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Effects of hypohydration on thermoregulation during exercise before and after 5-day aerobic training in a warm environment in young men.
J Appl Physiol (1985). 2011 Apr; 110(4):972-80.JA

Abstract

We examined whether enhanced cardiovascular and thermoregulatory responses during exercise after short-term aerobic training in a warm environment were reversed when plasma volume (PV) expansion was reversed by acute isotonic hypohydration. Seven young men performed aerobic training at the 70% peak oxygen consumption rate (Vo(₂peak)) at 30°C atmospheric temperature and 50% relative humidity, 30 min/day for 5 days. Before and after training, we performed the thermoregulatory response test while measuring esophageal temperature (T(es)), forearm skin vascular conductance, sweat rate (SR), and PV during 30 min exercise at the metabolic rate equivalent to pretraining 65% Vo(₂peak) in euhydration under the same environment as during training in four trials (euhydration and hypohydration, respectively). Hypohydration targeting 3% body mass was attained by combined treatment with low-salt meals to subjects from ~48 h before the test and administration of a diuretic ~4 h before the test. After training, the T(es) thresholds for cutaneous vasodilation and sweating decreased by 0.3 and 0.2°C (P = 0.008 and 0.012, respectively) when PV increased by ~10%. When PV before and after training was reduced to a similar level, ~10% reduction from that in euhydration before training, the training-induced reduction in the threshold for cutaneous vasodilation increased to a level similar to hypohydration before training (P = 0.093) while that for sweating remained significantly lower than that before training (P = 0.004). Thus the enhanced cutaneous vasodilation response after aerobic training in a warm environment was reversed when PV expansion was reversed while the enhanced SR response remained partially.

Authors+Show Affiliations

Dept. of Sports Medical Sciences, Institute on Aging and Adaptation, Shinshu Univ. Graduate School of Medicine, Japan. nosehir@shinshu-u.ac.jpNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

21310891

Citation

Ikegawa, Shigeki, et al. "Effects of Hypohydration On Thermoregulation During Exercise Before and After 5-day Aerobic Training in a Warm Environment in Young Men." Journal of Applied Physiology (Bethesda, Md. : 1985), vol. 110, no. 4, 2011, pp. 972-80.
Ikegawa S, Kamijo Y, Okazaki K, et al. Effects of hypohydration on thermoregulation during exercise before and after 5-day aerobic training in a warm environment in young men. J Appl Physiol (1985). 2011;110(4):972-80.
Ikegawa, S., Kamijo, Y., Okazaki, K., Masuki, S., Okada, Y., & Nose, H. (2011). Effects of hypohydration on thermoregulation during exercise before and after 5-day aerobic training in a warm environment in young men. Journal of Applied Physiology (Bethesda, Md. : 1985), 110(4), 972-80. https://doi.org/10.1152/japplphysiol.01193.2010
Ikegawa S, et al. Effects of Hypohydration On Thermoregulation During Exercise Before and After 5-day Aerobic Training in a Warm Environment in Young Men. J Appl Physiol (1985). 2011;110(4):972-80. PubMed PMID: 21310891.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Effects of hypohydration on thermoregulation during exercise before and after 5-day aerobic training in a warm environment in young men. AU - Ikegawa,Shigeki, AU - Kamijo,Yoshi-Ichiro, AU - Okazaki,Kazunobu, AU - Masuki,Shizue, AU - Okada,Yoshiyuki, AU - Nose,Hiroshi, Y1 - 2011/02/10/ PY - 2011/2/12/entrez PY - 2011/2/12/pubmed PY - 2011/8/16/medline SP - 972 EP - 80 JF - Journal of applied physiology (Bethesda, Md. : 1985) JO - J Appl Physiol (1985) VL - 110 IS - 4 N2 - We examined whether enhanced cardiovascular and thermoregulatory responses during exercise after short-term aerobic training in a warm environment were reversed when plasma volume (PV) expansion was reversed by acute isotonic hypohydration. Seven young men performed aerobic training at the 70% peak oxygen consumption rate (Vo(₂peak)) at 30°C atmospheric temperature and 50% relative humidity, 30 min/day for 5 days. Before and after training, we performed the thermoregulatory response test while measuring esophageal temperature (T(es)), forearm skin vascular conductance, sweat rate (SR), and PV during 30 min exercise at the metabolic rate equivalent to pretraining 65% Vo(₂peak) in euhydration under the same environment as during training in four trials (euhydration and hypohydration, respectively). Hypohydration targeting 3% body mass was attained by combined treatment with low-salt meals to subjects from ~48 h before the test and administration of a diuretic ~4 h before the test. After training, the T(es) thresholds for cutaneous vasodilation and sweating decreased by 0.3 and 0.2°C (P = 0.008 and 0.012, respectively) when PV increased by ~10%. When PV before and after training was reduced to a similar level, ~10% reduction from that in euhydration before training, the training-induced reduction in the threshold for cutaneous vasodilation increased to a level similar to hypohydration before training (P = 0.093) while that for sweating remained significantly lower than that before training (P = 0.004). Thus the enhanced cutaneous vasodilation response after aerobic training in a warm environment was reversed when PV expansion was reversed while the enhanced SR response remained partially. SN - 1522-1601 UR - https://www.unboundmedicine.com/medline/citation/21310891/Effects_of_hypohydration_on_thermoregulation_during_exercise_before_and_after_5_day_aerobic_training_in_a_warm_environment_in_young_men_ L2 - https://journals.physiology.org/doi/10.1152/japplphysiol.01193.2010?url_ver=Z39.88-2003&rfr_id=ori:rid:crossref.org&rfr_dat=cr_pub=pubmed DB - PRIME DP - Unbound Medicine ER -