title: Combined active and passive heat exposure induced heat acclimation in a soccer referee before 2014 FIFA World Cup.
abstract: BACKGROUND
  The 2014 FIFA World Cup was held in Brazil, where the climatic conditions presented a significant thermoregulatory and perceptual challenge to those unfamiliar with the heat and humidity.
  
  
  METHODS
  This case report documents the adaptation induced by a novel mixed methods (isothermic and passive) heat acclimation (HA) regime for a northern European professional soccer match official prior to the tournament. The intervention involved 13 HA sessions over an 18 day period comprising five isothermic HA sessions whereby intermittent running was used to target and maintain tympanic temperature (Tytemp) at 38 °C for 90 min, and seven passive HA sessions of 48 °C water bathing for 30 min. The athlete performed a heat stress test (HST) (35 min running at four incremental intensities in 30 °C) and a repeated high-intensity running test (as many 30 s self-paced efforts as possible, to a maximum of 20, with 30 s passive recovery) before and after the intervention. The mixed methods HA regime increased plasma volume (+7.1 %), and sweat loss (+0.9 L h(-1)), reduced exercising Tytemp (-0.6 °C), and mean body temperature (-0.5 °C). High-intensity running performance improved after HA (+29 %), as did the perception of thermal comfort during exercise (-0.3 units).
  
  
  CONCLUSIONS
  This data evidences the effectiveness of a practical, mixed methods HA strategy, remotely implemented around training and competition, at inducing the heat acclimation phenotype in a high-level soccer match official.
authors.affiliation: A016 Collegiate Hall, Centre for Sport and Exercise Science, Sheffield Hallam University, Sheffield, South Yorkshire S10 2BP UK.
authors.forename: A D
authors.initials: AD
authors.lastname: Ruddock
authors.affiliation: Academy of Sport and Physical Activity, A209 Collegiate Hall, Sheffield Hallam University, Collegiate Crescent Campus, Eccelsall Road, Sheffield, S10 2BP UK.
authors.forename: S W
authors.initials: SW
authors.lastname: Thompson
authors.affiliation: Department of Sport, Health and Nutrition, Leeds Trinity University, Brownberrie Lane, Horsforth, Leeds, LS18 5HD UK.
authors.forename: S A
authors.initials: SA
authors.lastname: Hudson
authors.affiliation: Environmental Extremes Laboratory, Centre for Sport and Exercise Science and Medicine (SESAME), University of Brighton, Welkin Laboratories, Denton Road, Eastbourne, East Sussex BN20 7SR UK.
authors.forename: C A
authors.initials: CA
authors.lastname: James
authors.affiliation: Centre for Sports Medicine and Human Performance (CSMHP), Heinz Wolff Building, Brunel University London, Uxbridge, UB8 3PH UK.
authors.forename: O R
authors.initials: OR
authors.lastname: Gibson
authors.affiliation: School of Sport and Health Sciences, George Building, Bangor University, Bangor, UK.
authors.forename: J A
authors.initials: JA
authors.lastname: Mee
keywords: Aerobic; Core temperature; Exercise; Hyperthermia; Interval training; Performance; Plasma volume; Thermoregulation