title: 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.
abstract: 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.
authors.affiliation: Department of Sport, Exercise and Rehabilitation, Health and Life Sciences, Northumbria University, Newcastle upon Tyne, United Kingdom.
authors.forename: Mark
authors.initials: M
authors.lastname: Russell
authors.affiliation: Department of Sport, Exercise and Rehabilitation, Health and Life Sciences, Northumbria University, Newcastle upon Tyne, United Kingdom.
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: West
authors.affiliation: Department of Sport, Exercise and Rehabilitation, Health and Life Sciences, Northumbria University, Newcastle upon Tyne, United Kingdom.
authors.forename: Marc A
authors.initials: MA
authors.lastname: Briggs
authors.affiliation: Applied Sports Technology Exercise and Medicine Research Centre (A-STEM), Health and Sport Portfolio, Swansea University, Swansea, United Kingdom.
authors.forename: Richard M
authors.initials: RM
authors.lastname: Bracken
authors.affiliation: School of Sport, Health and Exercise Sciences, Bangor University, Bangor, United Kingdom.
authors.forename: Christian J
authors.initials: CJ
authors.lastname: Cook
authors.affiliation: Biarritz Olympique Rugby, Parc Des Sports Aguilera, Biarritz, France.
authors.forename: Thibault
authors.initials: T
authors.lastname: Giroud
authors.affiliation: Applied Sports Technology Exercise and Medicine Research Centre (A-STEM), Health and Sport Portfolio, Swansea University, Swansea, United Kingdom.
authors.forename: Nicholas
authors.initials: N
authors.lastname: Gill
authors.affiliation: Applied Sports Technology Exercise and Medicine Research Centre (A-STEM), Health and Sport Portfolio, Swansea University, Swansea, United Kingdom.
authors.forename: Liam P
authors.initials: LP
authors.lastname: Kilduff
mesh_terms: D015444:Exercise / Q000502:physiology*; D006358:Hot Temperature; D006801:Humans; D008297:Male; D053580:Muscle Strength / Q000502:physiology*; D013177:Sports / Q000502:physiology*; D055815:Young Adult