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Jonathan D.C. Leeder, Ken A. van Someren, David Gaze, Andrew Jewell, Nawed I.K. Deshmukh, Iltaf Shah, James Barker and Glyn Howatson

Purpose:

This investigation aimed to ascertain a detailed physiological profile of recovery from intermittentsprint exercise of athletes familiar with the exercise and to investigate if athletes receive a protective effect on markers of exercise-induced muscle damage (EIMD), inflammation, and oxidative stress after a repeated exposure to an identical bout of intermittent-sprint exercise.

Methods:

Eight well-trained male team-sport athletes of National League or English University Premier Division standard (mean ± SD age 23 ± 3 y, VO2max 54.8 ± 4.6 mL · kg−1 · min−1) completed the Loughborough Intermittent Shuttle Test (LIST) on 2 occasions, separated by 14 d. Maximal isometric voluntary contraction (MIVC), countermovement jump (CMJ), creatine kinase (CK), C-reactive protein (CRP), interleukin-6 (IL-6), F2-isoprostanes, and muscle soreness (DOMS) were measured before and up to 72 h after the initial and repeated LISTs.

Results:

MIVC, CMJ, CK, IL-6, and DOMS all showed main effects for time (P < .05) after the LIST, indicating that EIMD was present. DOMS peaked at 24 h after LIST 1 (110 ± 53 mm), was attenuated after LIST 2 (56 ± 39 mm), and was the only dependent variable to demonstrate a reduction in the second bout (P = .008). All other markers indicated that EIMD did not differ between bouts.

Conclusion:

Well-trained games players experienced EIMD after exposure to both exercise tests, despite being accustomed to the exercise type. This suggests that well-trained athletes receive a very limited protective effect from the first bout.

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Mark Hayes, Paul C. Castle, Emma Z. Ross and Neil S. Maxwell

Purpose:

To examine the effect of a hot humid (HH) compared with a hot dry (HD) environment, matched for heat stress, on intermittent-sprint performance. In comparison with HD, HH environments compromise evaporative heat loss and decrease exercise tolerance. It was hypothesized that HH would produce greater physiological strain and reduce intermittent-sprint exercise performance compared with HD.

Method:

Eleven male team-sport players completed the cycling intermittent-sprint protocol (CISP) in 3 conditions, temperate (TEMP; 21.2°C ± 1.3°C, 48.6% ± 8.4% relative humidity [rh]), HH (33.7°C ± 0.5°C, 78.2% ± 2.3% rh), and HD (40.2°C ± 0.2°C, 33.1% ± 4.9% rh), with both heat conditions matched for heat stress.

Results:

All participants completed the CISP in TEMP, but 3 failed to completed the full protocol of 20 sprints in HH and HD. Peak power output declined in all conditions (P < .05) but was not different between any condition (sprints 1–14 [N = 11]: HH 1073 ± 150 W, HD 1104 ± 127 W, TEMP, 1074 ± 134; sprints 15–20 [N = 8]: HH 954 ± 114 W, HD 997 ± 115 W, TEMP 993 ± 94; P > .05). Physiological strain was not significantly different in HH compared with HD, but HH was higher than TEMP (P < .05).

Conclusion:

Intermittent-sprint exercise performance of 40 min duration is impaired, but it is not different in HH and HD environments matched for heat stress despite evidence of a trend toward greater physiological strain in an HH environment.

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Rob Duffield, Monique King and Melissa Skein

Purpose:

This study investigated the effects of hot conditions on the acute recovery of voluntary and evoked muscle performance and physiological responses following intermittent exercise.

Methods:

Seven youth male and six female team-sport athletes performed two sessions separated by 7 d, involving a 30-min exercise protocol and 60-min passive recovery in either 22°C or 33°C and 40% relative humidity. The exercise protocol involved a 20-s maximal sprint every 5 min, separated by constant-intensity exercise at 100 W on a cycle ergometer. Maximal voluntary contraction (MVC) and a resting evoked twitch (Pf) of the right knee extensors were assessed before and immediately following exercise and again 15, 30, and 60 min post exercise, and capillary blood was obtained at the same time points to measure lactate, pH, and HCO3. During and following exercise, core temperature, heart rate and rating of perceived exertion (RPE) were also measured.

