishing, pp. 63-78.
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Duffield, R., Allen, N.G. & Mendham, A.E. 2016, 'The health benefits of rugby- specific small-sided games for sedentary populations' in Science and Football VIII: The Proceedings of the Eighth World Congress on Science and Football.
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Couturier, A. & Duffield, R. 2013, 'Compression Garments' in Hausswirth, C. & Mujika, I. (eds), Recovery for Performance in Sport, Human Kinetics, USA, pp. 135-144.
The ability to tolerate and recover from physical exertion during athletic activity is noted as an integral component of adaptation and performance enhancement (Barnett 2006). Media that assist postexercise recovery by improving skeletal blood flow in an attempt to improve muscle recovery are popular (Barnett 2006; Vaile et al. 2011). The training and competition demands of high-performance sport can contribute to chronic stress on the cardiovascular and musculoskeletal systems, consequently leading to deterioration of the venous system (Couzan 2006). Based on these demands, various manufacturers have developed compression garments for use by athletes to assist performance and to hasten postexercise recovery. Such technology has been widely adopted by athletes who expect substantial gains in terms of performance and quality of recovery in many sporting disciplines.
Le Muer, Y., Duffield, R. & Skein, M. 2013, 'Sleep' in Hausswirth, C. & Mujika, I. (eds), Recovery for Performance in Sport, Human Kinetics, USA, pp. 99-110.
Sleep is a naturally recurring state that involves the controlled and regulated loss of consciousness, without concurrent loss of sensory perception (Beersma 1998). The process of sleep occurs at regular intervals throughout a 24 h cycle, with the development of sleep accompanied by a gradual reduction in muscle tone and explicit loss of conscious control of physiological regulation (Frank 2006). Sleep can be distinguished from unconsciousness (i.e., a coma) due to the continued control over reflexes, the ability to awake from the loss of consciousness (i.e., sleepers can open their eyes), and the ability to react to speech, touch, or any other external stimuli.
Duffield, R. & Coutts, A.J. 2011, 'Fatigue and the regulation of exercise intensity during team sport matches' in Marino, F. (ed), Regulation of Fatigue in Exercise, Nova Science Publishers, Inc., New York, pp. 117-136.
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Despite the engaging discussion concerning the mechanisms of fatigue during exercise, one common theme seems apparent; that the underlying mechanisms are intensity and duration dependent. As expected, the debate regarding the definition, presence and mechanisms of exercise-induced fatigue centres heavily on findings of laboratory investigations. However, presently there is little evidence from ecologically valid, field-based settings to support this laboratory evidence. From the view of the Exercise and Sports Sciences, a central tenant of the research into the mechanisms of fatigue is to transfer the findings back to an applied setting to understand exercise performance in the field. Accordingly, many laboratory studies have investigated mechanisms responsible for the amelioration or termination of exercise performance. However, particularly for team sports, the poor ecological validity of exercise protocols used restricts application of the findings to the field.
Duffield, R. 2010, 'Pre- and post-exercise cooling strategies to aid exercise performance and assist recovery' in Hauswirth, C. (ed), In Recuperation et performance en sport, INSEP Publications, France, pp. 371-377.
Duffield, R. 2010, 'Compression garments as a performance aid and post-exercise recovery tool' in Hauswirth, C. (ed), In Recuperation et performance en sport, France, pp. 317-323.

Journal articles

Schmit, C., Le Meur, Y., Duffield, R., Robach, P., Oussedik, N., Coutts, A.J. & Hausswirth, C. 2017, 'Heat-acclimatization and pre-cooling: a further boost for endurance performance?', Scandinavian Journal of Medicine and Science in Sports, vol. 27, no. 1, pp. 55-65.
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To determine if pre-cooling (PC) following heat-acclimatization (HA) can further improve self-paced endurance performance in the heat, 13 male triathletes performed two 20-km cycling time-trials (TT) at 35 °C, 50% relative humidity, before and after an 8-day training camp, each time with (PC) or without (control) ice vest PC. Pacing strategies, physiological and perceptual responses were assessed during each TT. PC and HA induced moderate (+10 ± 18 W; effect size [ES] 4.4 ± 4.6%) and very large (+28 ± 19 W; ES 11.7 ± 4.1%) increases in power output (PO), respectively. The overall PC effect became unclear after HA (+4 ± 14 W; ES 1.4 ± 3.0%). However, pacing analysis revealed that PC remained transiently beneficial post-HA, i.e., during the first half of the TT. Both HA and PC pre-HA were characterized by an enhanced PO without increased cardio-thermoregulatory or perceptual disturbances, while post-HA PC only improved thermal comfort. PC improved 20-km TT performance in unacclimatized athletes, but an 8-day HA period attenuated the magnitude of this effect. The respective converging physiological responses to HA and PC may explain the blunting of PC effectiveness. However, perceptual benefits from PC can still account for the small alterations to pacing noted post-HA.
Kastelein, T.E., Duffield, R., Crowcroft, S. & Marino, F.E. 2017, 'Cerebral oxygenation and sympathetic responses to smoking in young and middle-aged smokers.', Human and Experimental Toxicology, vol. 36, no. 2, pp. 184-194.
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This study examined the effects of acute tobacco smoking on cerebral oxygenation and autonomic function in 28 male, habitual smokers of shorter young smokers (YSM) or longer middle-aged smokers (MSM) smoking history. Following baseline testing, participants undertook a smoking protocol involving the consumption of two cigarettes within 15 min. Measures of cerebral oxygenation and autonomic function were collected before, during, and 0 min, 30 min, 1 h, and 4 h post-smoking. Tissue saturation index (TSI) for MSM was greater than YSM during cigarette consumption (p< 0.05). Moreover, MSM observed significant within-group changes for TSI during and post-cigarette consumption (p< 0.05). Further, MSM observed an increase in low frequency (LF) band from 30 min to 1 h post-consumption, followed by a decline, whereas elevations above MSM were observed in YSM at 4 h (p< 0.05). Both MSM and YSM showed a decrease in high-frequency (HF) band post-cigarette, while increased LF/HF ratio post-consumption was observed in YSM. A decline in the standard deviation of RR intervals, post-cigarette consumption was evident in MSM (p< 0.05). Moreover, the root mean square of RR interval in both groups similarly decreased following cigarette consumption (p< 0.05). Acute smoking affects heart rate variability, suggestive of vagal withdrawal, and maybe indicate an effect of smoking history. Additionally, prolonged smoking history alters cerebral microcirculatory responses to acute tobacco exposure in MSM.
Vickery, W., Duffield, R., Crowther, R., Beakley, D., Blanch, P. & Dascombe, B.J. 2017, 'Comparison of the physical and technical demands of cricket players during training and match-play.', Journal of Strength and Conditioning Research.
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This study aimed to determine which training method (net-based sessions or centre-wicket simulations) currently used in national level and U19 male players cricket provided a more physical and technical match-specific training response. The heart rate, rating of perceived exertion and movement patterns of 42 male, cricket players were measured across the various training and match formats. Video analysis was coded retrospectively to quantify technical loads based on the cricket skills performed. Magnitude based inferences were based on the standardization of effect and presented with &plusmn;90% confidence intervals. Regardless of playing position, differences in physiological demands between training modes and match-play were unclear, with the exception of higher heart rates in fielders during traditional net sessions (mean heart rate: d= -2.7 [-4.7; -0.7]; 75% of maximum heart rate: d= -1.7 [-3.2; -0.2]). Typically, the movement demands of centre-wicket simulations were similar or greater than match-play, which was most evident in the distance travelled at a high-intensity within each playing position (batsmen: d= 6.4 [3.7; 9.2]; medium-fast bowlers: d= 1.71 [0.1; 3.3]; spin bowlers: d= 6.5 [0.01; 13.0]; fielders: d= 0.8 [-0.2; 1.7]), respectively. The technical demands of traditional net cricket training exceeded that of a typical match for each playing position. Specifically, fast bowlers delivered a greater number of balls during net-bowling compared to a match (d= -2.2 [-3.6; 0.9]). In conclusion, centre-wicket simulations more closely matched the physical demands of a One-Day match within batsmen and spin bowlers, whereas traditional cricket training often exceeded match-specific demands.
Duffield, R., Vickery, W. & Dascombe, B. 2017, 'The Association Between Internal and External Measures of Training Load in Batsmen and Medium-Fast Bowlers During Net-Based Cricket Training', International Journal of Sports Physiology and Performance, vol. 12, no. 2, pp. 247-253.
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Purpose: To examine the relationship between session rating of perceived exertion (sRPE) and measures of internal and external training load (TL) in cricket batsmen and medium-fast bowlers during net-based training sessions. Methods: The internal (heart rate), external (movement demands, PlayerLoad), and technical (cricket-specific skills) loads of 30 male cricket players (age 21.2 &plusmn; 3.8 y, height 1.82 &plusmn; 0.07 m, body mass 79.0 &plusmn; 8.7 kg) were determined from net-based cricket-training sessions (n = 118). The relationships between sRPE and measures of TL were quantified using Pearson product&#8211;moment correlations respective to playing position. Stepwise multiple-regression techniques provided key internal- and external-load determinants of sRPE in cricket players. Results: Significant correlations were evident (r = -.34 to .87, P < .05) between internal and external measures of TL and sRPE, with the strongest correlations (r .62) for GPS-derived measures for both playing positions. In batsmen, stepwise multiple-regression analysis revealed that 67.8% of the adjusted variance in sRPE could be explained by PlayerLoad and high-intensity distance (y = 27.43 + 0.81 PlayerLoad + 0.29 high-intensity distance). For medium-fast bowlers, 76.3% of the adjusted variance could be explained by total distance and mean heart rate (y = 101.82 + total distance 0.05 + HRmean &#8211; 0.48). Conclusion: These results suggest that sRPE is a valid method of reporting TL among cricket batsmen and medium-fast bowlers. Position-specific responses are evident and should be considered when monitoring the TL of cricket players.
McCleave, E.L., Slattery, K.M., Duffield, R., Saunders, P.U., Sharma, A.P., Crowcroft, S.J. & Coutts, A.J. 2017, 'Temperate Performance Benefits after Heat, but Not Combined Heat and Hypoxic Training.', Medicine and Science in Sports and Exercise, vol. 49, no. 3, pp. 509-517.
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PURPOSE: Independent heat and hypoxic exposure can enhance temperate endurance performance in trained athletes, although their combined effects remain unknown. This study examined whether the addition of heat interval training during "live high, train low" (LHTL) hypoxic exposure would result in enhanced performance and physiological adaptations as compared with heat or temperate training. METHODS: Twenty-six well-trained runners completed 3 wk of interval training assigned to one of three conditions: 1) LHTL hypoxic exposure plus heat training (H + H; 3000 m for 13 hd, train at 33&deg;C, 60% relative humidity [RH]), 2) heat training with no hypoxic exposure (HOT, live at <600 m and train at 33&deg;C, 60% RH), or 3) temperate training with no hypoxic exposure (CONT; live at <600 m and train at 14&deg;C, 55% RH). Performance 3-km time-trials (3-km TT), running economy, hemoglobin mass, and plasma volume were assessed using magnitude-based inferences statistical approach before (Baseline), after (Post), and 3 wk (3wkP) after exposure. RESULTS: Compared with Baseline, 3-km TT performance was likely increased in HOT at 3wkP (-3.3% &plusmn; 1.3%; mean &plusmn; 90% confidence interval), with no performance improvement in either H + H or CONT. Hemoglobin mass increased by 3.8% &plusmn; 1.8% at Post in H + H only. Plasma volume in HOT was possibly elevated above H + H and CONT at Post but not at 3wkP. Correlations between changes in 3-km TT performance and physiological adaptations were unclear. CONCLUSION: Incorporating heat-based training into a 3-wk training block can improve temperate performance at 3 wk after exposure, with athlete psychology, physiology, and environmental dose all important considerations. Despite hematological adaptations, the addition of LHTL to heat interval training has no greater 3-km TT performance benefit than temperate training alone.
Gescheit, D.T., Duffield, R., Skein, M., Brydon, N., Cormack, S.J. & Reid, M. 2017, 'Effects of consecutive days of match play on technical performance in tennis.', Journal of Sports Sciences, vol. 35, no. 20, pp. 1988-1994.
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Elite tennis is characterised by repeated bouts of up to 5-set match play, yet little is known about the technical requirements of shots played. This study therefore investigated technical performance changes over consecutive days of prolonged, simulated tennis match play. A total of 7 well-trained men tennis players performed 4 consecutive days of competitive 4-h match play. Matches were notated to determine between-day changes in groundstroke and serve performance, as well as point and match durations. Changes 75% likely to exceed the smallest important effect size (0.2) were considered meaningful and represented as effect size&nbsp;&plusmn;&nbsp;90% confidence interval. Effective playing time reduced on days 3 and 4, alongside likely increases in "stretch" groundstrokes over the 4&nbsp;days (mean effect size &plusmn; 90% confidence interval; 0.57&nbsp;&plusmn;&nbsp;0.38) and "stretch" backhand returns on days 2 and 3 (0.39&nbsp;&plusmn;&nbsp;0.54 and 0.67&nbsp;&plusmn;&nbsp;0.55). Relative unforced errors increased on day 4 (vs. day 2; 0.36&nbsp;&plusmn;&nbsp;0.22) and second-serve winning percentage reduced after day 1 (-0.47&nbsp;&plusmn;&nbsp;0.50). Further, a likely increase in emotional outbursts characterised day 3 (vs. day 2; 0.73&nbsp;&plusmn;&nbsp;0.57). Consecutive-day match play impairs hitting accuracy, stroke positioning and emotional responses; an understanding of which prepares players for elite-standard tennis tournament play.
