Impaired heat adaptation from combined heat training and "live high, train low" hypoxia

McCleave, EL; Slattery, KM; Duffield, R; Saunders, PU; Sharma, AP; Crowcroft, S; Coutts, AJ

Impaired heat adaptation from combined heat training and "live high, train low" hypoxia

McCleave, EL Slattery, KM Duffield, R

Saunders, PU Sharma, AP Crowcroft, S Coutts, AJ

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Publication Type:: Journal Article
Citation:: International Journal of Sports Physiology and Performance, 2019, 14 (5), pp. 635 - 643
Issue Date:: 2019-01-01

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Field	Value	Language
dc.contributor.author	McCleave, EL	en_US
dc.contributor.author	Slattery, KM	en_US
dc.contributor.author	Duffield, R https://orcid.org/0000-0002-5641-1314	en_US
dc.contributor.author	Saunders, PU	en_US
dc.contributor.author	Sharma, AP	en_US
dc.contributor.author	Crowcroft, S	en_US
dc.contributor.author	Coutts, AJ https://orcid.org/0000-0002-1782-7691	en_US
dc.date.issued	2019-01-01	en_US
dc.identifier.citation	International Journal of Sports Physiology and Performance, 2019, 14 (5), pp. 635 - 643	en_US
dc.identifier.issn	1555-0265	en_US
dc.identifier.uri	http://hdl.handle.net/10453/135467
dc.description.abstract	© 2019 Human Kinetics, Inc. Purpose: To determine whether combining training in heat with "Live High, Train Low" hypoxia (LHTL) further improves thermoregulatory and cardiovascular responses to a heat-tolerance test compared with independent heat training. Methods: A total of 25 trained runners (peak oxygen uptake = 64.1 [8.0] mL·min−1·kg−1) completed 3-wk training in 1 of 3 conditions: (1) heat training combined with "LHTL" hypoxia (H+H; FiO2 = 14.4% [3000 m], 13 h·d−1; train at <600 m, 33°C, 55% relative humidity [RH]), (2) heat training (HOT; live and train <600 m, 33°C, 55% RH), and (3) temperate training (CONT; live and train <600 m, 13°C, 55% RH). Heat adaptations were determined from a 45-min heat-response test (33°C, 55% RH, 65% velocity corresponding to the peak oxygen uptake) at baseline and immediately and 1 and 3 wk postexposure (baseline, post, 1 wkP, and 3 wkP, respectively). Core temperature, heart rate, sweat rate, sodium concentration, plasma volume, and perceptual responses were analyzed using magnitude-based inferences. Results: Submaximal heart rate (effect size [ES] = −0.60 [−0.89; −0.32]) and core temperature (ES = −0.55 [−0.99; −0.10]) were reduced in HOT until 1 wkP. Sweat rate (ES = 0.36 [0.12; 0.59]) and sweat sodium concentration (ES = −0.82 [−1.48; −0.16]) were, respectively, increased and decreased until 3 wkP in HOT. Submaximal heart rate (ES = −0.38 [−0.85; 0.08]) was likely reduced in H+H at 3 wkP, whereas CONT had unclear physiological changes. Perceived exertion and thermal sensation were reduced across all groups. Conclusions: Despite greater physiological stress from combined heat training and "LHTL" hypoxia, thermoregulatory adaptations are limited in comparison with independent heat training. The combined stimuli provide no additional physiological benefit during exercise in hot environments.	en_US
dc.relation.ispartof	International Journal of Sports Physiology and Performance	en_US
dc.relation.isbasedon	10.1123/ijspp.2018-0399	en_US
dc.rights	info:eu-repo/semantics/openAccess
dc.subject.classification	Sport Sciences	en_US
dc.subject.mesh	Acclimatization	en_US
dc.subject.mesh	Adult	en_US
dc.subject.mesh	Exercise Test	en_US
dc.subject.mesh	Female	en_US
dc.subject.mesh	Heart Rate	en_US
dc.subject.mesh	Hot Temperature	en_US
dc.subject.mesh	Humans	en_US
dc.subject.mesh	Hypoxia	en_US
dc.subject.mesh	Male	en_US
dc.subject.mesh	Plasma Volume	en_US
dc.subject.mesh	Running	en_US
dc.subject.mesh	Sweating	en_US
dc.subject.mesh	Thermotolerance	en_US
dc.subject.mesh	Young Adult	en_US
dc.title	Impaired heat adaptation from combined heat training and "live high, train low" hypoxia	en_US
dc.type	Journal Article
utslib.citation.volume	5	en_US
utslib.citation.volume	14	en_US
utslib.for	1106 Human Movement and Sports Sciences	en_US
utslib.for	1116 Medical Physiology	en_US
utslib.for	1701 Psychology	en_US
pubs.embargo.period	Not known	en_US
pubs.organisational-group	/University of Technology Sydney
pubs.organisational-group	/University of Technology Sydney/Faculty of Health
pubs.organisational-group	/University of Technology Sydney/Faculty of Health/Sports and Exercise Science
pubs.organisational-group	/University of Technology Sydney/Strength - CHSP - Health Services and Practice
pubs.organisational-group	/University of Technology Sydney/Strength - CHT - Health Technologies
pubs.organisational-group	/University of Technology Sydney/Students
utslib.copyright.status	open_access	*
pubs.issue	5	en_US
pubs.publication-status	Published	en_US
pubs.volume	14	en_US

Abstract:

© 2019 Human Kinetics, Inc. Purpose: To determine whether combining training in heat with "Live High, Train Low" hypoxia (LHTL) further improves thermoregulatory and cardiovascular responses to a heat-tolerance test compared with independent heat training. Methods: A total of 25 trained runners (peak oxygen uptake = 64.1 [8.0] mL·min−1·kg−1) completed 3-wk training in 1 of 3 conditions: (1) heat training combined with "LHTL" hypoxia (H+H; FiO2 = 14.4% [3000 m], 13 h·d−1; train at <600 m, 33°C, 55% relative humidity [RH]), (2) heat training (HOT; live and train <600 m, 33°C, 55% RH), and (3) temperate training (CONT; live and train <600 m, 13°C, 55% RH). Heat adaptations were determined from a 45-min heat-response test (33°C, 55% RH, 65% velocity corresponding to the peak oxygen uptake) at baseline and immediately and 1 and 3 wk postexposure (baseline, post, 1 wkP, and 3 wkP, respectively). Core temperature, heart rate, sweat rate, sodium concentration, plasma volume, and perceptual responses were analyzed using magnitude-based inferences. Results: Submaximal heart rate (effect size [ES] = −0.60 [−0.89; −0.32]) and core temperature (ES = −0.55 [−0.99; −0.10]) were reduced in HOT until 1 wkP. Sweat rate (ES = 0.36 [0.12; 0.59]) and sweat sodium concentration (ES = −0.82 [−1.48; −0.16]) were, respectively, increased and decreased until 3 wkP in HOT. Submaximal heart rate (ES = −0.38 [−0.85; 0.08]) was likely reduced in H+H at 3 wkP, whereas CONT had unclear physiological changes. Perceived exertion and thermal sensation were reduced across all groups. Conclusions: Despite greater physiological stress from combined heat training and "LHTL" hypoxia, thermoregulatory adaptations are limited in comparison with independent heat training. The combined stimuli provide no additional physiological benefit during exercise in hot environments.

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http://hdl.handle.net/10453/135467