United Kingdom Sports Council

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United Kingdom Sports Council

London, United Kingdom

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Crewther B.T.,Imperial College London | Cook C.J.,Imperial College London | Cook C.J.,University of Bath | Gaviglio C.M.,University of Queensland | And 2 more authors.
Journal of Strength and Conditioning Research | Year: 2012

The objective of this study was to determine if salivary free testosterone can predict an athlete's performance during back squats and sprints over time and the influence baseline strength on this relationship. Ten weight-trained male athletes were divided into 2 groups based on their 1 repetition maximum (1RM) squats, good squatters (1RM > 2.0 × body weight, n = 5) and average squatters (1RM < 1.9 ×s body weight, n = 5). The good squatters were stronger than the average squatters (p < 0.05). Each subject was assessed for squat 1RM and 10-m sprint times on 10 separate occasions over a 40-day period. A saliva sample was collected before testing and assayed for free testosterone and cortisol. The pooled testosterone correlations were strong and significant in the good squatters (r = 0.92 for squats, r = 20.87 for sprints, p < 0.01), but not significant for the average squatters (r = 0.35 for squats, r = 20.18 for sprints). Cortisol showed no significant correlations with 1RM squat and 10-m sprint performance, and no differences were identified between the 2 squatting groups. In summary, these results suggest that free testosterone is a strong individual predictor of squat and sprinting performance in individuals with relatively high strength levels but a poor predictor in less strong individuals. This information can assist coaches, trainers, and performance scientists working with stronger weight-trained athletes, for example, the preworkout measurement of free testosterone could indicate likely training outcomes or a readiness to train at a certain intensity level, especially if real-time measurements are made. Our results also highlight the need to separate group and individual hormonal data during the repeated testing of athletes with variable strength levels. © 2012 National Strength and Conditioning Association.


Cook C.J.,United Kingdom Sports Council | Cook C.J.,Imperial College London | Cook C.J.,University of Bath | Beaven C.M.,United Kingdom Sports Council | And 2 more authors.
Journal of Strength and Conditioning Research | Year: 2013

Eccentric and overspeed training modalities are effective in improving components of muscular power. Eccentric training induces specific training adaptations relating to muscular force, whereas overspeed stimuli target the velocity component of power expression. We aimed to compare the effects of traditional or eccentric training with volume-matched training that incorporated overspeed exercises. Twenty team-sport athletes performed 4 counterbalanced 3-week training blocks consecutively as part of a preseason training period: (1) traditional resistance training; (2) eccentric-only resistance training; (3) traditional resistance training with overspeed exercises; and (4) eccentric resistance training with overspeed exercises. The overspeed exercises performed were assisted countermovement jumps and downhill running. Improvements in bench press (15.0 ± 5.1 kg; effect size [ES]: 1.52), squat (19.5 ± 9.1 kg; ES: 1.12), and peak power in the countermovement jump (447 ± 248 W; ES: 0.94) were observed following the 12-week training period. Greater strength increases were observed as a result of the eccentric training modalities (ES: 0.72-1.09) with no effect of the overspeed stimuli on these measures (p > 0.05). Eccentric training with overspeed stimuli was more effective than traditional resistance training in increasing peak power in the countermovement jump (94 ± 55 W; ES: 0.95). Eccentric training induced no beneficial training response in maximal running speed (p > 0.05); however, the addition of overspeed exercises salvaged this relatively negative effect when compared with eccentric training alone (0.03 ± 0.01 seconds; ES: 1.33). These training results achieved in 3-week training blocks suggest that it is important to target-specific aspects of both force and movement velocity to enhance functional measures of power expression. © 2013 National Strength and Conditioning Association.


