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Plasma hormonal responses at graded hypohydration levels during exercise-heat stress.
J Appl Physiol (1985). 1985 Dec; 59(6):1855-60.JA

Abstract

The effects of graded levels of hypohydration (3, 5, and 7% of body weight) on hormonal responses to exercise in the heat were examined in six heat-acclimated male volunteers. On the day following dehydration, subjects performed light (approximately 25% maximal O2 consumption, 1.03 1 X min-1) exercise in a hot (49 degrees C, 20% relative humidity) environment for four consecutive 25-min intervals interspaced by 10-min rests; blood was obtained before exercise and at approximately 10 min before completion of each exercise period. During euhydration, plasma cortisol (PC) levels manifested significant decrements over time (e.g., time 0, 14.2 micrograms X 100 ml-1 vs. time 2, 8.9 micrograms X 100 ml-1), probably related to its diurnal periodicity. However, during hypohydration, levels of PC were increased and correlated with hypohydration intensity (e.g., time 0, 0, 3, 5, and 7% hypohydration, 14.2, 16.5, 19.8, and 36.2 micrograms X 100 ml-1, respectively). Plasma renin activity (PRA) was increased significantly by hypohydration (e.g., time 0, euhydrated vs. 3%, 3.7 vs. 6.2 units) but was unaffected by exercise in the heat. Plasma aldosterone (ALD) levels were generally increased by exercise in the heat (e.g., time 0 vs. time 4, 3% hypohydration, 12.1 vs. 18.7 ng X 100 ml-1). Regression analysis illustrated that graded intensities of hypohydration were correlated with incremented PRA and ALD through 5% hypohydration. Conversely, PC was incrementally elevated through 7% hypohydration.(

ABSTRACT

TRUNCATED AT 250 WORDS)

Authors

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

Pub Type(s)

Journal Article

Language

eng

PubMed ID

3908440

Citation

Francesconi, R P., et al. "Plasma Hormonal Responses at Graded Hypohydration Levels During Exercise-heat Stress." Journal of Applied Physiology (Bethesda, Md. : 1985), vol. 59, no. 6, 1985, pp. 1855-60.
Francesconi RP, Sawka MN, Pandolf KB, et al. Plasma hormonal responses at graded hypohydration levels during exercise-heat stress. J Appl Physiol. 1985;59(6):1855-60.
Francesconi, R. P., Sawka, M. N., Pandolf, K. B., Hubbard, R. W., Young, A. J., & Muza, S. (1985). Plasma hormonal responses at graded hypohydration levels during exercise-heat stress. Journal of Applied Physiology (Bethesda, Md. : 1985), 59(6), 1855-60.
Francesconi RP, et al. Plasma Hormonal Responses at Graded Hypohydration Levels During Exercise-heat Stress. J Appl Physiol. 1985;59(6):1855-60. PubMed PMID: 3908440.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Plasma hormonal responses at graded hypohydration levels during exercise-heat stress. AU - Francesconi,R P, AU - Sawka,M N, AU - Pandolf,K B, AU - Hubbard,R W, AU - Young,A J, AU - Muza,S, PY - 1985/12/1/pubmed PY - 1985/12/1/medline PY - 1985/12/1/entrez SP - 1855 EP - 60 JF - Journal of applied physiology (Bethesda, Md. : 1985) JO - J. Appl. Physiol. VL - 59 IS - 6 N2 - The effects of graded levels of hypohydration (3, 5, and 7% of body weight) on hormonal responses to exercise in the heat were examined in six heat-acclimated male volunteers. On the day following dehydration, subjects performed light (approximately 25% maximal O2 consumption, 1.03 1 X min-1) exercise in a hot (49 degrees C, 20% relative humidity) environment for four consecutive 25-min intervals interspaced by 10-min rests; blood was obtained before exercise and at approximately 10 min before completion of each exercise period. During euhydration, plasma cortisol (PC) levels manifested significant decrements over time (e.g., time 0, 14.2 micrograms X 100 ml-1 vs. time 2, 8.9 micrograms X 100 ml-1), probably related to its diurnal periodicity. However, during hypohydration, levels of PC were increased and correlated with hypohydration intensity (e.g., time 0, 0, 3, 5, and 7% hypohydration, 14.2, 16.5, 19.8, and 36.2 micrograms X 100 ml-1, respectively). Plasma renin activity (PRA) was increased significantly by hypohydration (e.g., time 0, euhydrated vs. 3%, 3.7 vs. 6.2 units) but was unaffected by exercise in the heat. Plasma aldosterone (ALD) levels were generally increased by exercise in the heat (e.g., time 0 vs. time 4, 3% hypohydration, 12.1 vs. 18.7 ng X 100 ml-1). Regression analysis illustrated that graded intensities of hypohydration were correlated with incremented PRA and ALD through 5% hypohydration. Conversely, PC was incrementally elevated through 7% hypohydration.(ABSTRACT TRUNCATED AT 250 WORDS) SN - 8750-7587 UR - https://www.unboundmedicine.com/medline/citation/3908440/Plasma_hormonal_responses_at_graded_hypohydration_levels_during_exercise_heat_stress_ L2 - http://journals.physiology.org/doi/full/10.1152/jappl.1985.59.6.1855?url_ver=Z39.88-2003&rfr_id=ori:rid:crossref.org&rfr_dat=cr_pub=pubmed DB - PRIME DP - Unbound Medicine ER -