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Heat acclimation--mechanisms of adaptation to exercise in the heat.
Int J Sports Med. 1998 Jun; 19 Suppl 2:S154-6.IJ

Abstract

Repeated exposures to exercise and heat produce acclimatization, changes in physiological function by which the tolerance to heat stress is improved. The main issues to be discussed are the possible mechanisms for the increase in plasma volume, the increase in sweating rate and the endocrine responses to exercise with acclimation to both dry and humid heat. This will be discussed on the basis of the literature and our recent and ongoing experiments. We have tried to analyze this by comparing different acclimation procedures: exercise at 50-60% V/O2max, 60-90 min, dry heat 40 degrees C, 20% RH; 40-50% VO2max, 45-51 min, humid heat 35 degrees C, 85% RH; and 70-75% VO2max, 30-35 min, dry heat 40 degrees C, 20% RH. Subjects exercised in dry or humid heat for 8-12 consecutive days. Acclimation was achieved by all procedures, as indicated by a lower heart rate, increased plasma volume and sweating rate. We hypothesize that it is the repeated exposures to high core temperature that induce the changes, possibly via endocrine factors activated by the rising core temperature and the prolonged exercise. The increased sensitivity of the sweat glands for thermal and hormonal stimuli after acclimation may be obtained through an increase in receptor density for neural and humoral stimuli, an increase in the size, or, in number of active sweat glands.

Authors+Show Affiliations

August Krogh Institute, University of Copenhagen, Denmark.

Pub Type(s)

Comparative Study
Journal Article

Language

eng

PubMed ID

9694425

Citation

Nielsen, B. "Heat Acclimation--mechanisms of Adaptation to Exercise in the Heat." International Journal of Sports Medicine, vol. 19 Suppl 2, 1998, pp. S154-6.
Nielsen B. Heat acclimation--mechanisms of adaptation to exercise in the heat. Int J Sports Med. 1998;19 Suppl 2:S154-6.
Nielsen, B. (1998). Heat acclimation--mechanisms of adaptation to exercise in the heat. International Journal of Sports Medicine, 19 Suppl 2, S154-6.
Nielsen B. Heat Acclimation--mechanisms of Adaptation to Exercise in the Heat. Int J Sports Med. 1998;19 Suppl 2:S154-6. PubMed PMID: 9694425.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Heat acclimation--mechanisms of adaptation to exercise in the heat. A1 - Nielsen,B, PY - 1998/8/7/pubmed PY - 1998/8/7/medline PY - 1998/8/7/entrez SP - S154 EP - 6 JF - International journal of sports medicine JO - Int J Sports Med VL - 19 Suppl 2 N2 - Repeated exposures to exercise and heat produce acclimatization, changes in physiological function by which the tolerance to heat stress is improved. The main issues to be discussed are the possible mechanisms for the increase in plasma volume, the increase in sweating rate and the endocrine responses to exercise with acclimation to both dry and humid heat. This will be discussed on the basis of the literature and our recent and ongoing experiments. We have tried to analyze this by comparing different acclimation procedures: exercise at 50-60% V/O2max, 60-90 min, dry heat 40 degrees C, 20% RH; 40-50% VO2max, 45-51 min, humid heat 35 degrees C, 85% RH; and 70-75% VO2max, 30-35 min, dry heat 40 degrees C, 20% RH. Subjects exercised in dry or humid heat for 8-12 consecutive days. Acclimation was achieved by all procedures, as indicated by a lower heart rate, increased plasma volume and sweating rate. We hypothesize that it is the repeated exposures to high core temperature that induce the changes, possibly via endocrine factors activated by the rising core temperature and the prolonged exercise. The increased sensitivity of the sweat glands for thermal and hormonal stimuli after acclimation may be obtained through an increase in receptor density for neural and humoral stimuli, an increase in the size, or, in number of active sweat glands. SN - 0172-4622 UR - https://www.unboundmedicine.com/medline/citation/9694425/Heat_acclimation__mechanisms_of_adaptation_to_exercise_in_the_heat_ L2 - http://www.thieme-connect.com/DOI/DOI?10.1055/s-2007-971984 DB - PRIME DP - Unbound Medicine ER -