Evaluation of different levels of hydration using a new physiological strain index
- 1 September 1998
- journal article
- research article
- Published by American Physiological Society in American Journal of Physiology-Regulatory, Integrative and Comparative Physiology
- Vol. 275 (3), R854-R860
- https://doi.org/10.1152/ajpregu.1998.275.3.r854
Abstract
A physiological strain index (PSI), based on rectal temperature (Tre) and heart rate (HR), was recently suggested for evaluating heat stress. The purpose of this study was to evaluate the PSI for different combinations of hydration level and exercise intensity. This index was applied to two databases. The first database was obtained from eight endurance-trained men dehydrated to four different levels (1.1, 2.3, 3.4, and 4.2% of body wt) during 120 min of cycling at a power output of 62–67% maximum O2 consumption (V˙o2 max) in the heat [33°C and 50% relative humidity (RH)]. The second database was obtained from nine men performing exercise in the heat (30°C and 50% RH) for 50 min. These subjects completed a matrix of nine trials of exercise on a treadmill at three exercise intensities (25, 45, and 65%V˙o2 max) and three hydration levels (euhydration and hypohydration at 3 and 5% of body wt). Tre, HR, esophageal temperature (Tes), and local sweating rate were measured. PSI (obtained from either Tre or Tes) significantly (P < 0.05) differentiated among all exposures in both databases categorized by exercise intensity and hydration level, and we assessed the strain on a scale ranging from 0 to 10. Therefore, PSI applicability was extended for heat strain associated with hypohydration and continues to provide the potential to be universally accepted.Keywords
This publication has 22 references indexed in Scilit:
- Perceived exertion as an indicator of somatic stressJournal of Rehabilitation Medicine, 2019
- Effect of fluid ingestion on muscle metabolism during prolonged exerciseJournal of Applied Physiology, 1996
- Predicting heart rate response to various metabolic rates, environments, and clothingJournal of Applied Physiology, 1995
- Physiological consequences of hypohydrationMedicine & Science in Sports & Exercise, 1992
- Application of the relative summary climatic indices during work in heat for ergonomic purposesErgonomics, 1989
- Prediction modeling of physiological responses and human performance in the heatComputers in Biology and Medicine, 1986
- Seventy-five years of searching for a heat indexEnvironmental Research, 1980
- Temperature regulation and hypohydration: a singular viewJournal of Applied Physiology, 1979
- Temperature Regulation during Exercise Dehydration in ManActa Physiologica Scandinavica, 1970
- Body Temperature During Work at Different Environmental TemperaturesActa Physiologica Scandinavica, 1962