A comparison of different heat maintenance methods implemented during a simulated half-time period in professional Rugby Union players.

OBJECTIVES: In thermoneutral conditions, half-time is associated with reductions in body temperature that acutely impair performance. This laboratory-based study compared active, passive, and combined methods of half-time heat maintenance. DESIGN: Randomised, counterbalanced, cross-over. METHODS: After a standardised warm-up (WU) and 15min of rest, professional Rugby Union players (n=20) completed a repeated sprint test (RSSA1). Throughout a simulated half-time (temperature: 20.5±0.3°C; humidity: 53±5%), players then rested (Control) or wore a survival jacket (Passive) for 15min, or performed a 7min rewarm-up after either 8min of rest (Active), or 8min of wearing a survival jacket (Combined). A second RSSA (RSSA2) followed. Core temperature (Tcore) and peak power output (PPO; during countermovement jumps; CMJ) were measured at baseline, post-RSSA1, pre-RSSA2. RESULTS: All half-time interventions attenuated reductions in Tcore (0.62±0.28°C) observed in Control (Passive: -0.23±0.09°C; Active: -0.17±0.09°C; Combined: -0.03±0.10°C, all p<0.001) but Combined preserved Tcore the most (p<0.001). All half-time interventions attenuated the 385±137W reduction in Control PPO (Passive: -213±79W; Active: -83±72W; Combined: +10±52W; all p<0.001); with best PPO maintenance in Combined (p≤0.001). The fastest sprints occurred in RSSA2 in Combined (6.74±0.21s; p<0.001) but Passive (6.82±0.04s) and Active (6.80±0.05s) sprints were 0.4% (p=0.011) and 0.8% (p=0.002) quicker than Control (6.85±0.04s), respectively. CONCLUSIONS: While the efficacy of passive and active heat maintenance methods was supported throughout a simulated half-time, a combined approach to attenuating heat losses appeared the most beneficial for Tcore and subsequent PPO and sprint performance in professional Rugby Union players.

A Comparison of Different Modes of Morning Priming Exercise on Afternoon Performance.

PURPOSE: To assess the effects of different modes of morning (AM) exercise on afternoon (PM) performance and salivary hormone responses in professional rugby union players. METHODS: On 4 occasions (randomized, crossover design), 15 professional rugby players provided AM (~8 AM) and PM (~2 PM) saliva samples before PM assessments of countermovement-jump height, reaction time, and repeated-sprint ability. Control (passive rest), weights (bench press: 5 × 10 repetitions, 75% 1-repetition maximum, 90-s intraset recovery), cycling (6 × 6-s maximal sprint cycling, 7.5% body mass load, 54-s intraset recovery), and running (6 × 40-m maximal sprints, 20-s intraset recovery) interventions preceded (~5 h) PM testing. RESULTS: PM sprint performance improved (P < .05) after weights (>0.15 ± 0.19 s, >2.04% ± 2.46%) and running (>0.15 ± 0.17 s, >2.12% ± 2.22%) but not cycling (P > .05). PM jump height increased after cycling (0.012 ± 0.009 m, 2.31% ± 1.76%, P < .001) and running (0.020 ± 0.009 m, 3.90% ± 1.79%, P < .001) but not weights (P = .936). Reaction time remained unchanged between trials (P = .379). Relative to control (131 ± 21 pg/mL), PM testosterone was greater in weights (21 ± 23 pg/mL, 17% ± 18%, P = .002) and running (28 ± 26 pg/mL, 22% ± 20%, P = .001) but not cycling (P = .072). Salivary cortisol was unaffected by AM exercise (P = .540). CONCLUSIONS: All modes of AM exercise improved at least 1 marker of PM performance, but running appeared the most beneficial to professional rugby union players. A rationale therefore exists for preceding PM competition with AM exercise.

A passive heat maintenance strategy implemented during a simulated half-time improves lower body power output and repeated sprint ability in professional Rugby Union players.

Reduced physical performance has been observed following the half-time period in team sports players, likely due to a decrease in muscle temperature during this period. We examined the effects of a passive heat maintenance strategy employed between successive exercise bouts on core temperature (Tcore) and subsequent exercise performance. Eighteen professional Rugby Union players completed this randomised and counter-balanced study. After a standardised warm-up (WU) and 15 min of rest, players completed a repeated sprint test (RSSA 1) and countermovement jumps (CMJ). Thereafter, in normal training attire (Control) or a survival jacket (Passive), players rested for a further 15 min (simulating a typical half-time) before performing a second RSSA (RSSA 2) and CMJ's. Measurements of Tcore were taken at baseline, post-WU, pre-RSSA 1, post-RSSA 1 and pre-RSSA 2. Peak power output (PPO) and repeated sprint ability was assessed before and after the simulated half-time. Similar Tcore responses were observed between conditions at baseline (Control: 37.06±0.05°C; Passive: 37.03±0.05°C) and for all other Tcore measurements taken before half-time. After the simulated half-time, the decline in Tcore was lower (-0.74±0.08% vs. -1.54±0.06%, p<0.001) and PPO was higher (5610±105 W vs. 5440±105 W, p<0.001) in the Passive versus Control condition. The decline in PPO over half-time was related to the decline in Tcore (r = 0.632, p = 0.005). In RSSA 2, best, mean and total sprint times were 1.39±0.17% (p<0.001), 0.55±0.06% (p<0.001) and 0.55±0.06% (p<0.001) faster for Passive versus Control. Passive heat maintenance reduced declines in Tcore that were observed during a simulated half-time period and improved subsequent PPO and repeated sprint ability in professional Rugby Union players.