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Heat acclimation responses of an ultra-endurance running group preparing for hot desert-based competition.
Eur J Sport Sci. 2014; 14 Suppl 1:S131-41.EJ

Abstract

Heat acclimation induces adaptations that improve exercise tolerance in hot conditions. Here we report novel findings into the effects of ultra-marathon specific exercise load in increasing hot ambient conditions on indices of heat acclimation. Six male ultra-endurance runners completed a standard pre-acclimation protocol at 20°C ambient temperature (T amb), followed by a heat acclimation protocol consisting of six 2 h running exercise-heat exposures (EH) at 60% VO2max on a motorised treadmill in an environmental chamber. Three EH were performed at 30°C T amb, followed by another three EH at 35°C T amb. EH were separated by 48 h within T amb and 72 h between T amb. Nude body mass (NBM), blood and urine samples were collected pre-exercise; while NBM and urine were collected post-exercise. Rectal temperature (T re), heart rate (HR), thermal comfort rating (TCR) and rating of perceived exertion were measured pre-exercise and monitored every 5 min during exercise. Water was provided ad libitum during exercise. Data were analysed using a repeated measures and one-way analysis of variance (ANOVA), with post hoc Tukey's HSD. Significance was accepted as P< 0.05. Overall mean T re was significantly lower during 30°C EH3 and 35°C EH3 compared with their respective EH1 (-0.20 and-0.23°C, respectively; P<0.05). Similarly, overall mean HR was significantly lower during 30°C EH3 and 35°C EH3 compared with their respective EH1 (8 and 7 bpm respectively; P<0.05). A significant decrease in overall mean TCR was observed during 35°C EH3, compared with 35°C EH1 (P< 0.05). Significant increases in resting pre-exercise plasma volume (estimated from Hb and Hct) were observed by 30°C EH3 (7.9%; P< 0.05). Thereafter, plasma volume remained above baseline throughout the experimental protocol. Two EH of 2 h at 60% VO2max at 30°C T amb was sufficient to initiate heat acclimation in all ultra-endurance runners. Further, heat acclimation responses occurred with increasing EH to 35°C T amb. Preventing exertional heat illnesses and optimising performance outcomes in ultra-endurance runners may occur with exposure to at least 2 h of exercise-heat stress on at least two occasions in the days leading up to multi-stage ultra-marathon competition in the heat.

Authors+Show Affiliations

a Department of Health Professions , Coventry University , Coventry , UK.No affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article

Language

eng

PubMed ID

24444197

Citation

Costa, Ricardo J S., et al. "Heat Acclimation Responses of an Ultra-endurance Running Group Preparing for Hot Desert-based Competition." European Journal of Sport Science, vol. 14 Suppl 1, 2014, pp. S131-41.
Costa RJ, Crockford MJ, Moore JP, et al. Heat acclimation responses of an ultra-endurance running group preparing for hot desert-based competition. Eur J Sport Sci. 2014;14 Suppl 1:S131-41.
Costa, R. J., Crockford, M. J., Moore, J. P., & Walsh, N. P. (2014). Heat acclimation responses of an ultra-endurance running group preparing for hot desert-based competition. European Journal of Sport Science, 14 Suppl 1, S131-41. https://doi.org/10.1080/17461391.2012.660506
Costa RJ, et al. Heat Acclimation Responses of an Ultra-endurance Running Group Preparing for Hot Desert-based Competition. Eur J Sport Sci. 2014;14 Suppl 1:S131-41. PubMed PMID: 24444197.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Heat acclimation responses of an ultra-endurance running group preparing for hot desert-based competition. AU - Costa,Ricardo J S, AU - Crockford,Michael J, AU - Moore,Jonathan P, AU - Walsh,Neil P, Y1 - 2012/03/19/ PY - 2014/1/22/entrez PY - 2014/1/22/pubmed PY - 2014/9/25/medline SP - S131 EP - 41 JF - European journal of sport science JO - Eur J Sport Sci VL - 14 Suppl 1 N2 - Heat acclimation induces adaptations that improve exercise tolerance in hot conditions. Here we report novel findings into the effects of ultra-marathon specific exercise load in increasing hot ambient conditions on indices of heat acclimation. Six male ultra-endurance runners completed a standard pre-acclimation protocol at 20°C ambient temperature (T amb), followed by a heat acclimation protocol consisting of six 2 h running exercise-heat exposures (EH) at 60% VO2max on a motorised treadmill in an environmental chamber. Three EH were performed at 30°C T amb, followed by another three EH at 35°C T amb. EH were separated by 48 h within T amb and 72 h between T amb. Nude body mass (NBM), blood and urine samples were collected pre-exercise; while NBM and urine were collected post-exercise. Rectal temperature (T re), heart rate (HR), thermal comfort rating (TCR) and rating of perceived exertion were measured pre-exercise and monitored every 5 min during exercise. Water was provided ad libitum during exercise. Data were analysed using a repeated measures and one-way analysis of variance (ANOVA), with post hoc Tukey's HSD. Significance was accepted as P< 0.05. Overall mean T re was significantly lower during 30°C EH3 and 35°C EH3 compared with their respective EH1 (-0.20 and-0.23°C, respectively; P<0.05). Similarly, overall mean HR was significantly lower during 30°C EH3 and 35°C EH3 compared with their respective EH1 (8 and 7 bpm respectively; P<0.05). A significant decrease in overall mean TCR was observed during 35°C EH3, compared with 35°C EH1 (P< 0.05). Significant increases in resting pre-exercise plasma volume (estimated from Hb and Hct) were observed by 30°C EH3 (7.9%; P< 0.05). Thereafter, plasma volume remained above baseline throughout the experimental protocol. Two EH of 2 h at 60% VO2max at 30°C T amb was sufficient to initiate heat acclimation in all ultra-endurance runners. Further, heat acclimation responses occurred with increasing EH to 35°C T amb. Preventing exertional heat illnesses and optimising performance outcomes in ultra-endurance runners may occur with exposure to at least 2 h of exercise-heat stress on at least two occasions in the days leading up to multi-stage ultra-marathon competition in the heat. SN - 1536-7290 UR - https://www.unboundmedicine.com/medline/citation/24444197/Heat_acclimation_responses_of_an_ultra_endurance_running_group_preparing_for_hot_desert_based_competition_ L2 - http://www.tandfonline.com/doi/full/10.1080/17461391.2012.660506 DB - PRIME DP - Unbound Medicine ER -