title: Short-term heat acclimation prior to a multi-day desert ultra-marathon improves physiological and psychological responses without compromising immune status.
abstract: Multistage, ultra-endurance events in hot, humid conditions necessitate thermal adaptation, often achieved through short term heat acclimation (STHA), to improve performance by reducing thermoregulatory strain and perceptions of heat stress. This study investigated the physiological, perceptual and immunological responses to STHA prior to the Marathon des Sables. Eight athletes (age 42 ± 4 years and body mass 81.9 ± 15.0 kg) completed 4 days of controlled hyperthermia STHA (60 min·day‒1, 45°C and 30% relative humidity). Pre, during and post sessions, physiological and perceptual measures were recorded. Immunological measures were recorded pre-post sessions 1 and 4. STHA improved thermal comfort (P = 0.02), sensation (P = 0.03) and perceived exertion (P = 0.04). A dissociated relationship between perceptual fatigue and Trewas evident after STHA, with reductions in perceived Physical (P = 0.04) and General (P = 0.04) fatigue. Exercising Treand HR did not change (P > 0.05) however, sweat rate increased 14% (P = 0.02). No changes were found in white blood cell counts or content (P > 0.05). Four days of STHA facilitates effective perceptual adaptations, without compromising immune status prior to an ultra-endurance race in heat stress. A greater physiological strain is required to confer optimal physiological adaptations.
authors.affiliation: a Environmental Extremes Laboratory, Centre for Sport and Exercise Science and Medicine (SESAME), Sport and Exercise Science Consultancy Unit (SESCU) , University of Brighton , Eastbourne , UK.
authors.forename: Ashley G B
authors.initials: AGB
authors.lastname: Willmott
authors.affiliation: a Environmental Extremes Laboratory, Centre for Sport and Exercise Science and Medicine (SESAME), Sport and Exercise Science Consultancy Unit (SESCU) , University of Brighton , Eastbourne , UK.
authors.forename: Mark
authors.initials: M
authors.lastname: Hayes
authors.affiliation: a Environmental Extremes Laboratory, Centre for Sport and Exercise Science and Medicine (SESAME), Sport and Exercise Science Consultancy Unit (SESCU) , University of Brighton , Eastbourne , UK.
authors.forename: Kirsty A M
authors.initials: KAM
authors.lastname: Waldock
authors.affiliation: a Environmental Extremes Laboratory, Centre for Sport and Exercise Science and Medicine (SESAME), Sport and Exercise Science Consultancy Unit (SESCU) , University of Brighton , Eastbourne , UK.
authors.forename: Rebecca L
authors.initials: RL
authors.lastname: Relf
authors.affiliation: a Environmental Extremes Laboratory, Centre for Sport and Exercise Science and Medicine (SESAME), Sport and Exercise Science Consultancy Unit (SESCU) , University of Brighton , Eastbourne , UK.
authors.forename: Emily R
authors.initials: ER
authors.lastname: Watkins
authors.affiliation: b National Sports Institute (Institut Sukan Negara) , National Sport Complex , Kuala Lumpur , Malaysia.
authors.forename: Carl A
authors.initials: CA
authors.lastname: James
authors.affiliation: c Centre for Human Performance, Exercise and Rehabilitation , Brunel University London , London , UK.
authors.forename: Oliver R
authors.initials: OR
authors.lastname: Gibson
authors.affiliation: a Environmental Extremes Laboratory, Centre for Sport and Exercise Science and Medicine (SESAME), Sport and Exercise Science Consultancy Unit (SESCU) , University of Brighton , Eastbourne , UK.
authors.forename: Nicholas J
authors.initials: NJ
authors.lastname: Smeeton
authors.affiliation: a Environmental Extremes Laboratory, Centre for Sport and Exercise Science and Medicine (SESAME), Sport and Exercise Science Consultancy Unit (SESCU) , University of Brighton , Eastbourne , UK.
authors.forename: Alan J
authors.initials: AJ
authors.lastname: Richardson
authors.affiliation: a Environmental Extremes Laboratory, Centre for Sport and Exercise Science and Medicine (SESAME), Sport and Exercise Science Consultancy Unit (SESCU) , University of Brighton , Eastbourne , UK.
authors.forename: Peter W
authors.initials: PW
authors.lastname: Watt
authors.affiliation: a Environmental Extremes Laboratory, Centre for Sport and Exercise Science and Medicine (SESAME), Sport and Exercise Science Consultancy Unit (SESCU) , University of Brighton , Eastbourne , UK.
authors.forename: Neil S
authors.initials: NS
authors.lastname: Maxwell
mesh_terms: D000064:Acclimatization / Q000276:immunology / Q000502:physiology; D000328:Adult; D056352:Athletes; D003889:Desert Climate; D006358:Hot Temperature; D006801:Humans; D008297:Male; D012420:Running / Q000502:physiology*; D013546:Sweating
keywords: Short-term heat acclimation; heat stress; perceived fatigue; thermoregulation; ultra-endurance