Results:

No differences (P = 0.73 to 0.95) in peak power during repeated sprints were present between conditions. Post exercise MVC was reduced (P < .05) in both conditions and a moderate effect size (d = 0.60) indicated a slower percentage MVC recovered by 60 min in the heat (83 ± 10 vs 74 ± 11% recovered). Both heart rate and core temperature were significantly higher (P < .05) during recovery in the heat. Capillary blood values did not differ between conditions at any time point, whereas sessional RPE was higher 60 min post exercise in the heat.

Conclusions:

The current data suggests that passive recovery in warm temperatures not only delays cardiovascular and thermal recovery, but may also slow the recovery of MVC and RPE.

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Rob Duffield, Johann Edge, Robert Merrells, Emma Hawke, Matt Barnes, David Simcock and Nicholas Gill

Purpose:

The aim of this study was to determine whether compression garments improve intermittent-sprint performance and aid performance or self-reported recovery from high-intensity efforts on consecutive days.

Methods:

Following familiarization, 14 male rugby players performed two randomized testing conditions (with or without garments) involving consecutive days of a simulated team sport exercise protocol, separated by 24 h of recovery within each condition and 2 weeks between conditions. Each day involved an 80-min high-intensity exercise circuit, with exercise performance determined by repeated 20-m sprints and peak power on a cart dynamometer (single-man scrum machine). Measures of nude mass, heart rate, skin and tympanic temperature, and blood lactate (La) were recorded throughout each day; also, creatine kinase (CK) and muscle soreness were recorded each day and 48 h following exercise.

Results:

No differences (P = .20 to 0.40) were present between conditions on either day of the exercise protocol for repeated 20-m sprint efforts or peak power on a cart dynamometer. Heart rate, tympanic temperature, and body mass did not significantly differ between conditions; however, skin temperature was higher under the compression garments. Although no differences (P = .50) in La or CK were present, participants felt reduced levels of perceived muscle soreness in the ensuing 48 h postexercise when wearing the garments (2.5 ± 1.7 vs 3.5 ± 2.1 for garment and control; P = .01).

Conclusions:

The use of compression garments did not improve or hamper simulated team-sport activity on consecutive days. Despite benefits of reduced self-reported muscle soreness when wearing garments during and following exercise each day, no improvements in performance or recovery were apparent.

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Melissa Skein, Rob Duffield, Geoffrey M. Minett, Alanna Snape and Alistair Murphy

Purpose:

This study examined the effects of overnight sleep deprivation on recovery after competitive rugby league matches.

Methods:

Eleven male amateur rugby league players played 2 competitive matches, followed by either a normal night’s sleep (~8 h; CONT) or a sleep-deprived night (~0 h; SDEP) in a randomized fashion. Testing was conducted the morning of the match, immediately postmatch, 2 h postmatch, and the next morning (16 h postmatch). Measures included countermovement-jump (CMJ) distance, knee-extensor maximal voluntary contraction (MVC) and voluntary activation (VA), venous-blood creatine kinase (CK) and C-reactive protein (CRP), perceived muscle soreness, and a word–color recognition cognitive-function test. Percent change between postmatch and 16-h postmatch was reported to determine the effect of the intervention the next morning.

Results:

Large effects indicated a greater postmatch to 16-h-postmatch percentage decline in CMJ distance after SDEP than in CONT (P = .10–.16, d = 0.95–1.05). Similarly, the percentage decline in incongruent word–color reaction times was increased in SDEP trials (P = .007, d = 1.75). Measures of MVC did not differ between conditions (P = .40–.75, d = 0.13–0.33), although trends for larger percentage decline in VA were detected in SDEP (P = .19, d = 0.84). Furthermore, large effects indicated higher CK and CRP responses 16 h postmatch in SDEP than in CONT (P = .11–.87, d = 0.80–0.88).

Conclusions:

Sleep deprivation negatively affected recovery after a rugby league match, specifically impairing CMJ distance and cognitive function. Practitioners should promote adequate postmatch sleep patterns or adjust training demands the next day to accommodate the altered physical and cognitive state after sleep deprivation.

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Katy E. Griggs, Christof A. Leicht, Michael J. Price and Victoria L. Goosey-Tolfrey

Purpose:

Individuals with a spinal-cord injury have impaired thermoregulatory control due to a loss of sudomotor and vasomotor effectors below the lesion level. Thus, individuals with high-level lesions (tetraplegia) possess greater thermoregulatory impairment than individuals with lower-level lesions (paraplegia). Previous research has not reflected the intermittent nature and modality of wheelchair court sports or replicated typical environmental temperatures. Hence, the purpose of this study was to investigate the thermoregulatory responses of athletes with tetraplegia and paraplegia during an intermittent-sprint protocol (ISP) and recovery in cool conditions.

