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Heat Acclimation in Females Does Not Limit Aerobic Exercise Training Outcomes

Recent aerobic exercise training in the heat has reported blunted aerobic power improvements and reduced mitochondrial-related gene expression in men. It is unclear if this heat-induced blunting of the training response exists in females. The purpose of the present study was to determine the impact...

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Autores principales: McGlynn, Mark L., Collins, Christopher, Hailes, Walter, Ruby, Brent, Slivka, Dustin
Formato: Online Artículo Texto
Lenguaje:English
Publicado: MDPI 2022
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9103535/
https://www.ncbi.nlm.nih.gov/pubmed/35564948
http://dx.doi.org/10.3390/ijerph19095554
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author McGlynn, Mark L.
Collins, Christopher
Hailes, Walter
Ruby, Brent
Slivka, Dustin
author_facet McGlynn, Mark L.
Collins, Christopher
Hailes, Walter
Ruby, Brent
Slivka, Dustin
author_sort McGlynn, Mark L.
collection PubMed
description Recent aerobic exercise training in the heat has reported blunted aerobic power improvements and reduced mitochondrial-related gene expression in men. It is unclear if this heat-induced blunting of the training response exists in females. The purpose of the present study was to determine the impact of 60 min of cycling in the heat over three weeks on thermoregulation, gene expression, and aerobic capacity in females. Untrained females (n = 22; 24 ± 4yoa) were assigned to three weeks of aerobic training in either 20 °C (n = 12) or 33 °C (n = 10; 40%RH). Maximal aerobic capacity (39.5 ± 6.5 to 41.5 ± 6.2 mL·kg(−1)·min(−1), p = 0.021, η(p)(2) = 0.240, 95% CI [0.315, 3.388]) and peak aerobic power (191.0 ± 33.0 to 206.7 ± 27.2 W, p < 0.001, η(p)(2) = 0.531, 95% CI [8.734, 22.383]) increased, while the absolute-intensity trial (50%VO(2peak)) HR decreased (152 ± 15 to 140 ± 13 b·min(−1), p < 0.001, η(p)(2) = 0.691, 95% CI [15.925, 8.353]), but they were not different between temperatures (p = 0.440, p = 0.955, p = 0.341, respectively). Independent of temperature, Day 22 tolerance trial skin temperatures decreased from Day 1 (p = 0.006, η(p)(2) = 0.319, 95% CI [1.408, 0.266), but training did not influence core temperature (p = 0.598). Average sweat rates were higher in the 33 °C group vs. the 20 °C group (p = 0.008, η(p)(2) = 0.303, 95% CI [67.9, 394.9]) but did not change due to training (p = 0.571). Pre-training PGC-1α mRNA increased 4h-post-exercise (5.29 ± 0.70 fold change, p < 0.001), was lower post-training (2.69 ± 0.22 fold change, p = 0.004), and was not different between temperatures (p = 0.455). While training induced some diminished transcriptional stimulus, generally the training temperature had little effect on genes related to mitochondrial biogenesis, mitophagy, and metabolic enzymes. These female participants increased aerobic fitness and maintained an exercise-induced PGC-1α mRNA response in the heat equal to that of room temperature conditions, contrasting with the blunted responses previously observed in men.
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spelling pubmed-91035352022-05-14 Heat Acclimation in Females Does Not Limit Aerobic Exercise Training Outcomes McGlynn, Mark L. Collins, Christopher Hailes, Walter Ruby, Brent Slivka, Dustin Int J Environ Res Public Health Article Recent aerobic exercise training in the heat has reported blunted aerobic power improvements and reduced mitochondrial-related gene expression in men. It is unclear if this heat-induced blunting of the training response exists in females. The purpose of the present study was to determine the impact of 60 min of cycling in the heat over three weeks on thermoregulation, gene expression, and aerobic capacity in females. Untrained females (n = 22; 24 ± 4yoa) were assigned to three weeks of aerobic training in either 20 °C (n = 12) or 33 °C (n = 10; 40%RH). Maximal aerobic capacity (39.5 ± 6.5 to 41.5 ± 6.2 mL·kg(−1)·min(−1), p = 0.021, η(p)(2) = 0.240, 95% CI [0.315, 3.388]) and peak aerobic power (191.0 ± 33.0 to 206.7 ± 27.2 W, p < 0.001, η(p)(2) = 0.531, 95% CI [8.734, 22.383]) increased, while the absolute-intensity trial (50%VO(2peak)) HR decreased (152 ± 15 to 140 ± 13 b·min(−1), p < 0.001, η(p)(2) = 0.691, 95% CI [15.925, 8.353]), but they were not different between temperatures (p = 0.440, p = 0.955, p = 0.341, respectively). Independent of temperature, Day 22 tolerance trial skin temperatures decreased from Day 1 (p = 0.006, η(p)(2) = 0.319, 95% CI [1.408, 0.266), but training did not influence core temperature (p = 0.598). Average sweat rates were higher in the 33 °C group vs. the 20 °C group (p = 0.008, η(p)(2) = 0.303, 95% CI [67.9, 394.9]) but did not change due to training (p = 0.571). Pre-training PGC-1α mRNA increased 4h-post-exercise (5.29 ± 0.70 fold change, p < 0.001), was lower post-training (2.69 ± 0.22 fold change, p = 0.004), and was not different between temperatures (p = 0.455). While training induced some diminished transcriptional stimulus, generally the training temperature had little effect on genes related to mitochondrial biogenesis, mitophagy, and metabolic enzymes. These female participants increased aerobic fitness and maintained an exercise-induced PGC-1α mRNA response in the heat equal to that of room temperature conditions, contrasting with the blunted responses previously observed in men. MDPI 2022-05-03 /pmc/articles/PMC9103535/ /pubmed/35564948 http://dx.doi.org/10.3390/ijerph19095554 Text en © 2022 by the authors. https://creativecommons.org/licenses/by/4.0/Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).
spellingShingle Article
McGlynn, Mark L.
Collins, Christopher
Hailes, Walter
Ruby, Brent
Slivka, Dustin
Heat Acclimation in Females Does Not Limit Aerobic Exercise Training Outcomes
title Heat Acclimation in Females Does Not Limit Aerobic Exercise Training Outcomes
title_full Heat Acclimation in Females Does Not Limit Aerobic Exercise Training Outcomes
title_fullStr Heat Acclimation in Females Does Not Limit Aerobic Exercise Training Outcomes
title_full_unstemmed Heat Acclimation in Females Does Not Limit Aerobic Exercise Training Outcomes
title_short Heat Acclimation in Females Does Not Limit Aerobic Exercise Training Outcomes
title_sort heat acclimation in females does not limit aerobic exercise training outcomes
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9103535/
https://www.ncbi.nlm.nih.gov/pubmed/35564948
http://dx.doi.org/10.3390/ijerph19095554
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