Kastelein, T.E., Donges, C.E., Mendham, A.E. & Duffield, R. 2017, 'The Acute Exercise-Induced Inflammatory Response: A Comparison of Young-Adult Smokers and Nonsmokers.', Research Quarterly for Exercise and Sport, vol. 88, no. 1, pp. 15-25.
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PURPOSE: This study examined postexercise inflammatory and leukocyte responses in smokers and nonsmokers, as well as the effects of cigarette smoking on the acute postexercise inflammatory and leukocyte response in habitual smokers. METHOD: Eleven recreationally active male smokers and 11 nonsmokers matched for age and aerobic fitness were familiarized and underwent baseline fitness testing. Participants then completed 40&nbsp;min of cycling at 50% peak aerobic workload. Smokers performed 2 randomized exercise sessions, including an acute postexercise smoking condition (2 cigarettes in 15&nbsp;min of 12&nbsp;mg tar and 1&nbsp;mg nicotine) and a no-smoking condition, while nonsmokers performed 1 exercise session without smoking. Venous blood was obtained preexercise and postexercise for analysis of interleukin (IL)-6, IL-1 receptor antagonist (ra), tumor necrosis factor-alpha (TNF-), and c-reactive protein (CRP). RESULTS: No differences existed between groups for resting CRP (d&nbsp;=&nbsp;0.25-0.46; p&nbsp;=&nbsp;.374-.617). Despite no baseline difference (d&nbsp;=&nbsp;0.03-0.07; p&nbsp;=&nbsp;.141-.70), exercise-induced increases were observed for IL-1 ra in smokers (d&nbsp;=&nbsp;0.50; p&nbsp;=&nbsp;.024-.033), which was not observed in the never-smoker group. No between-group difference was observed for IL-6 across all points (d&nbsp;=&nbsp;0.09-0.5; p&nbsp;=&nbsp;.102-.728); however, all groups observed significant within-group change (d&nbsp;=&nbsp;0.27-1.09; p&nbsp;=&nbsp;.001-.042). Further, TNF- for smokers smoking was elevated above both smokers not smoking and nonsmokers at baseline and across the protocol (d&nbsp;=&nbsp;1.20-1.80; d&nbsp;=&nbsp;0.20-1.0; p&nbsp;=&nbsp;.001-.035). Additionally, a marked postexercise increase in leukocyte and neutrophil concentrations was evident in smokers smoking compared with nonsmokers and smokers not smoking as indicated by a moderate-to-large effect size (d&nbsp;=&nbsp;0.72; d&nbsp;=&nbsp;0.78). CONCLUSION: Consequently, male smokers exhibit an altered postexercise proinflammatory profile compared with age- and fitness-matched nonsmokers.
Schmit, C., Hausswirth, C., Le Meur, Y. & Duffield, R. 2017, 'Cognitive Functioning and Heat Strain: Performance Responses and Protective Strategies.', Sports Medicine, vol. 47, no. 7, pp. 1289-1302.
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Despite the predominance of research on physical performance in the heat, many activities require high cognitive functioning for optimal performance (i.e. decision making) and/or health purposes (i.e. injury risk). Prolonged periods of demanding cognitive activity or exercise-induced fatigue will incur altered cognitive functioning. The addition of hot environmental conditions will exacerbate poor cognitive functioning and negatively affect performance outcomes. The present paper attempts to extract consistent themes from the heat-cognition literature to explore cognitive performance as a function of the level of heat stress encountered. More specifically, experimental studies investigating cognitive performance in conditions of hyperthermia, often via the completion of computerised tasks (i.e. cognitive tests), are used to better understand the relationship between endogenous thermal load and cognitive performance. The existence of an inverted U-shaped relationship between hyperthermia development and cognitive performance is suggested, and highlights core temperatures of ~38.5&nbsp;&deg;C as the potential 'threshold' for hyperthermia-induced negative cognitive performance. From this perspective, interventions to slow or blunt thermal loads and protect both task- and hyperthermia-related changes in task performances (e.g. cooling strategies) could be used to great benefit and potentially preserve cognitive performance during heat strain.
Fowler, P.M., McCall, A., Jones, M. & Duffield, R. 2017, 'Effects of long-haul transmeridian travel on player preparedness: Case study of a national team at the 2014 FIFA World Cup.', Journal of Science and Medicine in Sport, vol. 20, no. 4, pp. 322-327.
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OBJECTIVES: Describe the effects of eastward long-haul transmeridian air travel on subjective jet-lag, sleep and wellness in professional football (soccer) players prior to the 2014 FIFA World Cup in Brazil. DESIGN: Single cohort involving twenty-two male professional football players representing a national football team. METHODS: Data was collected from players prior to and following international travel from Sydney, Australia to Vitoria, Brazil. In total there were three flights, 19-h and 14,695km of travel east across 11 time-zones. Training load and wellness measures were obtained in the week prior to and following travel, whilst sleep and jet-lag measures were collected on the day prior to travel (Pre), the day of arrival and for five days following travel (Post 1-5). RESULTS: Compared to Pre, perceived jet-lag was significantly increased on Post 1 to 4, with significantly greater levels on Post 1 compared to Post 5 (p<0.05). Self-reported sleep duration during travel was 5.9 (4.8-7.0) h, which was significantly lower than all other nights (p0.01), except for the night of arrival, where time in bed and sleep duration were significantly reduced compared to Post 1-4 (p0.01). Lastly, compared to the week prior to travel, mean wellness was significantly reduced during the week following travel (p0.01). CONCLUSIONS: Self-reported sleep disruption during and following eastward long-haul transmeridian air travel, together with exacerbated jet-lag symptoms may result in reduced player wellness. Consequently, player preparedness for subsequent training and competition may be impeded, though physical performance data is lacking.
Allen, N.G., Higham, S.M., Mendham, A.E., Kastelein, T.E., Larsen, P.S. & Duffield, R. 2017, 'The effect of high-intensity aerobic interval training on markers of systemic inflammation in sedentary populations.', Eur J Appl Physiol, vol. 117, no. 6, pp. 1249-1256.
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PURPOSE: This study examined the effects of high-intensity interval training (HIIT; 30&nbsp;s sprint, 4-5&nbsp;min passive recovery) and prolonged intermittent sprint training (PIST; 10&nbsp;s sprint, 2-3&nbsp;min moderate exercise) on the systemic inflammatory markers C-reactive protein (CRP) and tumor necrosis factor- (TNF-), aerobic capacity, and anthropometry in a middle-aged, sedentary population. METHODS: Fifty-five sedentary adults (age 49.2&nbsp;&plusmn;&nbsp;6.1&nbsp;years) were randomised into HIIT (n&nbsp;=&nbsp;20), PIST (n&nbsp;=&nbsp;21), or a sedentary control group (CTRL n&nbsp;=&nbsp;14). HIIT and PIST performed three training sessions per week for 9&nbsp;weeks on a cycle ergometer, matched for total high-intensity time, while CTRL continued normal sedentary behaviours. Pre- and post-intervention testing involved measures of anthropometry, peak oxygen consumption (VO2peak), and venous blood collection for analyses of CRP and TNF-. RESULTS: HIIT and PIST increased VO2peak compared to CTRL (+3.66&nbsp;&plusmn;&nbsp;2.23 and 3.74&nbsp;&plusmn;&nbsp;2.62&nbsp;mL&nbsp;kg&nbsp;min(-1)). A group&nbsp;&nbsp;time interaction (p&nbsp;=&nbsp;0.042) and main effect of time (p&nbsp;=&nbsp;0.026) were evident for waist girth, with only HIIT showing a significant reduction compared to CTRL (-2.1&nbsp;&plusmn;&nbsp;2.8&nbsp;cm). TNF- and CRP showed no group&nbsp;&nbsp;time interaction or time effect (p&nbsp;>&nbsp;0.05). CONCLUSIONS: In sedentary individuals, 9&nbsp;weeks of HIIT or PIST were effective to improve aerobic capacity; however, only HIIT significantly reduced waist girth and WHR compared to CTRL. Markers of systemic inflammation remained unchanged across all groups. Accordingly, for inflammation and VO2peak, the distribution of sprints and the active or passive recovery periods are inconsequential provided that total duration of high-intensity efforts is similar.
Kastelein, T., Duffield, R. & Marino, F. 2017, 'Human in situ cytokine and leukocyte responses to acute smoking.', Journal of Immunotoxicology, vol. 14, no. 1, pp. 109-115.
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This study examined immune/inflammatory parameters following an acute tobacco smoking episode in smokers with varying smoking histories. Twenty-eight male habitual smokers were categorized according to smoking history, e.g. younger smoker (YSM) or middle-aged smoker (MSM). Participants were matched for fitness and smoking habits and following baseline testing, undertook a smoking protocol involving consumption of two cigarettes within 15min. Venous blood was collected pre- and immediately, 1h, and 4h post-protocol to permit analyses of circulating levels of interleukin (IL)-6, IL-1, IL-1ra, monocyte chemoattractant protein-1 (MCP-1), C-reactive protein (CRP), and leukocytes. No baseline differences were observed between groups for IL-1ra, IL-1, or leukocytes. MCP-1 and IL-6 levels were significantly (p<0.05) elevated at baseline in YSM. Both groups showed an increase in MCP-1 levels from pre- to immediately post-cigarette consumption. The MSM also displayed an increase in IL-6 post-smoking, followed by a decline over the period from 1 to 4h thereafter. A significant decline in circulating lymphocyte and eosinophil levels from immediately post-cigarette consumption to 1h later was observed in both groups. Monocyte levels in the YSM followed a similar profile but no significant effects on this cell type were evident in the MSM. From these results, a 10-year difference in smoking history induces mild leukopenia. Altered responses due to smoking were also evident with respect to levels of circulating biomarkers, which may be indicative of an effect of differences in cumulative smoking history.
Gescheit, D.T., Cormack, S.J., Duffield, R., Kovalchik, S., Wood, T.O., Omizzolo, M. & Reid, M. 2017, 'Injury epidemiology of tennis players at the 2011-2016 Australian Open Grand Slam.', British Journal of Sports Medicine.
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AIM: To examine the epidemiology and in-event treatment frequency of injury at the 2011-2016 Australian Open tournaments. METHODS: Injury incidence was defined as a medical consultation by a tournament physician and in-event treatment frequency as the mean total number of follow-up medical/physiotherapy consultations (2013-2016 tournaments only). Data were collated by sex, injury region and type and reported as frequencies per 10000 game exposures. Incidence rate s&plusmn; 95%CI and rate ratios were used to test effects for injury, sex and year. RESULTS: Female players experienced more injuries than male players (201.7 vs 148.6). The shoulder (5.1&plusmn;1.1 injuries per year), foot (3.2&plusmn;1.1), wrist (3.1&plusmn;1.5) and knee (3.1&plusmn;1.1) were the most commonly injured regions among females. Knee (3.5&plusmn;1.6), ankle (2.3&plusmn;1.3) and thigh (2.3&plusmn;1.5) were the most prevalent male injuries. Upper arm injuries and in-event treatment frequency increased by 2.4 times in both sexes over the 5-year period. Muscle injuries were most frequent. There was a greater than twofold increase in men and women with stress fractures over the 5-year period. The torso region, including the neck, thoracic spine, trunk and abdominal, lumbar spine, hip and groin, pelvis/buttock, attracted high in-event treatment frequencies in both sexes. CONCLUSION: Investigation of injury at the Australian Open suggests that females are more commonly injured than males. Upper and lower extremity injuries affected females while lower limb injuries were more prominent in males. There was an increasing rate of in-event treatments of upper limb and torso injuries as well as stress fractures during the observation period.
Larsen, P.S., Donges, C.E., Guelfi, K.J., Smith, G.C., Adams, D.R. & Duffield, R. 2017, 'Effects of Aerobic, Strength or Combined Exercise on Perceived Appetite and Appetite-Related Hormones in Inactive Middle-Aged Men.', International Journal of Sport Nutrition and Exercise Metabolism, pp. 1-23.
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Aerobic exercise (AE) and strength exercise (SE) are reported to induce discrete and specific appetite-related responses; however, the effect of combining AE and SE (i.e. combined exercise; CE) remains relatively unknown. Twelve inactive overweight men (age: 48 &plusmn; 5 y; BMI: 29.9 &plusmn; 1.9 kgm(2)) completed four conditions in a random order: 1) non-exercise control (CON) (50 min seated rest); 2) AE (50 min cycling; 75% VO2peak); 3) SE (10 8 leg extensions; 75% 1RM); and 4) CE (50% SE + 50% AE). Perceived appetite, and appetite-related peptides and metabolites were assessed prior to and up to 2 h post-condition (0P, 30P, 60P, 90P, 120P). Perceived appetite did not differ between trials (p < 0.05). Acylated ghrelin was lower at 0P in AE compared to CON (p = 0.039), while pancreatic polypeptide (PP) was elevated following AE compared to CON and CE. Glucose-dependent insulinotropic peptide (GIPtotal) was greater following all exercise conditions compared to CON, as was glucagon, although concentrations were generally highest in AE (p < 0.05). Glucose was acutely increased with SE and AE (p < 0.05), while insulin and C-peptide were higher after SE compared to all other conditions (p < 0.05). In inactive, middle-aged men AE, SE and CE each have their own distinct effects on circulating appetite-related peptides and metabolites. Despite these differential exercise-induced hormone responses, exercise mode appears to have little effect on perceived appetite compared with a resting control in this population.
Fowler, P.M., Knez, W., Crowcroft, S., Mendham, A.E., Miller, J., Sargent, C., Halson, S. & Duffield, R. 2017, 'Greater effect of east vs. west travel on jet-lag, sleep and team-sport performance.', Medicine and Science in Sports and Exercise.
