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Cited by 769Thermoregulation and physiological responsesCardiovascular and exercise physiologySports Performance and Training

Influence of graded dehydration on hyperthermia and cardiovascular drift during exercise

Montain, S. J., Coyle, E. F.·1992·Journal of Applied Physiology
DOI 10.1152/jappl.1992.73.4.1340
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Abstract

This investigation determined the effect of different rates of dehydration, induced by ingesting different volumes of fluid during prolonged exercise, on hyperthermia, heart rate (HR), and stroke volume (SV). On four different occasions, eight endurance-trained cyclists [age 23 +/- 3 (SD) yr, body wt 71.9 +/- 11.6 kg, maximal O2 consumption 4.72 +/- 0.33 l/min] cycled at a power output equal to 62-67% maximal O2 consumption for 2 h in a warm environment (33 degrees C dry bulb, 50% relative humidity, wind speed 2.5 m/s). During exercise, they randomly received no fluid (NF) or ingested a small (SF), moderate (MF), or large (LF) volume of fluid that replaced 20 +/- 1, 48 +/- 1, and 81 +/- 2%, respectively, of the fluid lost in sweat during exercise. The protocol resulted in graded magnitudes of dehydration as body weight declined 4.2 +/- 0.1, 3.4 +/- 0.1, 2.3 +/- 0.1, and 1.1 +/- 0.1%, respectively, during NF, SF, MF, and LF. After 2 h of exercise, esophageal temperature (Tes), HR, and SV were significantly different among the four trials (P < 0.05), with the exception of NF and SF. The magnitude of dehydration accrued after 2 h of exercise in the four trials was linearly related with the increase in Tes (r = 0.98, P < 0.02), the increase in HR (r = 0.99, P < 0.01), and the decline in SV (r = 0.99, P < 0.01). LF attenuated hyperthermia, apparently because of higher skin blood flow, inasmuch as forearm blood flow was 20-22% higher than during SF and NF at 105 min (P < 0.05). There were no differences in sweat rate among the four trials. In each subject, the increase in Tes from 20 to 120 min of exercise was highly correlated to the increase in serum osmolality (r = 0.81-0.98, P < 0.02-0.19) and the increase in serum sodium concentration (r = 0.87-0.99, P < 0.01-0.13) from 5 to 120 min of exercise. In summary, the magnitude of increase in core temperature and HR and the decline in SV are graded in proportion to the amount of dehydration accrued during exercise.

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Authors
Montain, S. J., & Coyle, E. F.
Affiliations
The University of Texas at Austin (US)
ORCID
Coyle, E. F.
Venue
Journal of Applied Physiology
Publisher
American Physiological Society
Published
1992-10-01
Volume
73
Issue
4
Pages
1340-1350
ISSN
  • 0161-7567 (ISSN-L)
  • 8750-7587
  • 1522-1601
DOI
10.1152/jappl.1992.73.4.1340
OpenAlex
W1910883221
Cited by
769
References
16
Citations by year
2026: 18 · 2025: 13 · 2024: 16 · 2023: 17 · 2022: 11 · 2021: 22 · 2020: 31 · 2019: 38 · 2018: 25 · 2017: 28 · 2016: 29 · 2015: 41 · 2014: 49 · 2013: 46 · 2012: 32
FWCI
3.03
Type
journal article
Language
en
Open access
closed
Locations
  • Journal of Applied Physiology (publishedVersion)
  • PubMed (publishedVersion)
Topics
  • Health Sciences › Medicine › Physiology › Thermoregulation and physiological responses
  • Health Sciences › Medicine › Complementary and alternative medicine › Cardiovascular and exercise physiology
  • Health Sciences › Medicine › Orthopedics and Sports Medicine › Sports Performance and Training
Keywords
exercise hyperthermia, cardiovascular drift, fluid intake, endurance cyclists, esophageal temperature, heart rate, stroke volume, skin blood flow, forearm blood flow, serum osmolality, serum sodium, sweat rate, heat stress, fluid replacement, endurance training, thermoregulation
MeSH terms
Adult, Blood Volume, Body Temperature Regulation, Cardiac Output, Dehydration, Drinking, Heart Rate, Hematocrit, Hemodynamics, Humans, Osmolar Concentration, Plethysmography, Potassium, Skin Temperature, Sodium, Sweating, Exercise

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