Beaven C.M.,United Kingdom Sports Council | Beaven C.M.,Mittuniversitetet | Cook C.J.,United Kingdom Sports Council | Cook C.J.,Imperial College London | And 4 more authors.
Applied Physiology, Nutrition and Metabolism | Year: 2012

Repeated cycles of vascular occlusion followed by reperfusion initiate a protective mechanism that acts to mitigate future cell injury. Such ischemic episodes are known to improve vasodilation, oxygen utilization, muscle function, and have been demonstrated to enhance exercise performance. Thus, the use of occlusion cuffs represents a novel intervention that may improve subsequent exercise performance. Fourteen participants performed an exercise protocol that involved lower-body strength and power tests followed by repeated sprints. Occlusion cuffs were then applied unilaterally (2 × 3-min per leg) with a pressure of either 220 (intervention) or 15 mm Hg (control). Participants immediately repeated the exercise protocol, and then again 24 h later. The intervention elicited delayed beneficial effects (24 h post-intervention) in the countermovement jump test with concentric (effect size (ES) = 0.36) and eccentric (ES = 0.26) velocity recovering more rapidly compared with the control. There were also small beneficial effects on 10- and 40-m sprint times. In the squat jump test there were delayed beneficial effects of occlusion on eccentric power (ES = 1.38), acceleration (ES = 1.24), and an immediate positive effect on jump height (ES = 0.61). Thus, specific beneficial effects on recovery of power production and sprint performance were observed both immediately and 24 h after intermittent unilateral occlusion was applied to each leg.


Cook C.J.,United Kingdom Sports Council | Cook C.J.,University of Bath | Cook C.J.,Imperial College London | Cook C.J.,University of Swansea | And 4 more authors.
American Journal of Human Biology | Year: 2012

Objectives: To compare the baseline free testosterone (T) and cortisol (C) concentrations of elite and non-elite female athletes. Methods: Eighteen females from different sports (track and field, netball, cycling, swimming, bob skeleton) were monitored over a 12-week period. Baseline measures of salivary free T and C concentrations were taken weekly prior to any training. The elites (n = 9) and non-elites (n = 9) were classified as international and national level competitors, respectively, with both groups matched by sport. Results: The pooled free T concentrations of the elites (87 pg/ml) were significantly higher than the non-elites (41 pg/ml) and consistently so across all weekly time points (P < 0.001). Pooled free C concentrations were also greater in the elite group (2.90 ng/ml) than the non-elites (2.32 ng/ml) (P < 0.01). Conclusions: The pooled baseline T and C measures were higher in elite female athletes than non-elites. Higher free T and C concentrations could indicate a greater capacity for physical performance at higher work rates, which is commensurate with the demands of elite sport. Speculatively, the T differences observed could influence female behavior and thereby help to regulate sporting potential. © 2012 Wiley Periodicals, Inc.


Cook C.J.,United Kingdom Sports Council | Kilduff L.P.,University of Swansea | Beaven C.M.,Mittuniversitetet
International Journal of Sports Physiology and Performance | Year: 2014

Purpose: To examine the effects of moderate-load exercise with and without blood-flow restriction (BFR) on strength, power, and repeated-sprint ability, along with acute and chronic salivary hormonal parameters. Methods: Twenty male semiprofessional rugby union athletes were randomized to a lower-body BFR intervention (an occlusion cuff inflated to 180 mmHg worn intermittently on the proximal thighs) or a control intervention that trained without occlusion in a crossover design. Experimental sessions were performed 3 times a week for 3 wk with 5 sets of 5 repetitions of bench press, leg squat, and pull-ups performed at 70% of 1-repetition maximum. Results: Greater improvements were observed (occlusion training vs control) in bench press (5.4 ± 2.6 vs 3.3 ± 1.4 kg), squat (7.8 ± 2.1 vs 4.3 ± 1.4 kg), maximum sprint time (-0.03 ± 0.03 vs -0.01 ± 0.02 s), and leg power (168 ± 105 vs 68 ± 50 W). Greater exercise-induced salivary testosterone (ES 0.84-0.61) and cortisol responses (ES 0.65-0.20) were observed after the occlusion intervention sessions compared with the nonoccluded controls; however, the acute cortisol increases were attenuated across the training block. Conclusions: Occlusion training can potentially improve the rate of strength-training gains and fatigue resistance in trained athletes, possibly allowing greater gains from lower loading that could be of benefit during high training loads, in competitive seasons, or in a rehabilitative setting. The clear improvement in bench-press strength resulting from lower-body occlusion suggests a systemic effect of BFR training. © 2014 Human Kinetics, Inc.