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PURPOSE: Determine the recovery timeline of sleep, subjective jet-lag and fatigue, and team-sport physical performance following east and west long-haul travel. METHODS: Ten, physically-trained males underwent testing at 09:00 (AM) and 17:00 (PM) local time on four consecutive days two weeks prior to outbound travel (BASE), and the first four days following 21 h of outbound (WEST) and return (EAST) air travel across eight time-zones between Australia and Qatar. Data collection included performance (countermovement jump [CMJ], 20-m sprint and Yo-Yo Intermittent Recovery level 1 [YYIR1] test) and perceptual (jet-lag, motivation, perceived exertion and physical feeling) measures. In addition, sleep was measured via wrist activity monitors and self-report diaries throughout the aforementioned data collection periods. RESULTS: Compared to the corresponding day at BASE, the reduction in YYIR1 distance following EAST was significantly different to the increase WEST on day 1 post-travel (p<0.001). On day 2, significantly slower 20-m sprint times were detected in EAST compared to WEST (p=0.03), with large effect sizes also indicating a greater reduction in YYIR1 distance in EAST compared to WEST (d=1.06). Mean sleep onset and offset were significantly later and mean time in bed and sleep duration were significantly reduced across the four days in EAST compared to BASE and WEST (p<0.05). Lastly, mean jet-lag, fatigue and motivation ratings across the four days were significantly worse in EAST compared to BASE and WEST (p<0.05), and WEST compared to BASE (p<0.05). CONCLUSIONS: Long-haul transmeridian travel can impede team-sport physical performance. Specifically, travel east has a greater detrimental effect on sleep, subjective jet-lag, fatigue and motivation. Consequently, maximal- and intermittent-sprint performance is also reduced following travel east, particularly within 72 h following arrival.
Murphy, A.P., Duffield, R., Kellett, A. & Reid, M. 2016, 'A Comparison of the Perceptual and Technical Demands of Tennis Training, Simulated Match Play, and Competitive Tournaments.', International journal of sports physiology and performance, vol. 11, no. 1, pp. 40-47.
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High-performance tennis environments aim to prepare athletes for competitive demands through simulated-match scenarios and drills. With a dearth of direct comparisons between training and tournament demands, the current investigation compared the perceptual and technical characteristics of training drills, simulated match play, and tournament matches.Data were collected from 18 high-performance junior tennis players (gender: 10 male, 8 female; age 16 &plusmn; 1.1 y) during 6 &plusmn; 2 drill-based training sessions, 5 &plusmn; 2 simulated match-play sessions, and 5 &plusmn; 3 tournament matches from each participant. Tournament matches were further distinguished by win or loss and against seeded or nonseeded opponents. Notational analysis of stroke and error rates, winners, and serves, along with rating of perceived physical exertion (RPE) and mental exertion was measured postsession.Repeated-measures analyses of variance and effect-size analysis revealed that training sessions were significantly shorter in duration than tournament matches (P < .05, d = 1.18). RPEs during training and simulated match-play sessions were lower than in tournaments (P > .05; d = 1.26, d = 1.05, respectively). Mental exertion in training was lower than in both simulated match play and tournaments (P > .05; d = 1.10, d = 0.86, respectively). Stroke rates during tournaments exceeded those observed in training (P < .05, d = 3.41) and simulated-match-play (P < .05, d = 1.22) sessions. Furthermore, the serve was used more during tournaments than simulated match play (P < .05, d = 4.28), while errors and winners were similar independent of setting (P > .05, d < 0.80).Training in the form of drills or simulated match play appeared to inadequately replicate tournament demands in this cohort of players. Coaches should be mindful of match demands to best prescribe sessions of relevant duration, as well as internal (RPE) and technical (stroke rate) load, to aid tournament preparation.
Fullagar, H.H., Duffield, R., Skorski, S., White, D., Bloomfield, J., Kölling, S. & Meyer, T. 2016, 'Sleep, Travel, and Recovery Responses of National Footballers During and After Long-Haul International Air Travel.', International journal of sports physiology and performance, vol. 11, no. 1, pp. 86-95.
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The current study examined the sleep, travel, and recovery responses of elite footballers during and after long-haul international air travel, with a further description of these responses over the ensuing competitive tour (including 2 matches).In an observational design, 15 elite male football players undertook 18 h of predominantly westward international air travel from the United Kingdom to South America (-4-h time-zone shift) for a 10-d tour. Objective sleep parameters, external and internal training loads, subjective player match performance, technical match data, and perceptual jet-lag and recovery measures were collected.Significant differences were evident between outbound travel and recovery night 1 (night of arrival; P < .001) for sleep duration. Sleep efficiency was also significantly reduced during outbound travel compared with recovery nights 1 (P = .001) and 2 (P = .004). Furthermore, both match nights (5 and 10), showed significantly less sleep than nonmatch nights 2 to 4 and 7 to 9 (all P < .001). No significant differences were evident between baseline and any time point for all perceptual measures of jet-lag and recovery (P > .05), although large effects were evident for jet-lag on d 2 (2 d after arrival).Sleep duration is truncated during long-haul international travel with a 4-h time-zone delay and after night matches in elite footballers. However, this lost sleep appeared to have a limited effect on perceptual recovery, which may be explained by a westbound flight and a relatively small change in time zones, in addition to the significant increase in sleep duration on the night of arrival after the long-haul flight.
Schmit, C., Duffield, R., Hausswirth, C., Coutts, A.J. & Le Meur, Y. 2016, 'Pacing Adjustments Associated With Familiarisation: Heat vs. Temperate Environments.', International journal of sports physiology and performance.
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This study describes the effect of the initial perceptual experience from heat-familiarisation on the pacing profile during free-paced endurance time-trial (TT) compared to temperate conditions.Two groups of well-trained triathletes performed two 20-km TT's either in hot (35&deg;C and 50% RH, N = 12) or temperate (21&deg;C and 50% RH, N = 22) conditions, after standardisation of training for each group prior to both trials. To ensure no physiological acclimation differences between conditions, the TT's for both groups were separated by 11 &plusmn; 4 days.Performance improvement in the heat (11 &plusmn; 24 W) from the first to second trial appeared comparable to that in temperate conditions (8 &plusmn; 14 W, p = 0.67). However, the specific alteration in pacing profile in the heat was markedly different to temperate, with a change from 'positive' to an 'even' pacing strategy.Altered perceptions of heat during heat-familiarization, rather than physiological acclimatization per se, may mediate initial changes in pacing and TT performance in the heat. These results highlight the need for athletes without time for sufficient HA to familiarise themselves with hot conditions to reduce the uncertainty from behaviour-based outcomes that may impede performance.
Fullagar, H.H., Skorski, S., Duffield, R., Julian, R., Bartlett, J. & Meyer, T. 2016, 'Impaired sleep and recovery after night matches in elite football players.', Journal of Sports Sciences, vol. 34, no. 14, pp. 1333-1339.
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Despite the perceived importance of sleep for elite footballers, descriptions of the duration and quality of sleep, especially following match play, are limited. Moreover, recovery responses following sleep loss remain unclear. Accordingly, the present study examined the subjective sleep and recovery responses of elite footballers across training days (TD) and both day and night matches (DM and NM). Sixteen top division European players from three clubs completed a subjective online questionnaire twice a day for 21&nbsp;days during the season. Subjective recall of sleep variables (duration, onset latency, time of wake/sleep, wake episode duration), a range of perceptual variables related to recovery, mood, performance and internal training loads and non-exercise stressors were collected. Players reported significantly reduced sleep durations for NM compared to DM (-157&nbsp;min) and TD (-181&nbsp;min). In addition, sleep restfulness (SR; arbitrary scale 1&nbsp;=&nbsp;very restful, 5&nbsp;=&nbsp;not at all restful) and perceived recovery (PR; acute recovery and stress scale 0&nbsp;=&nbsp;not recovered at all, 6&nbsp;=&nbsp;fully recovered) were significantly poorer following NM than both TD (SR: +2.0, PR: -2.6), and DM (SR: +1.5; PR: -1.5). These results suggest that reduced sleep quantity and quality and reduced PR are mainly evident following NM in elite players.
Chan, V., Duffield, R. & Watsford, M. 2016, 'The effects of compression garments on performance of prolonged manual-labour exercise and recovery.', Applied Physiology, Nutrition and Metabolism, vol. 41, no. 2, pp. 125-132.
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This study investigated the effects of wearing compression garments during and 24 h following a 4-h exercise protocol simulating manual-labour tasks. Ten physically trained male participants, familiar with labouring activities, undertook 4 h of work tasks characteristic of industrial workplaces. Participants completed 2 testing sessions, separated by at least 1 week. In the experimental condition, participants wore a full-length compression top and compression shorts during the exercise protocol and overnight recovery, with normal work clothes worn in the control condition. Testing for serum creatine kinase and C-reactive protein, handgrip strength, knee flexion and extension torque, muscle stiffness, perceived muscle soreness and fatigue as well as heart rate and rating of perceived exertion (RPE) responses to 4-min cycling were performed before, following, and 24 h after exercise. Creatine kinase, muscle soreness, and rating of perceived fatigue increased following the exercise protocol (p < 0.05) as did RPE to a standardised cycling warm-up bout. Conversely, no postexercise changes were observed in C-reactive protein, handgrip strength, peak knee flexion torque, or stiffness measures (p > 0.05). Knee extension torque was significantly higher in the control condition at 24 h postexercise (3.1% &plusmn; 5.4% change; compression: 2.2% &plusmn; 11.1% change), although no other variables were different between conditions at any time. However, compression demonstrated a moderate-large effect (d > 0.60) to reduce perceived muscle soreness, fatigue, and RPE from standardised warm-up at 24 h postexercise. The current findings suggest that compression may assist in perceptual recovery from manual-labour exercise with implications for the ability to perform subsequent work bouts.
Fowler, P.M., Duffield, R., Lu, D., Hickmans, J.A. & Scott, T.J. 2016, 'Subjective jet-lag and sleep responses and URTI symptoms following long-haul transmeridian travel in professional rugby league players.', International Journal of Sports Physiology and Performance.
Duffield, R., Allen, N.G. & Mendham, A.E. 2016, 'The health benefits of rugby-specific small-sided games for sedentary populations', World Congress of Science and Football.
Mendham, A., Duffield, R., Coutts, A.J., Marino, F.E., Boyko, A. & Bishop, D.J. 2016, 'Small-sided games training improves risk factors associated with preventing diabetes', PLoS One.
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Fullagar, H., Skorski, S., Duffield, R. & Meyer, T. 2016, 'The effect of an acute sleep hygiene strategy following a late-night soccer match on recovery of players.', Chronobiology international, vol. 33, no. 5, pp. 490-505.
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Elite soccer players are at risk of reduced recovery following periods of sleep disruption, particularly following late-night matches. It remains unknown whether improving sleep quality or quantity in such scenarios can improve post-match recovery. Therefore, the aim of this study was to investigate the effect of an acute sleep hygiene strategy (SHS) on physical and perceptual recovery of players following a late-night soccer match. In a randomised cross-over design, two highly-trained amateur teams (20 players) played two late-night (20:45) friendly matches against each other seven days apart. Players completed an SHS after the match or proceeded with their normal post-game routine (NSHS). Over the ensuing 48 h, objective sleep parameters (sleep duration, onset latency, efficiency, wake episodes), countermovement jump (CMJ; height, force production), YoYo Intermittent Recovery test (YYIR2; distance, maximum heart rate, lactate), venous blood (creatine kinase, urea and c-reactive protein) and perceived recovery and stress markers were collected. Sleep duration was significantly greater in SHS compared to NSHS on match night (P = 0.002, d = 1.50), with NSHS significantly less than baseline (P < 0.001, d = 1.95). Significant greater wake episodes occurred on match night for SHS (P = 0.04, d = 1.01), without significant differences between- or within-conditions for sleep onset latency (P = 0.12), efficiency (P = 0.39) or wake episode duration (P = 0.07). No significant differences were observed between conditions for any physical performance or venous blood marker (all P > 0.05); although maximum heart rate during the YYIR2 was significantly higher in NSHS than SHS at 36 h post-match (P = 0.01; d = 0.81). There were no significant differences between conditions for perceptual "overall recovery" (P = 0.47) or "overall stress" (P = 0.17). Overall, an acute SHS improved sleep quantity following a late-night soccer match; albeit without any improvement in physical perfo...
Fowler, P.M., Duffield, R., Lu, D., Hickmans, J.A. & Scott, T.J. 2016, 'Effects of Long-Haul Transmeridian Travel on Subjective Jet-Lag and Self-Reported Sleep and Upper Respiratory Symptoms in Professional Rugby League Players.', International Journal of Sports Physiology and Performance, vol. 11, no. 7, pp. 876-884.
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The present study examined the effects of 24 h travel west across 11 time-zones on subjective jet-lag and wellness responses, together with self-reported sleep and upper respiratory symptoms in eighteen professional rugby league players. Measures were obtained one or two days prior to (Pre), and two, six and eight days following travel (Post 2, 6 and 8) from Australia to the United Kingdom for the 2015 World Club Series. Compared to Pre, subjective jet-lag remained significantly elevated on Post 8 (3.1 &plusmn; 2.3); p<0.05, d>0.90), though was greatest on Post 2 (4.1 &plusmn; 1.4). Self-reported sleep onset times were significantly earlier on Post 2 compared to all other time points (p<0.05, d>0.90) and large effect sizes suggested wake times were earlier on Post 2 compared to Post 6 and 8 (d>0.90). While significantly more upper respiratory symptoms were reported on Post 6 compared to Pre (p<0.05, d>0.90), no incidence of injury and negligible changes in wellness and muscle strength and range of motion (p>0.05, d<0.90) were evident following travel. Results suggest that westward long-haul travel between Australia and the United Kingdom exacerbates subjective jet-lag and sleep responses, along with upper respiratory symptoms in professional rugby league players. Of note, the increase in self-reported upper respiratory symptoms is a reminder that the demands of long-haul travel may be an additional concern to jet-lag for travelling athletes. However, due to the lack of sport-specific performance measures, it is still unclear whether international travel interferes with training to the extent that subsequent competition performance is impaired.
