Tags

Type your tag names separated by a space and hit enter

Interactive effects of age and hydration state on human thermoregulatory function during exercise in hot-dry conditions.
Acta Physiol (Oxf) 2019; 226(1):e13226AP

Abstract

AIM

Ageing and hypohydration independently attenuate heat dissipation during exercise; however, the interactive effects of these factors remain unclear. We assessed the hypothesis that ageing suppresses hypohydration-induced reductions in whole-body heat loss during exercise in the heat.

METHODS

On two occasions, eight young (mean [SD]: 24 [4] years) and eight middle-aged (59 [5] years) men performed 30-minute bouts of light (heat production of 175 W m-2) and moderate (275 W m-2) cycling (separated by 15-minute rest) in the heat (40°C, 15% relative humidity) when euhydrated and hypohydrated (~4% reduction in body mass). Heat production and whole-body net heat exchange (evaporative heat loss + dry heat gain) were measured via indirect and direct calorimetry (respectively) and heat storage was calculated via their temporal summation.

RESULTS

Net heat exchange was reduced, while heat storage was elevated, in the middle-aged men during moderate exercise when euhydrated (both P ≤ 0.01). In the young, evaporative heat loss was attenuated in the hypohydrated vs euhydrated condition during light (199 ± 6 vs 211 ± 10 W m-2 ; P ≤ 0.01) and moderate (287 ± 15 vs 307 ± 13 W m-2 ; P ≤ 0.01) exercise, but was similar in the middle-aged men, averaging 223 ± 6 and 299 ± 15 W m-2 , respectively, across conditions (both P ≥ 0.32). Heat storage was thereby exacerbated by hypohydration in the young (both P < 0.01) but not the middle-aged (both P ≥ 0.32) during both exercise bouts and, as a result, was similar between groups when hypohydrated (both P ≥ 0.50).

CONCLUSION

Hypohydration attenuates heat loss via sweating in young but not middle-aged men, indicating that ageing impairs one's ability to mitigate further sweat-induced fluid loss during hypohydration.

Authors+Show Affiliations

Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Ontario, Canada.Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Ontario, Canada.Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Ontario, Canada.Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Ontario, Canada.Faculty of Physical Activity Sciences, University of Sherbrooke, Sherbrooke, Quebec, Canada.Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Ontario, Canada. Departments of Medicine, Cardiac Sciences and Community Health Sciences, Faculties of Medicine and Kinesiology, University of Calgary, Calgary, Alberta, Canada. Clinical Epidemiology Program, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada.Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Ontario, Canada. Clinical Epidemiology Program, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada.

Pub Type(s)

Journal Article

Language

eng

PubMed ID

30480873

Citation

Meade, Robert D., et al. "Interactive Effects of Age and Hydration State On Human Thermoregulatory Function During Exercise in Hot-dry Conditions." Acta Physiologica (Oxford, England), vol. 226, no. 1, 2019, pp. e13226.
Meade RD, Notley SR, D'Souza AW, et al. Interactive effects of age and hydration state on human thermoregulatory function during exercise in hot-dry conditions. Acta Physiol (Oxf). 2019;226(1):e13226.
Meade, R. D., Notley, S. R., D'Souza, A. W., Dervis, S., Boulay, P., Sigal, R. J., & Kenny, G. P. (2019). Interactive effects of age and hydration state on human thermoregulatory function during exercise in hot-dry conditions. Acta Physiologica (Oxford, England), 226(1), pp. e13226. doi:10.1111/apha.13226.
Meade RD, et al. Interactive Effects of Age and Hydration State On Human Thermoregulatory Function During Exercise in Hot-dry Conditions. Acta Physiol (Oxf). 2019;226(1):e13226. PubMed PMID: 30480873.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Interactive effects of age and hydration state on human thermoregulatory function during exercise in hot-dry conditions. AU - Meade,Robert D, AU - Notley,Sean R, AU - D'Souza,Andrew W, AU - Dervis,Sheila, AU - Boulay,Pierre, AU - Sigal,Ronald J, AU - Kenny,Glen P, Y1 - 2018/12/16/ PY - 2018/09/05/received PY - 2018/11/19/revised PY - 2018/11/22/accepted PY - 2018/11/28/pubmed PY - 2018/11/28/medline PY - 2018/11/28/entrez KW - ageing KW - dehydration KW - fluid regulation KW - heat stress KW - sweating KW - thermoregulation SP - e13226 EP - e13226 JF - Acta physiologica (Oxford, England) JO - Acta Physiol (Oxf) VL - 226 IS - 1 N2 - AIM: Ageing and hypohydration independently attenuate heat dissipation during exercise; however, the interactive effects of these factors remain unclear. We assessed the hypothesis that ageing suppresses hypohydration-induced reductions in whole-body heat loss during exercise in the heat. METHODS: On two occasions, eight young (mean [SD]: 24 [4] years) and eight middle-aged (59 [5] years) men performed 30-minute bouts of light (heat production of 175 W m-2) and moderate (275 W m-2) cycling (separated by 15-minute rest) in the heat (40°C, 15% relative humidity) when euhydrated and hypohydrated (~4% reduction in body mass). Heat production and whole-body net heat exchange (evaporative heat loss + dry heat gain) were measured via indirect and direct calorimetry (respectively) and heat storage was calculated via their temporal summation. RESULTS: Net heat exchange was reduced, while heat storage was elevated, in the middle-aged men during moderate exercise when euhydrated (both P ≤ 0.01). In the young, evaporative heat loss was attenuated in the hypohydrated vs euhydrated condition during light (199 ± 6 vs 211 ± 10 W m-2 ; P ≤ 0.01) and moderate (287 ± 15 vs 307 ± 13 W m-2 ; P ≤ 0.01) exercise, but was similar in the middle-aged men, averaging 223 ± 6 and 299 ± 15 W m-2 , respectively, across conditions (both P ≥ 0.32). Heat storage was thereby exacerbated by hypohydration in the young (both P < 0.01) but not the middle-aged (both P ≥ 0.32) during both exercise bouts and, as a result, was similar between groups when hypohydrated (both P ≥ 0.50). CONCLUSION: Hypohydration attenuates heat loss via sweating in young but not middle-aged men, indicating that ageing impairs one's ability to mitigate further sweat-induced fluid loss during hypohydration. SN - 1748-1716 UR - https://www.unboundmedicine.com/medline/citation/30480873/Interactive_effects_of_age_and_hydration_state_on_human_thermoregulatory_function_during_exercise_in_hot_dry_conditions_ L2 - https://doi.org/10.1111/apha.13226 DB - PRIME DP - Unbound Medicine ER -