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

Erin L. McCleave, Katie M. Slattery, Rob Duffield, Philo U. Saunders, Avish P. Sharma, Stephen Crowcroft, Aaron J. Coutts

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

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.

Original languageEnglish
Pages (from-to)635-643
Number of pages9
JournalInternational Journal of Sports Physiology and Performance
Volume14
Issue number5
DOIs
Publication statusPublished - 2019

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Hot Temperature
Humidity
Sweat
Heart Rate
Sodium
Oxygen
Physiological Stress
Temperature
Hypesthesia
Hypoxia
Thermotolerance
Plasma Volume

Cite this

McCleave, E. L., Slattery, K. M., Duffield, R., Saunders, P. U., Sharma, A. P., Crowcroft, S., & Coutts, A. J. (2019). Impaired heat adaptation from combined heat training and "live high, train low" hypoxia. International Journal of Sports Physiology and Performance, 14(5), 635-643. https://doi.org/10.1123/ijspp.2018-0399
McCleave, Erin L. ; Slattery, Katie M. ; Duffield, Rob ; Saunders, Philo U. ; Sharma, Avish P. ; Crowcroft, Stephen ; Coutts, Aaron J. / Impaired heat adaptation from combined heat training and "live high, train low" hypoxia. In: International Journal of Sports Physiology and Performance. 2019 ; Vol. 14, No. 5. pp. 635-643.
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abstract = "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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McCleave, EL, Slattery, KM, Duffield, R, Saunders, PU, Sharma, AP, Crowcroft, S & Coutts, AJ 2019, 'Impaired heat adaptation from combined heat training and "live high, train low" hypoxia', International Journal of Sports Physiology and Performance, vol. 14, no. 5, pp. 635-643. https://doi.org/10.1123/ijspp.2018-0399

Impaired heat adaptation from combined heat training and "live high, train low" hypoxia. / McCleave, Erin L.; Slattery, Katie M.; Duffield, Rob; Saunders, Philo U.; Sharma, Avish P.; Crowcroft, Stephen; Coutts, Aaron J.

In: International Journal of Sports Physiology and Performance, Vol. 14, No. 5, 2019, p. 635-643.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Impaired heat adaptation from combined heat training and "live high, train low" hypoxia

AU - McCleave, Erin L.

AU - Slattery, Katie M.

AU - Duffield, Rob

AU - Saunders, Philo U.

AU - Sharma, Avish P.

AU - Crowcroft, Stephen

AU - Coutts, Aaron J.

PY - 2019

Y1 - 2019

N2 - 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.

AB - 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.

KW - Acclimation

KW - Altitude

KW - Cross-tolerance

KW - Endurance

KW - Environment

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U2 - 10.1123/ijspp.2018-0399

DO - 10.1123/ijspp.2018-0399

M3 - Article

VL - 14

SP - 635

EP - 643

JO - International Journal of Sports Physiology and Performance

JF - International Journal of Sports Physiology and Performance

SN - 1555-0265

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ER -