Mendham, A.E., Duffield, R., Coutts, A.J., Marino, F.E., Boyko, A., McAinch, A.J. & Bishop, D.J. 2016, 'Similar mitochondrial signaling responses to a single bout of continuous or small-sided-games-based exercise in sedentary men.', Journal of Applied Physiology, vol. 121, no. 6, pp. 1326-1334.
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This study assessed the mitochondrial related signaling responses to a single bout of noncontact, modified football (touch rugby), played as small-sided games (SSG), or cycling (CYC) exercise in sedentary, obese, middle-aged men. In a randomized, crossover design, nine middle-aged, sedentary, obese men completed two, 40-min exercise conditions (CYC and SSG) separated by a 21-day recovery period. Heart rate (HR) and ratings of perceived exertion (RPE) were collected during each bout. Needle biopsies from the vastus lateralis muscle were collected at rest and 30 and 240 min postexercise for analysis of protein content and phosphorylation (PGC-1, SIRT1, p53, p53(Ser15), AMPK, AMPK(Thr172), CAMKII, CAMKII(Thr286), p38MAPK, and p38MAPK(Thr180/Tyr182)) and mRNA expression (PGC-1, p53, NRF1, NRF2, Tfam, and cytochrome c). A main effect of time effect for both conditions was evident for HR, RPE, and blood lactate (P < 0.05), with no condition by time interaction (P > 0.05). Both conditions increased PGC1- protein and mRNA expression at 240 min (P < 0.05). AMPK(Thr172) increased 30 min post CYC (P < 0.05), with no change in SSG (P > 0.05). CYC increased p53 protein content at 240 min to a greater extent than SSG (P < 0.05). mRNA expression of NRF2 decreased in both conditions (P < 0.05). No condition by time interactions were evident for mRNA expression of Tfam, NRF1, cytochrome c, and p53. The similar PGC-1 response between intensity-matched conditions suggests both conditions are of similar benefit for stimulating mitochondrial biogenesis. Differences between conditions regarding fluctuation in exercise intensity and type of muscle contraction may explain the increase of p53 and AMPK within CYC and not SSG (noncontact, modified football).
Wanner, S.P., Wilke, C.F. & Duffield, R. 2016, 'Nutritional strategies for maximizing recovery from strenuous exercise in the heat: An important role for carbohydrate (sago) supplementation.', Temperature (Austin), vol. 3, no. 3, pp. 366-368.
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Fullagar, H.H.K., Skorski, S., Duffield, R., Hammes, D., Coutts, A.J. & Meyer, T. 2015, 'Sleep and Athletic Performance: The Effects of Sleep Loss on Exercise Performance, and Physiological and Cognitive Responses to Exercise', SPORTS MEDICINE, vol. 45, no. 2, pp. 161-186.
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Mendham, A.E., Duffield, R., Marino, F. & Coutts, A.J. 2015, 'A 12-week sports-based exercise programme for inactive Indigenous Australian men improved clinical risk factors associated with type 2 diabetes mellitus', JOURNAL OF SCIENCE AND MEDICINE IN SPORT, vol. 18, no. 4, pp. 438-443.
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Fowler, P., Duffield, R., Waterson, A. & Vaile, J. 2015, 'Effects of Regular Away Travel on Training Loads, Recovery, and Injury Rates in Professional Australian Soccer Players', INTERNATIONAL JOURNAL OF SPORTS PHYSIOLOGY AND PERFORMANCE, vol. 10, no. 5, pp. 546-552.
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Fowler, P.M., Duffield, R., Morrow, I., Roach, G. & Vaile, J. 2015, 'Effects of sleep hygiene and artificial bright light interventions on recovery from simulated international air travel', EUROPEAN JOURNAL OF APPLIED PHYSIOLOGY, vol. 115, no. 3, pp. 541-553.
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Koklu, Y., Arslan, Y., Alemdaroglu, U. & Duffield, R. 2015, 'Accuracy and reliability of SPI ProX global positioning system devices for measuring movement demands of team sports', JOURNAL OF SPORTS MEDICINE AND PHYSICAL FITNESS, vol. 55, no. 5, pp. 471-477.
Murphy, A.P., Duffield, R., Kellett, A. & Reid, M. 2015, 'The Relationship of Training Load to Physical-Capacity Changes During International Tours in High-Performance Junior Tennis Players', INTERNATIONAL JOURNAL OF SPORTS PHYSIOLOGY AND PERFORMANCE, vol. 10, no. 2, pp. 253-260.
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Fowler, P., Duffield, R. & Vaile, J. 2015, 'Effects of simulated domestic and international air travel on sleep, performance, and recovery for team sports', SCANDINAVIAN JOURNAL OF MEDICINE & SCIENCE IN SPORTS, vol. 25, no. 3, pp. 441-451.
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Mendham, A.E., Duffield, R., Marino, F. & Coutts, A.J. 2015, 'Differences in the acute inflammatory and glucose regulatory responses between small-sided games and cycling in sedentary, middle-aged men.', Journal of science and medicine in sport / Sports Medicine Australia, vol. 18, no. 6, pp. 714-719.
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OBJECTIVES: This study compared the acute inflammatory and glucose regulatory response within and between rugby specific small-sided games and stationary cycling in sedentary, middle-aged Caucasian men. DESIGN: Nine middle-aged, sedentary men who were free from disease participated in 240 min exercise conditions (stationary cycling and small-sided games) in a randomised, cross-over design. METHODS: Heart rate and Rating of Perceived Exertion were collected during each bout. Venous blood was collected at fasting, 0, 30, 60 and 240min post-exercise for measurement of glucose, insulin, cortisol and inflammatory markers including tumour necrosis factor-, interleukin-1, interleukin-6, interleukin-1 receptor agonist and C-reactive protein. RESULTS: No significant differences existed between conditions for heart rate and Rating of Perceived Exertion (p>0.05). Interleukin-6 was increased immediately post-exercise in both conditions (p<0.05), but greater in small-sided games at 240min post-exercise compared with stationary cycling (p<0.05). Glucose was lower in small-sided games than stationary cycling at 30 and 240min post-exercise (p<0.05). Interleukin-1receptor agonist, insulin and cortisol showed an exercise-induced increase (p<0.05), with no significant differences between conditions (p>0.05). Results for C-reactive protein, tumour necrosis factor- and interleukin-1 showed no significant exercise-induced changes within or between conditions (p>0.05). CONCLUSIONS: Both small-sided games and stationary cycling conditions were sufficient to stimulate an acute anti-inflammatory response as indicated by the post-exercise elevation of interleukin-6, interleukin-1receptor agonist and cortisol. The novel findings are that an acute bout of small-sided games bout is capable of maintaining an elevated post-exercise interleukin-6 response and lowered blood glucose concentration, compared with intensity- and duration-matched stationary cycling condition.
Fowler, P., Duffield, R., Howie, K., Waterson, A. & Valle, J. 2015, 'Effects of Northbound Long-Haul International Air Travel on Sleep Quantity and Subjective Jet Lag and Wellness in Professional Australian Soccer Players', INTERNATIONAL JOURNAL OF SPORTS PHYSIOLOGY AND PERFORMANCE, vol. 10, no. 5, pp. 648-654.
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Gescheit, D.T., Cormack, S.J., Reid, M. & Duffield, R. 2015, 'Consecutive Days of Prolonged Tennis Match Play: Performance, Physical, and Perceptual Responses in Trained Players', INTERNATIONAL JOURNAL OF SPORTS PHYSIOLOGY AND PERFORMANCE, vol. 10, no. 7, pp. 913-920.
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Fullagar, H.H.K., Duffield, R., Skorski, S., Coutts, A.J., Julian, R. & Meyer, T. 2015, 'Sleep and Recovery in Team Sport: Current Sleep-Related Issues Facing Professional Team-Sport Athletes', INTERNATIONAL JOURNAL OF SPORTS PHYSIOLOGY AND PERFORMANCE, vol. 10, no. 8, pp. 950-957.
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Murphy, A.P., Duffield, R., Kellett, A., Gescheit, D. & Reid, M. 2015, 'The Effect of Predeparture Training Loads on Posttour Physical Capacities in High-Performance Junior Tennis Players', INTERNATIONAL JOURNAL OF SPORTS PHYSIOLOGY AND PERFORMANCE, vol. 10, no. 8, pp. 986-993.
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McCall, A., Davison, M., Andersen, T.E., Beasley, I., Bizzini, M., Dupont, G., Duffield, R., Carling, C. & Dvorak, J. 2015, 'Injury prevention strategies at the FIFA 2014 World Cup: perceptions and practices of the physicians from the 32 participating national teams', BRITISH JOURNAL OF SPORTS MEDICINE, vol. 49, no. 9, pp. 603-U66.
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Crowcroft, S., Duffield, R., McCleave, E., Slattery, K., Wallace, L.K. & Coutts, A.J. 2015, 'Monitoring training to assess changes in fitness and fatigue: The effects of training in heat and hypoxia', SCANDINAVIAN JOURNAL OF MEDICINE & SCIENCE IN SPORTS, vol. 25, pp. 287-295.
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Mendham, A., Duffield, R., Coutts, A.J., Marino, F.E., Boyko, A. & Bishop, D.J. 2015, 'Rugby-Specific Small-Sided Games Training Is an Effective Alternative to Stationary Cycling at Reducing Clinical Risk Factors Associated with the Development of Type 2 Diabetes: A Randomized, Controlled Trial', PLoS One, vol. 10, no. 6.
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Introduction The present study investigated whether rugby small-sided games (SSG) could be an effective alternative to continuous stationary cycling (CYC) training at reducing clinical risk factors associated with the development of type 2 diabetes mellitus (T2DM). Methods Thirty-three middle-aged (48.6&plusmn;6.6y), inactive men were randomized into a CYC (n=11), SSG (n=11), or control (CON, n=11) group. Participants trained 3d.wk-1 for 8 weeks, while control participants maintained normal activity and dietary patterns. Exercise duration was matched between groups, which involved CYC or SSG (four quarters, interspersed with 2-min passive recovery). Both training programs were designed to induce similar internal loads of maximal heart rate (~80-85%HRmax) and rating of perceived exertion. Pre- and post-intervention testing included dual-energy x-ray absorptiometry scan, graded exercise test, fasting 2h oral glucose tolerance test and resting muscle biopsy. Western blotting was used to assess the content of skeletal muscle proteins associated with mitochondrial biogenesis and glucose regulation. Results Both CYC and SSG increased VO2 at 80%HRmax, and reduced glycated haemoglobin, glucose area under the curve (AUC; SSG, -2.3&plusmn;2.4; CYC -2.2&plusmn;1.6 mmol.L1(120min)1; p<0.05), and total body fat-mass (SSG -2.6&plusmn;0.9%; CYC -2.9&plusmn;1.1%), compared to no change in CON (p<0.05). SSG reduced insulin AUC (-30.4&plusmn;40.7 &micro;lU.mL1(120min)1; p<0.05) and increased total body fat-free mass (1.1&plusmn;1.2kg; p<0.05), with no change in CYC or CON (P>0.05). There were no differences within or between conditions for protein content of peroxisome proliferator-activated receptor gamma coactivator-1, sirtuin-1, p53, glucose transporter-4, protein kinase AKT/PKB, myocyte enhancer factor 2A, mitochondrial transcription factor, nuclear respiratory factor (NRF)-1, NRF-2 or mitochondrial complexes I-V (p>0.05).
Kastelein, T.E., Duffield, R. & Marino, F.E. 2015, 'Acute Immune-Inflammatory Responses to a Single Bout of Aerobic Exercise in Smokers; The Effect of Smoking History and Status.', Frontiers in Immunology, vol. 6, no. 634, pp. 634-634.
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This study examined the acute immune and inflammatory responses to exercise in smokers compared to non-smokers, and further, the effect of smoking history on these immune-inflammatory responses. Fifty-four recreationally active males who were either smokers (SM; n=27) or non-smokers (NS; n=27) were allocated into either young (YSM, YNS) or middle-aged groups (MSM, MNS) based on smoking status. Participants were matched for fitness and smoking habits and following familiarization and baseline testing, undertook an exercise protocol that involved 40min of cycle ergometry at 50% of VO2peak. Venous blood was obtained pre- and post- (0 min, 1, and 4h) exercise to measure circulating leukocytes and inflammatory markers interleukin (IL)-6, IL-1, IL-1ra, and monocyte chemoattractant protein-1 (MCP-1). Compared to MNS, MSM showed elevated basal concentrations of MCP-1, which were increased with a longer smoking history (P<0.05). In response to exercise, YSM demonstrated an amplified IL-6 response from immediately- to 1h-post compared to YNS. Furthermore, IL-1ra in YSM was elevated above that of YNS across all time points (P<0.05). The MSM group had higher IL-1 at baseline when compared to YSM, although IL-1ra was greater for YSM at baseline (P<0.05). Finally, the post-exercise leukocyte response was greater in MSM compared to YSM and non-smokers (P<0.05). In conclusion, smoker's exhibit elevated MCP-1 and IL-1 that seem to be evident with a longer smoking history (~15years). Furthermore, the differences in exercise-induced inflammatory responses noted in YSM may be indicative tobacco smoke exposure priming circulating leukocytes to amplify inflammatory responses.