Methods:

Sixteen wheelchair athletes, 8 with tetraplegia (TP, body mass 65.2 ± 4.4 kg) and 8 with paraplegia (body mass 68.1 ± 12.3 kg), completed a 60-min ISP in 20.6°C ± 0.1°C, 39.6% ± 0.8% relative humidity on a wheelchair ergometer, followed by 15 min of passive recovery. Core temperature (T core) and mean (T sk) and individual skin temperatures were measured throughout.

Results:

Similar external work (P = .70, ES = 0.20) yet a greater T core (P < .05, ES = 2.27) and T sk (P < .05, ES = 1.50) response was demonstrated by TP during the ISP.

Conclusions:

Despite similar external work, a marked increase in Tcore in TP during exercise and recovery signifies that thermoregulatory differences between the groups were predominantly due to differences in heat loss. Further increases in thermal strain were not prevented by the active and passive recovery between maximal-effort bouts of the ISP, as T core continually increased throughout the protocol in TP.

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Neil S. Maxwell, Richard W.A. Mackenzie and David Bishop

Purpose:

To examine the effect of hypohydration on physiological strain and intermittent sprint exercise performance in the heat (35.5 ± 0.6°C, 48.7 ± 3.4% relative humidity).

Methods:

Eight unacclimatized males (age 23.4 ± 6.2 y, height 1.78 ± 0.04 m, mass 76.8 ± 7.7 kg) undertook three trials, each over two days. On day 1, subjects performed 90 min of exercise/heat-induced dehydration on a cycle ergometer, before following one of three rehydration strategies. On day 2, subjects completed a 36-min cycling intermittent sprint test (IST) with a -0.62 ± 0.74% (euhydrated, EUH), -1.81 (0.99)% (hypohydrated1, HYPO1), or -3.88 ± 0.89% (hypohydrated2, HYPO2) body mass defcit.

Results:

No difference was observed in average total work (EUH, 3790 ± 556 kJ; HYPO1, 3785 ± 628 kJ; HYPO2, 3647 ± 339 kJ, P = 0.418), or average peak power (EUH, 1315 ± 129 W; HYPO1, 1304 ± 175 W; HYPO2, 1282 ± 128 W, P = 0.356) between conditions on day 2. Total work and peak power output in the sprint immediately following an intense repeated sprint bout during the IST were lower in the HYPO2 condition. Physiological strain index was greater in the HYPO2 vs. the EUH condition, but without changes in metabolic markers.

Conclusion:

A greater physiological strain was observed with the greatest degree of hypohydration; however, sprint performance only diminished in the most hypohydrated state near the end of the IST, following an intense bout of repeating sprinting.

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Jessica M. Stephens, Ken Sharpe, Christopher Gore, Joanna Miller, Gary J. Slater, Nathan Versey, Jeremiah Peiffer, Rob Duffield, Geoffrey M. Minett, David Crampton, Alan Dunne, Christopher D. Askew and Shona L. Halson

.1136/bjsm.2009.065565 3. Minett GM , Duffield R , Billaut F , Cannon J , Portus MR , Marino FE . Cold-water immersion decreases cerebral oxygenation but improves recovery after intermittent-sprint exercise in the heat . Scand J Med Sci Sports . 2014 ; 24 ( 4 ): 656 – 666 . PubMed ID

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Jeffrey R. Doeringer, Megan Colas, Corey Peacock and Dustin R. Gatens

00421-011-1924-1 21445604 10. Pointon M , Duffield R , Cannon J , Marino F . Cold water immersion recovery following intermittent-sprint exercise in the heat . Eur J Appl Physiol . 2012 ; 112 : 2483 – 2494 . PubMed doi:10.1007/s00421-011-2218-3 10.1007/s00421-011-2218-3 22057508 11

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Cathal Cassidy, Kieran Collins and Marcus Shortall

), 60 – 69 . PubMed ID: 10200060 doi:10.1123/ijsn.9.1.60 10.1123/ijsn.9.1.60 Skein , M. , Duddfield , R. , Kelly , B.T. , & Marino , F.E. ( 2012 ). The effects of carbohydrate intake and muscle glycogen content on self-paced intermittent-sprint exercise despite no knowledge of carbohydrate