Tags

Type your tag names separated by a space and hit enter

Effect of an exercise-heat acclimation program on body fluid regulatory responses to dehydration in older men.
Am J Physiol. 1999 10; 277(4):R1041-50.AJ

Abstract

We examined if an exercise-heat acclimation program improves body fluid regulatory function in older subjects, as has been reported in younger subjects. Nine older (Old; 70 +/- 3 yr) and six younger (Young; 25 +/- 3 yr) male subjects participated in the study. Body fluid regulatory responses to an acute thermal dehydration challenge were examined before and after the 6-day acclimation session. Acute dehydration was produced by intermittent light exercise [4 bouts of 20-min exercise at 40% peak rate of oxygen consumption (VO(2 peak)) separated by 10 min rest] in the heat (36 degrees C; 40% relative humidity) followed by 30 min of recovery without fluid intake at 25 degrees C. During the 2-h rehydration period the subjects drank a carbohydrate-electrolyte solution ad libitum. In the preacclimation test, the Old lost approximately 0.8 kg during dehydration and recovered 31 +/- 4% of that loss during rehydration, whereas the Young lost approximately 1.2 kg and recovered 56 +/- 8% (P < 0.05, Young vs. Old). During the 6-day heat acclimation period all subjects performed the same exercise-heat exposure as in the dehydration period. Exercise-heat acclimation increased plasma volume by approximately 5% (P < 0.05) in Young subjects but not in Old. The body fluid loss during dehydration in the postacclimation test was similar to that in the preacclimation in Young and Old. The fractional recovery of lost fluid volume during rehydration increased in Young (by 80 +/- 9%; P < 0.05) but not in Old (by only 34 +/- 5%; NS). The improved recovery from dehydration in Young was mainly due to increased fluid intake with a small increase in the fluid retention fraction. The greater involuntary dehydration (greater fluid deficit) in Old was accompanied by reduced plasma vasopressin and aldosterone concentrations, renin activity, and subjective thirst rating (P < 0.05, Young vs. Old). Thus older people have reduced ability to facilitate body fluid regulatory function by exercise-heat acclimation, which might be involved in attenuation of the acclimation-induced increase in body fluid volume.

Authors+Show Affiliations

Department of Physiology, Kyoto Prefectural University of Medicine, Kyoto 602-0841, Japan. akira@phys.kpu-m.ac.jpNo affiliation info availableNo affiliation info availableNo 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

10516243

Citation

Takamata, A, et al. "Effect of an Exercise-heat Acclimation Program On Body Fluid Regulatory Responses to Dehydration in Older Men." The American Journal of Physiology, vol. 277, no. 4, 1999, pp. R1041-50.
Takamata A, Ito T, Yaegashi K, et al. Effect of an exercise-heat acclimation program on body fluid regulatory responses to dehydration in older men. Am J Physiol. 1999;277(4):R1041-50.
Takamata, A., Ito, T., Yaegashi, K., Takamiya, H., Maegawa, Y., Itoh, T., Greenleaf, J. E., & Morimoto, T. (1999). Effect of an exercise-heat acclimation program on body fluid regulatory responses to dehydration in older men. The American Journal of Physiology, 277(4), R1041-50. https://doi.org/10.1152/ajpregu.1999.277.4.R1041
Takamata A, et al. Effect of an Exercise-heat Acclimation Program On Body Fluid Regulatory Responses to Dehydration in Older Men. Am J Physiol. 1999;277(4):R1041-50. PubMed PMID: 10516243.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Effect of an exercise-heat acclimation program on body fluid regulatory responses to dehydration in older men. AU - Takamata,A, AU - Ito,T, AU - Yaegashi,K, AU - Takamiya,H, AU - Maegawa,Y, AU - Itoh,T, AU - Greenleaf,J E, AU - Morimoto,T, PY - 1999/10/12/pubmed PY - 1999/10/12/medline PY - 1999/10/12/entrez KW - Non-programmatic SP - R1041 EP - 50 JF - The American journal of physiology JO - Am. J. Physiol. VL - 277 IS - 4 N2 - We examined if an exercise-heat acclimation program improves body fluid regulatory function in older subjects, as has been reported in younger subjects. Nine older (Old; 70 +/- 3 yr) and six younger (Young; 25 +/- 3 yr) male subjects participated in the study. Body fluid regulatory responses to an acute thermal dehydration challenge were examined before and after the 6-day acclimation session. Acute dehydration was produced by intermittent light exercise [4 bouts of 20-min exercise at 40% peak rate of oxygen consumption (VO(2 peak)) separated by 10 min rest] in the heat (36 degrees C; 40% relative humidity) followed by 30 min of recovery without fluid intake at 25 degrees C. During the 2-h rehydration period the subjects drank a carbohydrate-electrolyte solution ad libitum. In the preacclimation test, the Old lost approximately 0.8 kg during dehydration and recovered 31 +/- 4% of that loss during rehydration, whereas the Young lost approximately 1.2 kg and recovered 56 +/- 8% (P < 0.05, Young vs. Old). During the 6-day heat acclimation period all subjects performed the same exercise-heat exposure as in the dehydration period. Exercise-heat acclimation increased plasma volume by approximately 5% (P < 0.05) in Young subjects but not in Old. The body fluid loss during dehydration in the postacclimation test was similar to that in the preacclimation in Young and Old. The fractional recovery of lost fluid volume during rehydration increased in Young (by 80 +/- 9%; P < 0.05) but not in Old (by only 34 +/- 5%; NS). The improved recovery from dehydration in Young was mainly due to increased fluid intake with a small increase in the fluid retention fraction. The greater involuntary dehydration (greater fluid deficit) in Old was accompanied by reduced plasma vasopressin and aldosterone concentrations, renin activity, and subjective thirst rating (P < 0.05, Young vs. Old). Thus older people have reduced ability to facilitate body fluid regulatory function by exercise-heat acclimation, which might be involved in attenuation of the acclimation-induced increase in body fluid volume. SN - 0002-9513 UR - https://www.unboundmedicine.com/medline/citation/10516243/Effect_of_an_exercise_heat_acclimation_program_on_body_fluid_regulatory_responses_to_dehydration_in_older_men_ L2 - http://journals.physiology.org/doi/full/10.1152/ajpregu.1999.277.4.R1041?url_ver=Z39.88-2003&amp;rfr_id=ori:rid:crossref.org&amp;rfr_dat=cr_pub=pubmed DB - PRIME DP - Unbound Medicine ER -