Gescheit, D.T., Cormack, S.J., Reid, M.R. & Duffield, R. 2015, 'Consecutive days of prolonged tennis matchplay alter movement and physical performance.', International Journal of Sports Physiology and Performance, vol. 10, pp. 913-920.
To determine how consecutive days of prolonged tennis match play affect performance, physiological, and perceptual responses. Methods: Seven well-trained male tennis players completed 4-h tennis matches on 4 consecutive days. Pre- and postmatch measures involved tennis-specific (serve speed and accuracy), physical (20-m sprint, countermovement jump [CMJ], shoulder-rotation maximal voluntary contraction, isometric midthigh pull), perceptual (Training Distress Scale, soreness), and physiological (creatine kinase [CK]) responses. Activity profile was assessed by heart rate, 3D load (accumulated accelerations measured by triaxial accelerometers), and rating of perceived exertion (RPE). Statistical analysis compared within- and between-days values. Changes (&plusmn; 90% confidence interval [CI]) 75% likely to exceed the smallest important effect size (0.2) were considered practically important. Results: 3D load reduced on days 2 to 4 (mean effect size &plusmn; 90% CI &#8211;1.46 &plusmn; 0.40) and effective playing time reduced on days 3 to 4 (&#8211;0.37 &plusmn; 0.51) compared with day 1. RPE did not differ and total points played only declined on day 3 (&#8211;0.38 &plusmn; 1.02). Postmatch 20-m sprint (0.79 &plusmn; 0.77) and prematch CMJ (&#8211;0.43 &plusmn; 0.27) performance declined on days 2 to 4 compared with prematch day 1. Although serve velocity was maintained, compromised postmatch serve accuracy was evident compared with prematch day 1 (0.52 &plusmn; 0.58). CK increased each day, as did ratings of muscle soreness and fatigue. Conclusions: Players reduced external physical loads, through declines in movement, over 4 consecutive days of prolonged competitive tennis. This may be affected by tactical changes and pacing strategies. Alongside this, impairments in sprinting and jumping ability, perceptual and biochemical markers of muscle damage, and reduced mood states may be a function of neuromuscular and perceptual fatigue.
Fowler, P., Duffield, R. & Vaile, J. 2014, 'Effects of domestic air travel on technical and tactical performance and recovery in soccer.', International Journal of Sports Physiology and Performance, vol. 9, pp. 378-386.
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The current study examined the effects of short-haul air travel on competition performance and subsequent recovery. Six male professional Australian football (soccer) players were recruited to participate in the study. Data were collected from 12 matches, which included 6 home and away matches against the same 4 teams. Together with the outcome of each match, data were obtained for team technical and tactical performance indicators and individual player-movement patterns. Furthermore, sleep quantity and quality, hydration, and perceptual fatigue were measured 2 days before, the day of, and 2 days after each match. More competition points were accumulated (P > .05, d = 1.10) and fewer goals were conceded (P > .05, d = 0.93) in home than in away matches. Furthermore, more shots on goal (P > .05, d = 1.17) and corners (P > .05, d = 1.45) and fewer opposition shots on goal (P > .05, d = 1.18) and corners (P < .05, d = 2.32) occurred, alongside reduced total distance covered (P > .05, d = 1.19) and low-intensity activity (P < .05, d = 2.25) during home than during away matches. However, while oxygen saturation was significantly lower during than before and after outbound and return travel (P < .01), equivocal differences in sleep quantity and quality, hydration, and perceptual fatigue were observed before and after competition away compared with home. These results suggest that, compared with short-haul air travel, factors including situational variables, territoriality, tactics, and athlete psychological state are more important in determining match outcome. Furthermore, despite the potential for disrupted recovery patterns, return travel did not impede player recovery or perceived readiness to train.
Vickery, W., Dascombe, B. & Duffield, R. 2014, 'Physiological, movement and technical demands of centre-wicket Battlezone, traditional net-based training and One-Day cricket matches: a comparative study of sub-elite cricket players', Journal of Sports Sciences, vol. 32, no. 8, pp. 722-737.
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This study compared physiological, physical and technical demands of Battlezone, traditional cricket training and one-day matches. Data were initially collected from 11 amateur, male cricket players (age: 22.2 &plusmn; 3.3 year, height: 1.82 &plusmn; 0.06 m body mass: 80.4 &plusmn; 9.8 kg) during four Battlezone and four traditional cricket training sessions encompassing different playing positions. Heart rate, blood lactate concentration, rating of perceived exertion and movement patterns of players were measured. Retrospective video analysis was performed to code for technical outcomes. Similar data were collected from 42 amateur, male cricket players (23.5 &plusmn; 4.7 year, 1.81 &plusmn; 0.07 m, 81.4 &plusmn; 11.4 kg) during one-day matches. Significant differences were found between Battlezone, traditional cricket training and one-day matches within each playing position. Specifically, Battlezone invoked the greatest physiological and physical demands from batsmen in comparison to traditional cricket training and one-day matches. However, the greatest technical demand for batsmen was observed during traditional cricket training. In regards to the other playing positions, a greater physiological, physical and technical demand was observed during Battlezone and traditional training than during one-day matches. These results suggest that the use of Battlezone and traditional cricket training provides players with a suitable training stimulus for replicating the physiological, physical and technical demands of one-day cricket.
Reid, M. & Duffield, R. 2014, 'The development of fatigue during match-play tennis', British Journal of Sports Medicine, vol. 48, pp. 7-11.
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Data describing the activity profile and physiological characteristics of tennis match-play are extensive. However, these data have generally provided descriptive accounts of the one-off match-play of amateur or lowly ranked professional players lasting <3 h. Accordingly, these research efforts have likely failed to fully capture the demands of Grand Slam tennis match-play, particularly in the mens game where matches can last >5 h. Furthermore, there is a distinct lack of evidencebased insight regarding the manifestation of fatigue within and between tennis matches, notwithstanding that skeletal muscle function has been reported to reduce following prolonged match-play. Moreover, it is evident that match-play evokes pronounced and prolonged physiological, neuromuscular and psychological perturbations that may be exacerbated with consecutive days of match-play. Separate to these internal load responses, a collection of non-uniform movement and technical performance changes are reported, though rarely from match-play data. Consequently, direct or causal links between altered physiological or muscle contractile function and subsequent match-play outcomes are lacking. Indeed, emerging evidence seems to infer that players adjust their game strategy, and the resultant execution of stroke play, to accommodate any such deterioration in physiological function. The purpose of this review was to discuss the available literature in terms of the physiological, mechanical and psychological responses that occur during prolonged match-play in the context of their likely effect on match-play performance.
Minett, G. & Duffield, R. 2014, 'Is recovery driven by central or peripheral factors? A role for the brain in recovery following intermittent-sprint exercise.', Frontiers in Physiology, vol. 3, no. 4, pp. 24-28.
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Prolonged intermittent-sprint exercise (i.e. team sports) induce disturbances in skeletal muscle structure and function that are associated with reduced contractile function, a cascade of inflammatory responses, perceptual soreness and a delayed return to optimal physical performance. In this context, recovery from exercise-induced fatigue is traditionally treated from a peripheral viewpoint, with the regeneration of muscle physiology and other peripheral factors the target of recovery strategies. The direction of this research narrative on post-exercise recovery differs to the increasing emphasis on the complex interaction between both central and peripheral factors regulating exercise intensity during exercise performance. Given the role of the central nervous system (CNS) in motor-unit recruitment during exercise, it too may have an integral role in post-exercise recovery. Indeed, this hypothesis is indirectly supported by an apparent disconnect in time-course changes in physiological and biochemical markers resultant from exercise and the ensuing recovery of exercise performance. Equally, improvements in perceptual recovery, even withstanding the physiological state of recovery, may interact with both feed-forward/feed-back mechanisms to influence subsequent efforts. Considering the research interest afforded to recovery methodologies designed to hasten the return of homeostasis within the muscle, the limited focus on contributors to post-exercise recovery from CNS origins is somewhat surprising. Based on this context, the current review aims to outline the potential contributions of the brain to performance recovery after strenuous exercise.
Vickery, W., Dascombe, B., Baker, J., Higam, D., Spratford, W. & Duffield, R. 2014, 'Accuracy and reliability of GPS devices for measurement of sports-specific movement patterns related to cricket, tennis and field-based team sports', Journal of Strength and Conditioning Research, vol. 28, no. 6, pp. 1697-1705.
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The aim of this study was to determine the accuracy and reliability of 5, 10 and 15 Hz global positioning system (GPS) devices. Two male subjects (age: 25.5 &plusmn; 0.7 yr; height: 1.75 &plusmn; 0.01 m; body mass: 74 &plusmn; 5.7 kg) completed ten repetitions of drills replicating movements typical of tennis, cricket and field-based (football) sports. All movements were completed wearing two 5 Hz and 10 Hz MinimaxX and two GPS-Sports 15 Hz GPS devices in a specially designed harness. Criterion movement data for distance and speed was provided from a 22-camera VICON system sampling at 100 Hz. Accuracy was determined using one-way analysis of variance with Tukeys post-hoc tests. Inter-unit reliability was determined using intra-class correlation (ICC) and typical error was estimated as coefficient of variation (CV). Overall, for the majority of distance and speed measures as measured using the 5, 10 and 15 Hz GPS devices, were not significantly different (p>0.05) to the VICON data. Additionally, no improvements in the accuracy or reliability of GPS devices were observed with an increase in the sampling rate. However, the CV for the 5 and 15 Hz devices for distance and speed measures ranged between 3-33%, with increasing variability evident in higher speed zones. The majority of ICC measures possessed a low level of inter-unit reliability (r=-0.350.39). Based on these results, practitioners of these devices should be aware that measurements of distance and speed may be consistently underestimated, regardless of the movements performed.
Duffield, R., Murphy, A., Kellett, A. & Reid, M. 2014, 'Recovery from repeated on-court tennis sessions; combining cold water immersion, compression and sleep recovery interventions.', International Journal of Sports Physiology and Performance, vol. 9, no. 2, pp. 273-282.
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Purpose: To investigate the effects of combining cold-water immersion (CWI), full-body compression garments (CG), and sleep-hygiene recommendations on physical, physiological, and perceptual recovery after 2-a-day on-court training and match-play sessions. Methods: In a crossover design, 8 highly trained tennis players completed 2 sessions of on-court tennis-drill training and match play, followed by a recovery or control condition. Recovery interventions included a mixture of 15 min CWI, 3 h of wearing full-body CG, and following sleep-hygiene recommendations that night, while the control condition involved postsession stretching and no regulation of sleeping patterns. Technical performance (stroke and error rates), physical performance (accelerometry, countermovement jump [CMJ]), physiological (heart rate, blood lactate), and perceptual (mood, exertion, and soreness) measures were recorded from each on-court session, along with sleep quantity each night. Results: While stroke and error rates did not differ in the drill session (P > .05, d < 0.20), large effects were evident for increased time in play and stroke rate in match play after the recovery interventions (P > .05, d > 0.90). Although accelerometry values did not differ between conditions (P > .05, d < 0.20), CMJ tended to be improved before match play with recovery (P > .05, d = 0.90). Furthermore, CWI and CG resulted in faster postsession reductions in heart rate and lactate and reduced perceived soreness (P > .05, d > 1.00). In addition, sleep-hygiene recommendations increased sleep quantity (P > .05, d > 2.00) and maintained lower perceived soreness and fatigue (P < .05, d > 2.00). Conclusions: Mixed-method recovery interventions (CWI and CG) used after tennis sessions increased ensuing time in play and lower-body power and reduced perceived soreness. Furthermore, sleep-hygiene recommendations helped reduce perceived soreness.
Hausswirth, C., Louis, J., Aubry, A., Bonnet, G., Duffield, R. & Le Muer, Y. 2014, 'Evidence of disturbed sleep patterns and increased illness in functionally overreached endurance athletes.', Medicine And Science In Sports And Exercise, vol. 46, no. 5, pp. 1036-1045.
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Purpose: To examine whether i) objective markers of sleep quantity and quality are altered in endurance athletes experiencing overreaching in response to an overload training program and ii) whether potential reduced sleep quality would be accompanied with higher prevalence of upper respiratory tract infections in this population. Methods: Twenty seven trained male triathletes were randomly assigned to either overload (n=18) or normal (CTL, n=9) training groups. Respective training programs included a 1-week moderate training phase, followed by a 3-week period of overload or normal training, respectively and then a subsequent 2-week taper. Maximal aerobic power and oxygen uptake (VO2max) from incremental cycle ergometry were measured after each phase, whilst mood states and incidences of illness were determined from questionnaires. Sleep was monitored every night of the 6 weeks using wristwatch actigraphy. Results: Nine of the 18 overload training group subjects were diagnosed as functionally overreached (F-OR) after the overload period, as based on declines in performance and O2max with concomitant high perceived fatigue (p<0.05), whilst the nine other overload subjects showed no decline in performance (AF, p>0.05). There was a significant time group interaction for sleep duration (SD), sleep efficiency (SE) and immobile time (IT). Only the F-OR group demonstrated a decrease in these three parameters (-7.9&plusmn;6.7%, -1.6&plusmn;0.7% and -7.6&plusmn;6.6%, for SD, SE and IT, respectively, p<0.05), which was reversed during the subsequent taper phase. Higher prevalence of upper respiratory tract infections were also reported in F-OR (67%, 22%, 11% incidence rate, for F-OR, AF and CTL, respectively). Conclusion: This study confirms sleep disturbances and increased illness in endurance athletes who present with symptoms of F-OR during periods of high volume training.
Donges, C.E., Duffield, R., Smith, G., Short, M. & Edge, J.A. 2014, 'Cytokine mRNA expression responses to resistance, aerobic and concurrent exercise in sedentary middle-aged men.', Applied Physiology, Nutrition and Metabolism., vol. 39, no. 2, pp. 130-137.