Cook C.,United Kingdom Sports Council | Beaven C.M.,National Winter Sports Research Center | Kilduff L.P.,University of Swansea | Drawer S.,United Kingdom Sports Council
International Journal of Sport Nutrition and Exercise Metabolism | Year: 2012

Introduction: This study aimed to determine whether caffeine ingestion would increase the workload voluntarily chosen by athletes in a limited-sleep state. Methods: In a double-blind, crossover study, 16 professional rugby players ingested either a placebo or 4 mg/kg caffeine 1 hr before exercise. Athletes classified themselves into nondeprived (8 hr+) or sleep-deprived states (6 hr or less). Exercise comprised 4 sets of bench press, squats, and bent rows at 85% 1-repetition maximum. Athletes were asked to perform as many repetitions on each set as possible without failure. Saliva was collected before administration of placebo or caffeine and again before and immediately after exercise and assayed for testosterone and cortisol. Results: Sleep deprivation produced a very large decrease in total load (p = 1.98 × 10-7). Caffeine ingestion in the nondeprived state resulted in a moderate increase in total load, with a larger effect in the sleep-deprived state, resulting in total load similar to those observed in the nondeprived placebo condition. Eight of the 16 athletes were identified as caffeine responders. Baseline testosterone was higher (p < .05) and cortisol trended lower in non-sleep-deprived athletes. Changes in hormones from predose to preexercise correlated to individual workload responses to caffeine. Testosterone response to exercise increased with caffeine compared with placebo, as did cortisol response. Conclusions: Caffeine increased voluntary workload in professional athletes, even more so under conditions of self-reported limited sleep. Caffeine may prove worthwhile when athletes are tired, especially in those identified as responders. © 2012 Human Kinetics, Inc.


Martyn Beaven C.,United Kingdom Sports Council | Martyn Beaven C.,Swedish Winter Sports Research Center | Cook C.,United Kingdom Sports Council | Gray D.,Hurricanes Rugby | And 6 more authors.
International Journal of Sports Physiology and Performance | Year: 2013

Rugby preseason training involves high-volume strength and conditioning training, necessitating effective management of the recovery-stress state to avoid overtraining and maximize adaptive gains. Purpose: Compression garments and an electrostimulation device have been proposed to improve recovery by increasing venous blood flow. These devices were assessed using salivary testosterone and cortisol, plasma creatine kinase, and player questionnaires to determine sleep quality, energy level, mood, and enthusiasm. Methods: Twenty-five professional rugby players were assigned to 1 of 2 treatments (compression garment or a concurrent combination of electrostimulation and compression) in a crossover design over 2 × 2-wk training blocks. Results: Substantial benefits were observed in self-assessed energy levels (effect size [ES] 0.86), and enthusiasm (ES 0.80) as a result of the combined treatment when compared with compression-garment use. The combination treatment had no discernable effect on salivary hormones, with no treatment effect observed. The electrostimulation device did tend to accelerate the return of creatine kinase to baseline levels after 2 preseason rugby games when compared with the compression-garment intervention (ES 0.61; P = .08). Conclusions: Electrostimulation elicited psychometric and physiological benefits reflective of an improved recovery-stress state in professional male rugby players when combined with a lower-body compression garment. © 2013 Human Kinetics, Inc.


Beaven C.M.,United Kingdom Sports Council | Beaven C.M.,Mid Sweden University | Maulder P.,Waikato Institute of Technology | Pooley A.,Waikato Institute of Technology | And 4 more authors.
Applied Physiology, Nutrition and Metabolism | Year: 2013

