Tags

Type your tag names separated by a space and hit enter

Thermoregulatory and blood responses during exercise at graded hypohydration levels.
J Appl Physiol (1985). 1985 Nov; 59(5):1394-401.JA

Abstract

We studied the effects of graded hypohydration levels on thermoregulatory and blood responses during exercise in the heat. Eight heat-acclimated male subjects attempted four heat-stress tests (HSTs). One HST was attempted during euhydration, and three HSTs were attempted while the subjects were hypohydrated by 3, 5, and 7% of their body weight. Hypohydration was achieved by an exercise-heat regimen on the day prior to each HST. After 30 min of rest in a 20 degrees C antechamber the HST consisted of a 140-min exposure (4 repeats of 10 min rest and 25 min treadmill walking) in a hot-dry (49 degrees C, 20% relative humidity) environment. The following observations were made: 1) a low-to-moderate hypohydration level primarily reduced plasma volume with little effect on plasma osmolality, whereas a more severe hypohydration level resulted in no further plasma volume reduction but a large increment in plasma osmolality; 2) core temperature and heart rate responses increased with severity of hypohydration; 3) sweating rate responses for a given rectal temperature were systematically decreased with severity of hypohydration; and 4) the reduction in sweating rate was more strongly associated with plasma hyperosmolality than hypovolemia. In conclusion, an individual's thermal strain increases linearly with the severity of hypohydration during exercise in the heat, and plasma hyperosmolality influences the reduction in sweating more profoundly than hypovolemia.

Authors

No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Comparative Study
Journal Article

Language

eng

PubMed ID

4066570

Citation

Sawka, M N., et al. "Thermoregulatory and Blood Responses During Exercise at Graded Hypohydration Levels." Journal of Applied Physiology (Bethesda, Md. : 1985), vol. 59, no. 5, 1985, pp. 1394-401.
Sawka MN, Young AJ, Francesconi RP, et al. Thermoregulatory and blood responses during exercise at graded hypohydration levels. J Appl Physiol (1985). 1985;59(5):1394-401.
Sawka, M. N., Young, A. J., Francesconi, R. P., Muza, S. R., & Pandolf, K. B. (1985). Thermoregulatory and blood responses during exercise at graded hypohydration levels. Journal of Applied Physiology (Bethesda, Md. : 1985), 59(5), 1394-401.
Sawka MN, et al. Thermoregulatory and Blood Responses During Exercise at Graded Hypohydration Levels. J Appl Physiol (1985). 1985;59(5):1394-401. PubMed PMID: 4066570.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Thermoregulatory and blood responses during exercise at graded hypohydration levels. AU - Sawka,M N, AU - Young,A J, AU - Francesconi,R P, AU - Muza,S R, AU - Pandolf,K B, PY - 1985/11/1/pubmed PY - 1985/11/1/medline PY - 1985/11/1/entrez SP - 1394 EP - 401 JF - Journal of applied physiology (Bethesda, Md. : 1985) JO - J Appl Physiol (1985) VL - 59 IS - 5 N2 - We studied the effects of graded hypohydration levels on thermoregulatory and blood responses during exercise in the heat. Eight heat-acclimated male subjects attempted four heat-stress tests (HSTs). One HST was attempted during euhydration, and three HSTs were attempted while the subjects were hypohydrated by 3, 5, and 7% of their body weight. Hypohydration was achieved by an exercise-heat regimen on the day prior to each HST. After 30 min of rest in a 20 degrees C antechamber the HST consisted of a 140-min exposure (4 repeats of 10 min rest and 25 min treadmill walking) in a hot-dry (49 degrees C, 20% relative humidity) environment. The following observations were made: 1) a low-to-moderate hypohydration level primarily reduced plasma volume with little effect on plasma osmolality, whereas a more severe hypohydration level resulted in no further plasma volume reduction but a large increment in plasma osmolality; 2) core temperature and heart rate responses increased with severity of hypohydration; 3) sweating rate responses for a given rectal temperature were systematically decreased with severity of hypohydration; and 4) the reduction in sweating rate was more strongly associated with plasma hyperosmolality than hypovolemia. In conclusion, an individual's thermal strain increases linearly with the severity of hypohydration during exercise in the heat, and plasma hyperosmolality influences the reduction in sweating more profoundly than hypovolemia. SN - 8750-7587 UR - https://www.unboundmedicine.com/medline/citation/4066570/Thermoregulatory_and_blood_responses_during_exercise_at_graded_hypohydration_levels_ L2 - https://journals.physiology.org/doi/10.1152/jappl.1985.59.5.1394?url_ver=Z39.88-2003&rfr_id=ori:rid:crossref.org&rfr_dat=cr_pub=pubmed DB - PRIME DP - Unbound Medicine ER -