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Abstract: Concurrent resistance and aerobic exercise (CE) is recommended to ageing populations, though is postulated to induce diminished acute molecular responses. Given that contraction-induced cytokine mRNA expression reportedly mediates remunerative postexercise molecular responses, it is necessary to determine whether cytokine mRNA expression may be diminished after CE. Eight middle-aged men (age, 53.3 &plusmn;1.8 years; body mass index, 29.4 &plusmn; 1.4 kgm-2) randomly completed (balanced for completion order) 8 8 leg extensions at 70% maximal strength (RE), 40 min of cycling at 55% of peak aerobic workload (AE), or (workload-matched) 50% RE and 50% AE (CE). Muscle (vastus lateralis) was obtained pre-exercise, and at 1 h and 4 h postexercise, and analyzed for changes of glycogen concentration, tumor necrosis factor (TNF), TNF receptor-1 and -2 (TNF-R1 and TNF-R2, respectively), interleukin (IL)-6, IL-6R, IL-1, and IL-1 receptor-antagonist (IL-1ra). All exercise modes upregulated cytokine mRNA expression at 1hpostexercise comparably (TNF, TNF-R1, TNF-R2, IL-1, IL-6) (p<0.05). Expression remained elevated at 4hafter RE and AE (p < 0.05), though returned to pre-exercise levels after CE (p > 0.05). Moreover, AE and RE upregulated IL-1 and IL-1ra expression, whereas CE upregulated IL-1 expression only (p < 0.05). Only AE reduced muscle glycogen concentration (p < 0.05), whilst upregulating receptor expression the greatest; though, IL-6R expression remained unchanged after all modes (p > 0.05). In conclusion, in middle-aged men, all modes induced commensurate cytokine mRNA expression at 1 h postexercise; however, only CE resulted in ameliorated expression at 4 h postexercise. Whether the RE or AE components of CE are independently or cumulatively sufficient to upregulate cytokine responses, or whether they collectively inhibit cytokine mRNA expression, remains to be determined.
Mendham, A., Duffield, R., Marino, F. & Coutts, A.J. 2014, 'Differences in post-exercise inflammatory and glucose regulatory response between sedentary indigenous australian and caucasian men completing a single bout of cycling', American Journal Of Human Biology, vol. 26, no. 2, pp. 208-214.
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Objectives: This study compared the acute inflammatory and glucose responses following aerobic exercise in sedentary Indigenous Australian and Caucasian men, matched for fitness and body composition. Methods: Sedentary Indigenous (n510) and Caucasian (n59) Australian men who were free from chronic disease volunteered to participate. Following baseline testing, participants completed a 40 min cycling bout at 80% maximal heart rate. Fasting venous blood was collected pre, 0, 30, 60, and 240 min post-exercise for analysis of glucose, insulin, cortisol, tumor necrosis factor (TNF)-a, interleukin (IL)-1b, IL-6, IL-1 receptor agonist (ra), and C-reactive protein (CRP). Results: Resting TNF-a and glucose concentrations were significantly higher in the Indigenous group (P<0.05). IL- 6 and IL-1ra were elevated for longer in Caucasian (P<0.05), compared with the Indigenous group (P>0.05). The post-exercise (0 min) increase in cortisol and glucose for the Caucasians was higher (P<0.05) than the attenuated responses within the Indigenous group (P>0.05). Conclusions: Despite being matched for fitness and body composition the Indigenous men had elevated resting TNF-a and glucose compared with the Caucasian men, which may have contributed to the suppressed post-exercise anti-inflammatory response of the Indigenous men; however, glucose normalized between groups post-exercise. As such, it is recommended for acute moderate-intensity exercise to be completed daily for long-term improvements in glucose regulation, irrespective of ancestry. Of note, results suggest it to be even more pertinent for exercise to be encouraged for Indigenous Australian men due to their elevated resting glucose levels at a younger age, when compared to the respective Caucasian group.
Zhang, Y., Haddad, A., Su, S.W., Celler, B.G., Coutts, A.J., Duffield, R., Donges, C.E. & Nguyen, H.T. 2014, 'An equivalent circuit model for onset and offset exercise response', BIOMEDICAL ENGINEERING ONLINE, vol. 13.
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Mendham, A.E., Duffield, R., Marino, F. & Coutts, A.J. 2014, 'Small-sided games training reduces CRP, IL-6 and leptin in sedentary, middle-aged men', EUROPEAN JOURNAL OF APPLIED PHYSIOLOGY, vol. 114, no. 11, pp. 2289-2297.
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Murphy, A.P., Duffield, R. & Reid, M. 2014, 'TENNIS FOR PHYSICAL HEALTH: ACUTE AGE- AND GENDER-BASED PHYSIOLOGICAL RESPONSES TO CARDIO TENNIS', JOURNAL OF STRENGTH AND CONDITIONING RESEARCH, vol. 28, no. 11, pp. 3172-3178.
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Murphy, A.P., Duffield, R., Kellett, A. & Reid, M. 2014, 'A Descriptive Analysis of Internal and External Loads for Elite-Level Tennis Drills', INTERNATIONAL JOURNAL OF SPORTS PHYSIOLOGY AND PERFORMANCE, vol. 9, no. 5, pp. 863-870.
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Murphy, A.P., Duffield, R., Kellett, A. & Reid, M. 2014, 'Comparison of athlete-coach perceptions of internal and external load markers for elite junior tennis training.', International journal of sports physiology and performance, vol. 9, no. 5, pp. 751-756.
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PURPOSE: To investigate the discrepancy between coach and athlete perceptions of internal load and notational analysis of external load in elite junior tennis. METHODS: Fourteen elite junior tennis players and 6 international coaches were recruited. Ratings of perceived exertion (RPEs) were recorded for individual drills and whole sessions, along with a rating of mental exertion, coach rating of intended session exertion, and athlete heart rate (HR). Furthermore, total stroke count and unforced-error count were notated using video coding after each session, alongside coach and athlete estimations of shots and errors made. Finally, regression analyses explained the variance in the criterion variables of athlete and coach RPE. RESULTS: Repeated-measures analyses of variance and interclass correlation coefficients revealed that coaches significantly (P < .01) underestimated athlete session RPE, with only moderate correlation (r = .59) demonstrated between coach and athlete. However, athlete drill RPE (P = .14; r = .71) and mental exertion (P = .44; r = .68) were comparable and substantially correlated. No significant differences in estimated stroke count were evident between athlete and coach (P = .21), athlete notational analysis (P = .06), or coach notational analysis (P = .49). Coaches estimated significantly greater unforced errors than either athletes or notational analysis (P < .01). Regression analyses found that 54.5% of variance in coach RPE was explained by intended session exertion and coach drill RPE, while drill RPE and peak HR explained 45.3% of the variance in athlete session RPE. CONCLUSION: Coaches misinterpreted session RPE but not drill RPE, while inaccurately monitoring error counts. Improved understanding of external- and internal-load monitoring may help coach-athlete relationships in individual sports like tennis avoid maladaptive training.
Minett, G.M., Duffield, R., Billaut, F., Cannon, J., Portus, M.R. & Marino, F.E. 2014, 'Cold-water immersion decreases cerebral oxygenation but improves recovery after intermittent-sprint exercise in the heat.', Scandinavian journal of medicine & science in sports, vol. 24, no. 4, pp. 656-666.
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This study examined the effects of post-exercise cooling on recovery of neuromuscular, physiological, and cerebral hemodynamic responses after intermittent-sprint exercise in the heat. Nine participants underwent three post-exercise recovery trials, including a control (CONT), mixed-method cooling (MIX), and cold-water immersion (10&deg;C; CWI). Voluntary force and activation were assessed simultaneously with cerebral oxygenation (near-infrared spectroscopy) pre- and post-exercise, post-intervention, and 1-h and 24-h post-exercise. Measures of heart rate, core temperature, skin temperature, muscle damage, and inflammation were also collected. Both cooling interventions reduced heart rate, core, and skin temperature post-intervention (P<0.05). CWI hastened the recovery of voluntary force by 12.7&plusmn;11.7% (mean&plusmn;SD) and 16.3&plusmn;10.5% 1-h post-exercise compared to MIX and CONT, respectively (P<0.01). Voluntary force remained elevated by 16.1&plusmn;20.5% 24-h post-exercise after CWI compared to CONT (P<0.05). Central activation was increased post-intervention and 1-h post-exercise with CWI compared to CONT (P<0.05), without differences between conditions 24-h post-exercise (P>0.05). CWI reduced cerebral oxygenation compared to MIX and CONT post-intervention (P<0.01). Furthermore, cooling interventions reduced cortisol 1-h post-exercise (P<0.01), although only CWI blunted creatine kinase 24-h post-exercise compared to CONT (P<0.05). Accordingly, improvements in neuromuscular recovery after post-exercise cooling appear to be disassociated with cerebral oxygenation, rather reflecting reductions in thermoregulatory demands to sustain force production.
Coutts, A.J., Mendham, A.E. & Duffield, R. 2014, 'Training and nutritional needs of the older team sport athlete.', CRC Press, New York, pp. 341-362.
Vickery, W., Dascomeb, B., Duffield, R., Kellett, A. & Portus, M. 2013, 'The influence of field size, player number and rulechanges on the physiological responses and movement demands of small-sided games for cricket training', Journal of Sports Sciences, vol. 31, no. 6, pp. 629-638.
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This study investigated the physiological responses and movement demands associated with modified versions of small-sided games for cricket training, termed `Battlezone.
Skein, M., Duffield, R., Minett, G., Snape, A. & Murphy, A. 2013, 'The Effect of Overnight Sleep Deprivation After Competitive Rugby League Matches on Postmatch Physiological and Perceptual Recovery', International Journal of Sports Physiology and Performance, vol. 38, no. 1.
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Purpose: This study examined the effects of overnight sleep deprivation on recovery after competitive rugby league matches.
Guelfi, K.J., Donges, C.E. & Duffield, R. 2013, 'Beneficial effects of 12 weeks of aerobic compared with resistance exercise training on perceived appetite inpreviously sedentary overweight and obese men', Metabolism, vol. 62, pp. 235-243.
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Objective. To investigate the effect of 12 weeks of aerobic (AER) compared with resistance training (RES) on perceived hunger and fullness, together with appetite-related hormones in both the fasted state and postprandially.
Vickery, W., Dascombe, B., Duffield, R., Kellett, A. & Portus, M. 2013, 'Battlezone: An examination of the physiological responses, movement demands and reproducibility of small-sided cricket games', Journal of Sports Sciences, vol. 31, no. 1, pp. 77-86.
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As cricket training typically involves separate skill and conditioning sessions, this study reported on the movement demands, physiological responses and reproducibility of the demands of small-sided cricket games.
Murphy, A., Snape, A., Minett, G., Skein, M. & Duffield, R. 2013, 'The Effect of Post-Match Alcohol Ingestion on Recovery From Competitive Rugby League Matches', Journal Of Strength and Conditioning Research, vol. 27, no. 5, pp. 1304-1312.
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This study investigated the effects of alcohol ingestion on lower-body strength and power and physiological and cognitive recovery after competitive Rugby League matches. Nine male Rugby players participated in 2 matches, followed by 1 of 2 randomized interventions, a control or alcohol ingestion session.
Duffield, R., Coutts, A.J., McCall, A. & Burgess, D. 2013, 'Pre-cooling for football training and competition in hot and humid conditions', European Journal of Sport Science, vol. 13, no. 1, pp. 58-67.
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Pre-cooling studies report positive physiological and performance benefits in laboratory conditions, although research studies have not investigated these reported benefits in ecologically valid team-sport training and competition settings.
Donges, C.E., Duffield, R., Guelfi, K.J., Smith, G.C., Adams, D.R. & Edge, J.A. 2013, 'Comparative effects of single-mode vs. duration-matched concurrent exercise training on body composition, low-grade inflammation, and glucose regulation in sedentary, overweight, middle-aged men', Applied Physiology, Nutrition, and Metabolism, vol. 38, no. 7, pp. 779-788.
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The effect of duration-matched concurrent exercise training (CET) (50% resistance (RET) and 50% endurance (EET) training) on physiological training outcomes in untrained middle-aged men remains to be elucidated. Forty-seven men (age, 48.1 &plusmn; 6.8 years; body mass index, 30.4 &plusmn; 4.1 kgm(-2)) were randomized into 12-weeks of EET (40-60 min of cycling), RET (10 exercises; 3-4 sets 8-10 repetitions), CET (50% serial completion of RET and EET), or control condition. The following were determined: intervention-based changes in fitness and strength; abdominal visceral adipose tissue (VAT), total body fat (TB-FM) and fat-free (TB-FFM) mass; plasma cytokines (C-reactive protein (CRP), tumor necrosis factor-a (TNFa) interleukin-6 (IL-6)); muscle protein content of p110a and glucose transporter 4 (GLUT4); mRNA expression of GLUT4, peroxisome proliferator-activated receptor-? coactivator-1a-, cytochrome c oxidase, hexokinase II, citrate synthase; oral glucose tolerance; and estimated insulin sensitivity. CET promoted commensurate improvements of aerobic capacity and muscular strength and reduced VAT and TB-FM equivalently to EET and RET (p < 0.05), yet only RET increased TB-FFM (p < 0.05). Although TNFa and IL-6 were reduced after all training interventions (p < 0.05), CRP remained unchanged (p > 0.05). EET reduced area under the curve for glucose, insulin, and C-peptide, whilst CET and RET respectively reduced insulin and C-peptide, and C-peptide only (p < 0.05).