Our purpose was to examine the effectiveness of carbohydrate and caffeine mouth rinses in enhancing repeated sprint ability. Previously, studies have shown that a carbohydrate mouth rinse (without ingestion) has beneficial effects on endurance performance that are related to changes in brain activity. Caffeine ingestion has also demonstrated positive effects on sprint performance. However, the effects of carbohydrate or caffeine mouth rinses on intermittent sprints have not been examined previously. Twelve males performed 5 × 6-s sprints interspersed with 24 s of active recovery on a cycle ergometer. Twenty-five milliliters of either a noncaloric placebo, a 6% glucose, or a 1.2% caffeine solution was rinsed in the mouth for 5 s prior to each sprint in a double-blinded and balanced cross-over design. Postexercise maximal heart rate and perceived exertion were recorded, along with power measures. A second experiment compared a combined caffeine-carbohydrate rinse with carbohydrate only. Compared with the placebo mouth rinse, carbohydrate substantially increased peak power in sprint 1 (22.1 ± 19.5 W; Cohen's effect size (ES), 0.81), and both caffeine (26.9 ± 26.9 W; ES, 0.71) and carbohydrate (39.1 ± 25.8 W; ES, 1.08) improved mean power in sprint 1. Experiment 2 demonstrated that a combination of caffeine and carbohydrate improved sprint 1 power production compared with carbohydrate alone (36.0 ± 37.3 W; ES, 0.81). We conclude that carbohydrate and (or) caffeine mouth rinses may rapidly enhance power production, which could have benefits for specific short sprint exercise performance. The ability of a mouth-rinse intervention to rapidly improve maximal exercise performance in the absence of fatigue suggests a central mechanism.


Smith A.A.,University of Bath | Toone R.,University of Bath | Peacock O.,University of Bath | Drawer S.,United Kingdom Sports Council | And 2 more authors.
Journal of Applied Physiology | Year: 2013

Dihydrotestosterone (DHT) exerts both functional and signaling effects extending beyond the effects of testosterone in rodent skeletal muscle. As a primer for investigating the role of DHT in human skeletal muscle function, this study aimed to determine whether circulating DHT is acutely elevated in men following a bout of repeat sprint exercise and to establish the importance of training status and sprint performance to this response. Fourteen healthy active young men (V̇O2max 61.0 ± 8.1 ml·kg body mass-1·min-1) performed a bout of repeat sprint cycle exercise at a target workload based on an incremental work-rate maximum (10 × 30 s at 150% Wmax with 90-recovery). Venous blood samples were collected preexercise and 5 and 60 min after exercise. Five minutes after exercise, there were significant elevations in total testosterone (TT; P < 0.001), free testosterone (FT; P < 0.001), and DHT (P = 0.004), which returned to baseline after 1 h. Changes in DHT with exercise (5 min postexercise - preexercise) correlated significantly with changes in TT (r = 0.870; P < 0.001) and FT (r = 0.914; P < 0.001). Sprinting cadence correlated with changes in FT (r = 0.697; P = 0.006), DHT (r = 0.625; P = 0.017), and TT (r = 0.603; P = 0.022), and habitual training volume correlated with the change in TT (r = 0.569, P = 0.034). In conclusion, our data demonstrate that DHT is acutely elevated following sprint cycle exercise and that this response is influenced by cycling cadence. The importance of DHT in the context of exercise training and sports performance remains to be determined. Copyright © 2013 the American Physiological Society.


Cook C.J.,United Kingdom Sports Council | Cook C.J.,Imperial College London | Cook C.J.,University of Bath | Beaven C.M.,Mid Sweden University
British Journal of Sports Medicine | Year: 2013

Background: Training recovery is vital for adaptation and performance, and to avoid cumulative fatigue and symptoms associated with overtraining. The use of coldwater immersion (CWI) as a recovery strategy is common; however, the physiological and biochemical rationale behind its use remains unclear. This study aimed to assess the relationship between body temperature responses to water immersion and individual perception of recovery, with subsequent exercise performance. Methods: Twelve male rugby players participated in a 3- week cross-over trial where an intense 60 min conditioning session was followed immediately by 15 min of either 14°C CWI, 30°C warm-water immersion (WWI) or passive control (CON) recovery intervention. Postexercise body temperatures and subjective ratings of the recovery intervention were recorded and subsequently related to performance in a 5×40 m repeated sprint protocol undertaken 24 h later. Results: CWI induced large reductions in core body temperature postimmersion (effect size (ES) range 1.05- 3.21) and improved subsequent sprint performance compared to WWI (ES 1.04±0.84) and CON (ES 1.44 ±0.84). Both the degree of temperature decrease at 60 min postimmersion (r=0.6948; p=0.0121) and the subjective rating of the recovery intervention (r=0.5886; p=0.0441) were related to subsequent sprint performance. A very strong linear correlation was observed when these two factors were integrated (r=0.7743; p=0.0031). Conclusion A combination of physiological and psychological indices provides an improved indication of subsequent performance and suggests an important role of individual perception in enhancing training recovery.

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