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Endocrine responses during exercise-heat stress: effects of prior isotonic and hypotonic intravenous rehydration.
Eur J Appl Physiol Occup Physiol. 1998 Feb; 77(3):242-8.EJ

Abstract

Exercise following exercise-induced dehydration (EID) has been shown to elevate concentrations of plasma norepinephrine (NE) and hypothalamic-pituitary-adrenal axis hormones. However, it is not known how intravenous (i.v.) rehydration (Rh) with isotonic (ISO) or hypotonic (HYPO) saline affects these hormone concentrations. It was hypothesized that HYPO, versus ISO, would lead to lower plasma NE and cortisol concentrations ([CORT]) during subsequent exercise following EID due to a decrease in plasma sodium concentration [Na+]. Eight non-heat acclimated men completed three experimental treatments (counterbalanced design) immediately following EID (33 degrees C) to -4% body mass loss. The Rh treatments were i.v. 0.9% NaCl (ISO, 25 ml x kg[-1]), i.v. 0.45% NaCl (HYPO, 25 ml x kg[-1]), and no fluid (NF). After Rh and rest (2 h total), the subjects walked at 53-54 percent of maximal O2 uptake for 45 min at 36 degrees C. After Rh, the following observations were made before/during exercise: percentage change in plasma volume (PV) was lower in NF compared to ISO and HYPO but similar between ISO and HYPO; delta[Na+] was similar between ISO and NF and higher in ISO compared to HYPO; delta plasma NE was higher in NF compared to ISO and HYPO, but similar between ISO and HYPO; delta plasma [CORT] was higher in NF compared to ISO and HYPO and higher in ISO compared to HYPO; rectal temperature was higher in NF compared to ISO and HYPO. These data would suggest that sympathetic nervous activity and [CORT] during exercise, subsequent to EID and Rh, was affected by lower PV (probably through cardiopulmonary baroreflexes) as well as core temperature. Furthermore, [CORT] was affected by delta[Na+] after Rh through an unknown mechanism.

Authors+Show Affiliations

Department of Sport, Leisure, and Exercise Science, University of Connecticut, Storrs, USA.No 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

9535585

Citation

Castellani, J W., et al. "Endocrine Responses During Exercise-heat Stress: Effects of Prior Isotonic and Hypotonic Intravenous Rehydration." European Journal of Applied Physiology and Occupational Physiology, vol. 77, no. 3, 1998, pp. 242-8.
Castellani JW, Maresh CM, Armstrong LE, et al. Endocrine responses during exercise-heat stress: effects of prior isotonic and hypotonic intravenous rehydration. Eur J Appl Physiol Occup Physiol. 1998;77(3):242-8.
Castellani, J. W., Maresh, C. M., Armstrong, L. E., Kenefick, R. W., Riebe, D., Echegaray, M., Kavouras, S., & Castracane, V. D. (1998). Endocrine responses during exercise-heat stress: effects of prior isotonic and hypotonic intravenous rehydration. European Journal of Applied Physiology and Occupational Physiology, 77(3), 242-8.
Castellani JW, et al. Endocrine Responses During Exercise-heat Stress: Effects of Prior Isotonic and Hypotonic Intravenous Rehydration. Eur J Appl Physiol Occup Physiol. 1998;77(3):242-8. PubMed PMID: 9535585.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Endocrine responses during exercise-heat stress: effects of prior isotonic and hypotonic intravenous rehydration. AU - Castellani,J W, AU - Maresh,C M, AU - Armstrong,L E, AU - Kenefick,R W, AU - Riebe,D, AU - Echegaray,M, AU - Kavouras,S, AU - Castracane,V D, PY - 1998/4/16/pubmed PY - 1998/4/16/medline PY - 1998/4/16/entrez SP - 242 EP - 8 JF - European journal of applied physiology and occupational physiology JO - Eur J Appl Physiol Occup Physiol VL - 77 IS - 3 N2 - Exercise following exercise-induced dehydration (EID) has been shown to elevate concentrations of plasma norepinephrine (NE) and hypothalamic-pituitary-adrenal axis hormones. However, it is not known how intravenous (i.v.) rehydration (Rh) with isotonic (ISO) or hypotonic (HYPO) saline affects these hormone concentrations. It was hypothesized that HYPO, versus ISO, would lead to lower plasma NE and cortisol concentrations ([CORT]) during subsequent exercise following EID due to a decrease in plasma sodium concentration [Na+]. Eight non-heat acclimated men completed three experimental treatments (counterbalanced design) immediately following EID (33 degrees C) to -4% body mass loss. The Rh treatments were i.v. 0.9% NaCl (ISO, 25 ml x kg[-1]), i.v. 0.45% NaCl (HYPO, 25 ml x kg[-1]), and no fluid (NF). After Rh and rest (2 h total), the subjects walked at 53-54 percent of maximal O2 uptake for 45 min at 36 degrees C. After Rh, the following observations were made before/during exercise: percentage change in plasma volume (PV) was lower in NF compared to ISO and HYPO but similar between ISO and HYPO; delta[Na+] was similar between ISO and NF and higher in ISO compared to HYPO; delta plasma NE was higher in NF compared to ISO and HYPO, but similar between ISO and HYPO; delta plasma [CORT] was higher in NF compared to ISO and HYPO and higher in ISO compared to HYPO; rectal temperature was higher in NF compared to ISO and HYPO. These data would suggest that sympathetic nervous activity and [CORT] during exercise, subsequent to EID and Rh, was affected by lower PV (probably through cardiopulmonary baroreflexes) as well as core temperature. Furthermore, [CORT] was affected by delta[Na+] after Rh through an unknown mechanism. SN - 0301-5548 UR - https://www.unboundmedicine.com/medline/citation/9535585/Endocrine_responses_during_exercise_heat_stress:_effects_of_prior_isotonic_and_hypotonic_intravenous_rehydration_ L2 - https://medlineplus.gov/exerciseandphysicalfitness.html DB - PRIME DP - Unbound Medicine ER -