Reid, M., Duffield, R., Minett, G., Sibte, N., Murphy, A. & Baker, J. 2013, 'Physiological, Perceptual, and Technical Responses To On-Court Tennis Training On Hard and Clay Courts', Journal of Strength and Conditioning Research, vol. 27, no. 6, pp. 1487-1495.
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The aim of this study was to investigate the effect of court surface (clay vs. hard court) on technical, physiological, and perceptual responses to on-court tennis training. Four high-performance junior male players performed 2 identical training sessions on hard and clay courts, respectively. Sessions included both physical conditioning and technical elements as led by the coach. Each session was filmed for later notational analysis of stroke count and error rates. Furthermore, players wore a global positioning satellite device to measure distance covered during each session, while heart rate, countermovement jump distance, and capillary blood measures of metabolites were measured before, during, and after each session. Additionally, a respective coach and athlete rating of perceived exertion (RPE) were measured after each session. Total duration and distance covered during each session were comparable (p . 0.05; d, 0.20). Although forehand and backhands stroke volume did not differ between sessions (p . 0.05; d , 0.30), large effects for increased unforced and forced errors were present on the hard court (p . 0.05; d . 0.90). Furthermore, large effects for increased heart rate, blood lactate, and RPE values were evident on clay compared with hard courts (p . 0.05; d . 0.90). Additionally, although player and coach RPE on hard courts were similar, there were large effects for coaches to underrate the RPE of players on clay courts (p . 0.05; d . 0.90). In conclusion, training on clay courts results in trends for increased heart rate, lactate, and RPE values, suggesting that sessions on clay courts tend towards higher physiological and perceptual loads than hard courts. Furthermore, coaches seem effective at rating player RPE on hard courts but may underrate the perceived exertion of sessions on clay courts.
Skein, M., Duffield, R., Minett, G.M., Snape, A. & Murphy, A. 2013, 'The Effect of Overnight Sleep Deprivation After Competitive Rugby League Matches on Postmatch Physiological and Perceptual Recovery', INTERNATIONAL JOURNAL OF SPORTS PHYSIOLOGY AND PERFORMANCE, vol. 8, no. 5, pp. 556-564.
Duffield, R., Mccall, A., Coutts, A.J. & Peiffer, J. 2012, 'Hydration, Sweat And Thermoregulatory Responses To Professional Football Training In The Heat', Journal Of Sports Sciences, vol. 30, no. 10, pp. 957-965.
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This study examined the relationship between intensity of training and changes in hydration status, core temperature, sweat rate and composition and fluid balance in professional football players training in the heat. Thirteen professional football playe
Mendham, A., Coutts, A.J. & Duffield, R. 2012, 'The acute effects of aerobic exercise and modified rugby on inflammation and glucose homeostasis within Indigenous Australians', European Journal Of Applied Physiology, vol. 112, no. 11, pp. 3787-3795.
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This study investigated the acute effects of two exercise modes, including cycle ergometry and modified rugby on inflammation and glucose regulation within an Indigenous Australian population. Ten sedentary, untrained Indigenous male participants volunteered to participate and were not clinically diagnosed with cardiovascular or metabolic disorders. Following baseline testing and in a randomized cross-over design participants completed two exercise protocols (cycle ergometry and modified rugby) of 40-min duration separated by 7 days recovery. Fasting venous blood was collected pre, post, 30, 60 and 240 min post exercise for analysis of glucose, insulin, cortisol and inflammatory markers of tumour necrosis factor (TNF)-a, interleukin (IL)-1, IL-6, IL-1 receptor agonist (ra) and C-reactive protein (CRP). IL-6 and IL-1ra were significantly (P < 0.05) increased within the 240 min post-exercise period, without significant differences between protocols (P > 0.05). There were no significant changes within or between protocols for TNF-a, IL-1 and CRP (P > 0.05). A comparison of insulin resistance: homeostasis model (HOMA) between resting and 240 min post exercise shows a change from a baseline value of 4.44 (3.71) to 1.76 (1.67) HOMA in cycle ergometry (P < 0.05) and to 1.54 (1.33) HOMA in modified rugby (P < 0.05), without differences between sessions (P > 0.05). This study identified similar acute inflammatory and glucose regulatory responses between cycle ergometry and modified rugby. Prescribing modified rugby as a mode of physical activity may provide Indigenous populations with a community-based approach to promote increased engagement in physical activity and assist in the acute regulation of glucose disposal and inflammatory cytokines
Pointon, M. & Duffield, R. 2012, 'Cold water immersion recovery following simulated collision sport exercise', Medicine and Science in Sports and Exercise, vol. 44, no. 2, pp. 206-216.
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This investigation examined the effects of cold water immersion (CWI) recovery after simulated collision sport exercise.
Duffield, R., Murphy, A., Snape, A., Minett, G. & Skein, M. 2012, 'Post-match changes in neuromuscular function and the relationship to match demands in amateur rugby league.', Journal Of Science And Medicine In Sport, vol. 15, no. 3, pp. 238-243.
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Objectives: The current study investigated the change in neuromuscular contractile properties following competitive rugby league matches and the relationship with physical match demands.
Pointon, M., Duffield, R., Cannon, J. & Marino, F.E. 2012, 'Cold water immersion recovery following intermittent-sprint exercise in the heat.', European Journal Of Applied Physiology, vol. 112, no. 7, pp. 2483-2494.
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This study examined the effects of cold water immersion (CWI) on recovery of neuromuscular function following simulated team-sport exercise in the heat.
Skein, M., Duffield, R., Kelly, B. & Marino, F.E. 2012, 'The effects of carbohydrate intake and muscle glycogen content on self-paced intermittent-sprint exercise despite no knowledge of carbohydrate manipulation', European Journal Of Applied Physiology, vol. 112, no. 8, pp. 2859-2870.
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The aim of this study was to determine the effects of carbohydrate (CHO) ingestion and muscle glycogen content, without the influence of knowledge of CHO consumption, on intermittent-sprint performance.
Donges, C.E. & Duffield, R. 2012, 'Effects of resistance or aerobic exercise training on total and regional body composition in sedentary overweight middle-aged adults', Applied Physiology, Nutrition and Metabolism., vol. 37, no. 3, pp. 499-509.
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The purpose of this study was to examine the effects of 10 weeks of aerobic endurance training (AET), resistance exercise training (RET), or a control (CON) condition on absolute and relative fat mass (FM) or fat-free mass (FFM) in the total body (TB) and regions of interest (ROIs) of sedentary overweight middle-aged males and females. Following prescreening, 102 subjects underwent anthropometric measurements, dual-energy X-ray absorptiometry, and strength and aerobic exercise testing. Randomized subjects (male RET, n = 16; female RET, n = 19; male AET, n = 16; and female AET, n = 25) completed supervised and periodized exercise programs (AET, 30-50 min cycling at 70%-75% maximal heart rate; RET, 2-4 sets 8-10 repetitions of 5-7 exercises at 70%-75% 1 repetition maximum) or a nonexercising control condition (male CON, n = 13 and female CON, n = 13). Changes in absolute and relative TB-FM and TB-FFM and ROI-FM and ROI-FFM were determined. At baseline, and although matched for age and body mass index, males had greater strength, aerobic fitness, body mass, absolute and relative TB-FFM and ROI-FFM, but reduced absolute and relative TB-FM and ROI-FM, compared with females ( p < 0.05). After training, both female exercise groups showed equivalent or greater relative improvements in strength and aerobic fitness than did the male exercise groups ( p < 0.05); however, the male exercise groups increased TB-FFM and reduced TB-FM more than did the female exercise groups ( p < 0.05). Male AET altered absolute FM more than male RET altered absolute FFM, thus resulting in a greater enhancement of relative FFM. Despite equivalent or greater responses to RET or AET by female subjects, the corresponding respective increases in FFM or reductions in FM were lower than those in males, indicating that a biased dose-response relationship exists between sexes following 10 weeks of exercise training.
Minett, G., Duffield, R., Marino, F.E. & Portus, M.P. 2012, 'Duration-dependent response of pre-cooling for intermittent-sprint exercise in the heat.', European Journal Of Applied Physiology, vol. 112, no. 10, pp. 3655-3666.
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This study examined the effects of pre-cooling duration on performance and neuromuscular function for self-paced intermittent-sprint shuttle running in the heat.
Minett, G., Duffield, R., Kellet, A. & Portus, M.P. 2012, 'Mixed-method pre-cooling reduces physiological demand without improving performance of medium-fast bowling in the heat', Journal of Sports Sciences, vol. 30, no. 9, pp. 907-915.
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This study examined physiological and performance effects of pre-cooling on medium-fast bowling in the heat.
Donges, C.E., Burd, N.A., Duffield, R., Smith, G.C., West, D.D., Short, M.J., Mackenzie, R., Plank, L.D., Shepherd, P.R., Phillips, S.M. & Edge, J.A. 2012, 'Concurrent resistance and aerobic exercise stimulates both myofibrillar and mitochondrial protein synthesis in sedentary middle-aged men', Journal of Applied Physiology, vol. 112, no. 12, pp. 1992-2001.
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Concurrent resistance and aerobic exercise stimulates both myofibrillar and mitochondrial protein synthesis in sedentary middle-aged men.
Minett, G., Duffield, R., Kellett, A. & Portus, M.P. 2012, 'Effects of mixed-method cooling on recovery of medium-fast bowling performance in hot conditions on consecutive days', Journal of Sports Sciences, vol. 30, no. 13, pp. 1387-1396.
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Training and competition demands of medium-fast bowlers are often characterised by multiple and prolonged spells on consecutive days (Orchard, James, Portus, Kountouris, & Dennis, 2009).
Hausswirth, C., Duffield, R., Pournot, H., Bieuzen, F., Louis, J., Brisswalter, J. & Castagna, O. 2012, 'Post-exercise cooling interventions and the effects on exercise-induced heat stress in a thermo-neutral environment.', Applied Physiology, Nutrition and Metabolism., vol. 37, no. 5, pp. 965-975.
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The aim of this study was to examine the effects of cool water immersion (20 ?C; CWI) while wearing a cooling jacket (Cryovest;V) and a passive control (PAS) as recovery methods on physiological and thermoregulatory responses between 2 exercise bouts in temperate conditions. Nine well-trained male cyclists performed 2 successive bouts of 45 min of endurance cycling exercise in a temperate environment (20 ?C) separated by 25 min of the respective recovery interventions. Capillary blood samples were obtained to measure lactate (La-), sodium (Na+), bicarbonate (HCO3-) concentrations and pH, whilst body mass loss (BML), core temperature ( Tcore), skin temperature ( Tskin), heart rate (HR), oxygen uptake , and minute ventilation were measured before (Pre), immediately after the first exercise bout (Ex1), the recovery (R), and after the second exercise bout (Ex2). V and CWI both resulted in a reduction of Tskin at R (-2.1 ? 0.01 ?C and -11.6 ? 0.01 ?C, respectively, p < 0.01). Despite no difference in final values post-Ex2 ( p > 0.05), V attenuated the rise in HR, minute ventilation, and oxygen uptake from Ex1 to Ex2, while Tcore and Tskin were significantly lower following the second session ( p < 0.05). Further, CWI was also beneficial in lowering Tcore, Tskin, and BML, while a rise in Na+ was observed following Ex2 ( p < 0.05). Overall results indicate that cooling interventions (V and CWI) following exercise in a temperate environment provide a reduction in thermal strain during ensuing exercise bouts.
Skein, M., Duffield, R., Cannon, J. & Marino, F.E. 2012, 'Self-paced intermittent-sprint performance and pacing strategies following respective pre-cooling and heating.', European Journal Of Applied Physiology, vol. 112, no. 1, pp. 253-266.
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This study examined the effects of pre-exercise cooling and heating on neuromuscular function, pacing and intermittent-sprint performance in the heat.
Minett, G., Duffield, R., Marino, F. & Portus, M. 2011, 'Volume-Dependent Response of Precooling for Intermittent-Sprint Exercise in the Heat', Medicine and Science in Sports and Exercise, vol. 43, no. 9, pp. 1760-1769.
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Purpose: This study aimed to assess the effects of precooling volume on neuromuscular function and performance in free-paced intermittent-sprint exercise in the heat.
Skein, M., Duffield, R., Edge, J., Short, M. & Mundell, T. 2011, 'Intermittent-Sprint Performance and Muscle Glycogen after 30 h of Sleep Deprivation', Medicine And Science In Sports And Exercise, vol. 43, no. 7, pp. 1301-1311.
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The aim of this study was to determine the effects of 30 h of sleep deprivation on consecutive-day intermittent-sprint performance and muscle glycogen content.
Mendham, A., Donges, C., Liberts, E. & Duffield, R. 2011, 'Effects of mode and intensity on the acute exercise-induced IL-6 and CRP responses in a sedentary, overweight population', European Journal Of Applied Physiology, vol. 111, pp. 1035-1045.
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This study sought to compare the respective effects of resistance or aerobic exercise of higher or lower intensities on the acute plasma interleukin-6 (IL-6) and C-reactive protein (CRP) response in a sedentary, middleaged, disease-free cohort.
Pointon, M., Duffield, R., Cannon, J. & Marino, F. 2011, 'Cold application for neuromuscular recovery following intense lower-body exercise', European Journal Of Applied Physiology, vol. 111, no. 12, pp. 2977-2986.
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This study examined the effects of cold therapy (COLD) on recovery of voluntary and evoked contractile properties following high-intensity, muscle-damaging and fatiguing exercise.
Pournot, H., Bieuzen, F., Duffield, R., Lepretre, P., Cozzolino, C. & Hausswirth, C. 2011, 'Short term effects of various water immersions on recovery from exhaustive intermittent exercise', European Journal Of Applied Physiology, vol. 111, pp. 1287-1295.
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Duffield, R., Bird, S. & Ballard, R. 2011, 'Field-based pre-cooling for on-court tennis conditioning training in the heat', Journal of Sports Science and Medicine, vol. Online, pp. 376-384.
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The present study investigated the effects of pre-cooling for oncourt, tennis-specific conditioning training in the heat.
Skein, M. & Duffield, R. 2010, 'The effects of fluid ingestion on free-paced intermittent-sprint performance and pacing strategies in the heat', Journal of Sports Sciences, vol. 28, no. 3, pp. 299-307.
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The purpose of this study was to examine the effects of fluid ingestion on pacing strategies and performance during intermittent-sprint exercise in the heat. Nine male rugby players performed a habituation session and 2650-min intermittent-sprint protocols at a temperature of 318C, either with or without fluid.
Coutts, A.J. & Duffield, R. 2010, 'Validity and reliability of GPS devices for measuring movement demands of team sports', Journal of Science and Medicine in Sport, vol. 13, no. 1, pp. 133-135.
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There is limited information regarding the validity and reliability of global positioning system (GPS) devices for measuring movement during team sports. The aim of this study was to assess the validity and intra-model reliability of different GPS devices for quantifying high-intensity, intermittent exercise performance. Two moderately trained males each completed eight bouts of a standard circuit that consisted of six laps around a 128.5-m course involving intermittent exercise. Distance and speed were collected concurrently at 1-Hz using six GPS devices (2 SPI-10, 2 SPI Elite and 2 WiSPI, GPSports, Canberra, Australia). Performance measures were: (1) total distance covered for each bout and each lap; (2) high-intensity running distance (>14.4kmh&acirc;1, HIR); very high-intensity running distance (>20kmh&acirc;1, VHIR) during each bout. Peak speed was also measured during a 20-m sprint at the start of each lap of the circuit (N=192). Actual distance was measured using a measuring tape. Mean (&Acirc;&plusmn;SD) circuit total distance was significantly different between each of the GPS devices (P<0.001); however, all devices were within 5m of the actual lap distance and had a good level of reliability (coefficient of variation (CV) <5%). The CV for total distance (3.6&acirc;7.1%) and peak speed (2.3&acirc;5.8%) was good-to-moderate, but poor for HIR (11.2&acirc;32.4%) and VHIR (11.5&acirc;30.4%) for all GPS devices. These results show that the GPS devices have an acceptable level of accuracy and reliability for total distance and peak speeds during high-intensity, intermittent exercise, but may not be provide reliable measures for higher intensity activities.
Duffield, R., Green, R., Castle, P. & Maxwell, N. 2010, 'Precooling Can Prevent the Reduction of Self-Paced Exercise Intensity in the Heat', Medicine And Science In Sports And Exercise, vol. 42, no. 3, pp. 577-584.
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This study investigated the effects of precooling on performance and pacing during self-paced endurance cycling in the heat and, further, the effects of cooling on contractile function as a mechanism for performance changes.
Donges, C., Duffield, R. & Drinkwater, E. 2010, 'Effects of Resistance or Aerobic Exercise Training on Interleukin-6, C-Reactive Protein, and Body Composition', Medicine And Science In Sports And Exercise, vol. 42, no. 2, pp. 304-313.
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To determine the effects of 10 wk of resistance or aerobic exercise training on interleukin-6 (IL-6) and C-reactive protein (CRP).
Minett, G., Duffield, R. & Bird, S. 2010, 'Effects of Acute Multinutrient Supplementation on Rugby Union Game Performance and Recovery', International Journal of Sports Physiology and Performance, vol. 5, no. 1, pp. 27-41.
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To investigate the effects of an acute multinutrient supplement on game based running performance, peak power output, anaerobic by-products, hormonal profiles, markers of muscle damage, and perceived muscular soreness before, immediately after, and 24 h following competitive rugby union games.
Duffield, R., Cannon, J. & King, M. 2010, 'The effects of compression garments on recovery of muscle performance following high-intensity sprint and plyometric exercise', Journal Of Science And Medicine In Sport, vol. 13, no. 1, pp. 136-140.
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This study compared the effects of compression garments on recovery of evoked and voluntary performance following fatiguing exercise. Eleven participants performed 2 sessions separated by 7 days, with and without lower-body compression garments during and 24 h postexercise.
Duffield, R., Reid, M., Baker, J. & Spratford, W. 2010, 'Accuracy and reliability of GPS devices for measurement of movement patterns in confined spaces for court-based sports', Journal Of Science And Medicine In Sport, vol. 13, pp. 523-525.
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The aim of this study was to assess the accuracy and reliability of global positioning system (GPS) measures of distance and speed, compared to a high-resolution motion analysis system, for confined movement patterns used in many court-based sports.
Duffield, R., Coutts, A.J. & Quinn, J. 2009, 'Core temperature responses and match running performance during intermittent-sprint exercise competition in warm conditions', Journal Of Strength and Conditioning Research, vol. 23, no. 4, pp. 1238-1244.
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This study investigated the thermoregulatory responses and match running performance of elite team sport competitors (Australian Rules football) during preseason games in a warm environment. During 2 games in dry bulb temperatures above 29&deg;C (>27&deg;C wet bulb globe temperature), 10 players were monitored for core temperature (T^sub core^) via a telemetric capsule, in-game motion patterns, blood lactate ([La^sup -^]), body mass changes, urine specific gravity, and pre- and postgame vertical jump performance. The results showed that peak T^sub core^ was achieved during the final quarter at 39.3 &plusmn; 0.7&deg;C and that several players reached values near 40.0&deg;C. Further, the largest proportion of the total rise in T^sub core^ (2.1 &plusmn; 0.7&deg;C) occurred during the first quarter of the match, with only small increases during the remainder of the game. The game distance covered was 9.4 &plusmn; 1.5 km, of which 2.7 &plusmn; 0.9 km was at high-intensity speeds (>14.4 km-h^sup -1^). The rise in T^sub core^ was correlated with first-quarter high-intensity running velocity (r = 0.72) and moderate-intensity velocity (r = 0.68), second-quarter T^sub core^ and low-intensity activity velocity (r = -0.90), second-quarter T^sub core^ and moderate-intensity velocity (r = 0.88), fourth-quarter rise in T^sub core^ and very-high-intensity running distance (r = 0.70), and fourth-quarter T^sub core^ and moderate-intensity velocity (r = 0.73). Additional results included mean game [La^sup -^] values of 8.7 &plusmn; 0.1 mmol*L^sup -1^, change in body mass of 2.1 &plusmn; 0.8 kg, and no change (p > 0.05) in pre- to postgame vertical jump. These findings indicate that the plateau in T^sub core^ may be regulated by the reduction in lowintensity activity and that pacing strategies may be employed during competitive team sports in the heat to ensure control of the internal heat load.
King, M. & Duffield, R. 2009, 'The effects of recovery interventions on consecutive days of intermittent-sprint exercise', Journal Of Strength and Conditioning Research, vol. 23, no. 6, pp. 1795-1802.
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The purpose of this study was to compare four recovery interventions following simulated team sport, intermittent-sprint exercise on consecutive days. Ten female netball players performed four randomized sessions of a simulated netball exercise circuit on consecutive days.
Duffield, R., Steinbacher, G. & Fairchild, T. 2009, 'The use of mixed-method, part-body pre-cooling procedures for team-sport athletes training in the heat', Journal of Strength and Conditioning Research, vol. 23, no. 9, pp. 2524-2532.
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The current study investigated the effects of a pre-cooling intervention on physiological and performance responses to team-sport training in the heat. Seven male lacrosse players performed a familiarization session and 2 randomized, counterbalanced sessions consisting of a 30-minute intermittent-sprint conditioning session.
Duffield, R., King, M. & Skein, M. 2009, 'Recovery of Voluntary and Evoked Muscle Performance Following Intermittent-Sprint Exercise in the Heat', INTERNATIONAL JOURNAL OF SPORTS PHYSIOLOGY AND PERFORMANCE, vol. 4, no. 2, pp. 254-268.
Duffield, R., Carney, M. & Karppinen, S. 2009, 'Physiological responses and bowling performance during repeated spells of medium-fast bowling', JOURNAL OF SPORTS SCIENCES, vol. 27, no. 1, pp. 27-35.
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Duffield, R., Edge, J., Merrells, R., Hawke, E., Barnes, M., Simcock, D. & Gill, N. 2008, 'The Effects of Compression Garments on Intermittent Exercise Performance and Recovery on Consecutive Days', INTERNATIONAL JOURNAL OF SPORTS PHYSIOLOGY AND PERFORMANCE, vol. 3, no. 4, pp. 454-468.
Duffield, R. 2008, 'Cooling interventions for the protection and recovery of exercise performance from exercise-induced heat stress.', Medicine and sport science, vol. 53, pp. 89-103.
The aim of this chapter is to review the literature on the use of cooling interventions in the protection of and recovery of performance from exercise-induced heat stress. This chapter will deal primarily with the effects of pre-cooling on the improvement in exercise performance and the effects of post-exercise cooling on recovery. While pre-cooling has received much research attention, the mechanisms resulting in enhanced performance remain equivocal and moreover, pre-cooling has previously only been considered effective for endurance performance. More recent research describing the effects of pre-cooling on exercise performance and prevention of heat-related illness will be examined. This chapter will also deal with the suppression of exercise performance following heat stress and the use of cooling methods to improve the recovery of muscle function and subsequent exercise performance. Given the use of cold water immersion as a recovery practice of many athletes, a surprising lack of research has been conducted on the effects of cooling as a recovery tool from heat stress. As such, this chapter will discuss the use of cooling interventions on both the prevention of heat stress and recovery of performance from exercise-induced heat stress.
Duffield, R. & Drinkwater, E.J. 2008, 'Time-motion analysis of Test and One-Day international cricket centuries', JOURNAL OF SPORTS SCIENCES, vol. 26, no. 5, pp. 457-464.
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Duffield, R. & Bishop, D. 2008, 'VO2 responses to running speeds above VO2max', INTERNATIONAL JOURNAL OF SPORTS MEDICINE, vol. 29, no. 6, pp. 494-499.
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Reid, M., Duffield, R., Dawson, B., Baker, J. & Crespo, M. 2008, 'Quantification of the physiological and performance characteristics of on-court tennis drills', BRITISH JOURNAL OF SPORTS MEDICINE, vol. 42, no. 2, pp. 146-151.
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Duffield, R. & Coutts, A.J. 2007, 'Pre-cooling for team-sports: Does it work and is it required?', Sports Coach, vol. 29, no. 3, pp. 29-30.
Duffield, R. & Marino, F.E. 2007, 'Effects of pre-cooling procedures on intermittent-sprint exercise performance in warm conditions', EUROPEAN JOURNAL OF APPLIED PHYSIOLOGY, vol. 100, no. 6, pp. 727-735.
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Duffield, R. & Portus, M. 2007, 'Comparison of three types of full-body compression garments on throwing and repeat-sprint performance in cricket players', BRITISH JOURNAL OF SPORTS MEDICINE, vol. 41, no. 7, pp. 409-414.
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Duffield, R., Edge, J., Bishop, D. & Goodman, C. 2007, 'The relationship between the (VO2)-O-. Slow component, muscle metabolites and performance during very-heavy exhaustive exercise', JOURNAL OF SCIENCE AND MEDICINE IN SPORT, vol. 10, no. 3, pp. 127-134.
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Duffield, R., Bishop, D. & Dawson, B. 2006, 'Comparison of the VO(2) response to 800-m, I 500-m and 3 000-m track running events', JOURNAL OF SPORTS MEDICINE AND PHYSICAL FITNESS, vol. 46, no. 3, pp. 353-360.
Spencer, M., Bishop, D., Dawson, B., Goodman, C. & Duffield, R. 2006, 'Metabolism and performance in repeated cycle sprints: Active versus passive recovery', MEDICINE AND SCIENCE IN SPORTS AND EXERCISE, vol. 38, no. 8, pp. 1492-1499.
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Duffield, R., Edge, J. & Bishop, D. 2006, 'Effects of high-intensity interval training on the VO2 response during severe exercise', JOURNAL OF SCIENCE AND MEDICINE IN SPORT, vol. 9, no. 3, pp. 249-255.
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Duffield, R., Dawson, B. & Goodman, C. 2005, 'Energy system contribution to 1500-and 3000-metre track running', JOURNAL OF SPORTS SCIENCES, vol. 23, no. 10, pp. 993-1002.
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Duffield, R., Dawson, B. & Goodman, C. 2005, 'Energy system contribution to 400-metre and 800-metre track running', JOURNAL OF SPORTS SCIENCES, vol. 23, no. 3, pp. 299-307.
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Duffield, R., Dawson, B. & Goodman, C. 2004, 'Energy system contribution to 100-m and 200-m track running events', JOURNAL OF SCIENCE AND MEDICINE IN SPORT, vol. 7, no. 3, pp. 302-313.
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Duffield, R., Dawson, B., Pinnington, H. & Wong, P. 2004, 'Accuracy and reliabillity of a Cosmed K4b(2) portable gas analysis system', JOURNAL OF SCIENCE AND MEDICINE IN SPORT, vol. 7, no. 1, pp. 11-22.
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Duffield, R., Dawson, B., Bishop, D., Fitzsimons, M. & Lawrence, S. 2003, 'Effect of wearing an ice cooling jacket on repeat sprint performance in warm/humid conditions', BRITISH JOURNAL OF SPORTS MEDICINE, vol. 37, no. 2, pp. 164-169.
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Bishop, D., Spencer, M., Duffield, R. & Lawrence, S. 2001, 'The validity of a repeated sprint ability test', JOURNAL OF SCIENCE AND MEDICINE IN SPORT, vol. 4, no. 1, pp. 19-29.
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