Advanced

Predicted Heat Strain (PHS) model and the sweat loss in an extremely hot climate

Halder, Amitava LU ; Kuklane, Kalev LU ; Petersson, Jakob LU ; Hursa Sajatovic, Anica LU and Gao, Chuansi LU (2019) International Conference on Environmental Ergonomics 2019
Abstract
Introduction: The aim was to study if the evaporative water loss can be predicted enough accurately for hydration recommendations by ISO 7933 – Predicted Heat Strain (PHS) model during a student laboratory exercise in an extremely hot environment.

Method: Twelve young healthy students (8 males and 4 females), unacclimatized to heat, were exposed in a climatic chamber at 50˚C, 30% relative humidity and 0.4 m·s-1 air velocity for 45 minutes. They had a mean (SD) age of 25.1 (2.6) years, height 175.6 (6.9) cm, weight 72.3 (11.0) kg, VO2max 54.9 (6.5) mL·min-1·kg-1, and HRmax 194 (6) bpm. The men and women performed bicycling for 6-minutes at workloads of 150 and 100 Watts (W), when the metabolic rates (M) calculated found 363 and 290... (More)
Introduction: The aim was to study if the evaporative water loss can be predicted enough accurately for hydration recommendations by ISO 7933 – Predicted Heat Strain (PHS) model during a student laboratory exercise in an extremely hot environment.

Method: Twelve young healthy students (8 males and 4 females), unacclimatized to heat, were exposed in a climatic chamber at 50˚C, 30% relative humidity and 0.4 m·s-1 air velocity for 45 minutes. They had a mean (SD) age of 25.1 (2.6) years, height 175.6 (6.9) cm, weight 72.3 (11.0) kg, VO2max 54.9 (6.5) mL·min-1·kg-1, and HRmax 194 (6) bpm. The men and women performed bicycling for 6-minutes at workloads of 150 and 100 Watts (W), when the metabolic rates (M) calculated found 363 and 290 W·m-2, respectively. Moreover, the students did step test at 60 steps·min-1 for 5-minutes with estimated M being 215 W·m-2. They were standing most of the time (34 min) (M = 80 W·m-2). Time weighted average M for males and females were 133 and 123 W·m-2, respectively, for the whole exposure duration. Clothing insulation, Icl = 0.4 clo and moisture permeability index, im = 0.42 were input to PHS model simulation. The actual water loss by evaporation was determined by subject’s dressed body weight difference before and after exposure.

Results: The actual mean (SD) total water evaporated was 461.3 (176.7) g. The predicted total water loss was 427.4 (39.2) g by the PHS model. There was no significant (p = .514) difference between the actual and the predicted water loss. However, the original estimation of evaporative sweat was found only 270.1 g.

Conclusions: These results suggest that it is challenging to predict the water loss in continuous extreme heat exposure at 50˚C using ISO 7933 – PHS model. It should be used cautiously to predict the dehydration, and plan for drinking in extremely hot climates.
(Less)
Please use this url to cite or link to this publication:
author
organization
publishing date
type
Contribution to conference
publication status
published
subject
keywords
Water loss, sweat loss, Prediction models, Dehydration, Recommendation
conference name
International Conference on Environmental Ergonomics 2019
conference location
Amsterdam, Netherlands
conference dates
2019-07-07 - 2019-07-12
language
English
LU publication?
yes
id
9e3a3b91-fe95-4711-9253-e1d5c06e69a4
date added to LUP
2019-07-17 14:09:05
date last changed
2019-09-16 14:57:39
@misc{9e3a3b91-fe95-4711-9253-e1d5c06e69a4,
  abstract     = {Introduction: The aim was to study if the evaporative water loss can be predicted enough accurately for hydration recommendations by ISO 7933 – Predicted Heat Strain (PHS) model during a student laboratory exercise in an extremely hot environment.<br/><br/>Method: Twelve young healthy students (8 males and 4 females), unacclimatized to heat, were exposed in a climatic chamber at 50˚C, 30% relative humidity and 0.4 m·s-1 air velocity for 45 minutes. They had a mean (SD) age of 25.1 (2.6) years, height 175.6 (6.9) cm, weight 72.3 (11.0) kg, VO2max 54.9 (6.5) mL·min-1·kg-1, and HRmax 194 (6) bpm. The men and women performed bicycling for 6-minutes at workloads of 150 and 100 Watts (W), when the metabolic rates (M) calculated found 363 and 290 W·m-2, respectively. Moreover, the students did step test at 60 steps·min-1 for 5-minutes with estimated M being 215 W·m-2. They were standing most of the time (34 min) (M = 80 W·m-2). Time weighted average M for males and females were 133 and 123 W·m-2, respectively, for the whole exposure duration. Clothing insulation, Icl = 0.4 clo and moisture permeability index, im = 0.42 were input to PHS model simulation. The actual water loss by evaporation was determined by subject’s dressed body weight difference before and after exposure.<br/><br/>Results: The actual mean (SD) total water evaporated was 461.3 (176.7) g. The predicted total water loss was 427.4 (39.2) g by the PHS model. There was no significant (p = .514) difference between the actual and the predicted water loss. However, the original estimation of evaporative sweat was found only 270.1 g.<br/><br/>Conclusions: These results suggest that it is challenging to predict the water loss in continuous extreme heat exposure at 50˚C using ISO 7933 – PHS model. It should be used cautiously to predict the dehydration, and plan for drinking in extremely hot climates.<br/>},
  author       = {Halder, Amitava and Kuklane, Kalev and Petersson, Jakob and Hursa Sajatovic, Anica and Gao, Chuansi},
  keyword      = {Water loss,sweat loss,Prediction  models,Dehydration,Recommendation},
  language     = {eng},
  location     = {Amsterdam, Netherlands},
  month        = {07},
  title        = {Predicted Heat Strain (PHS) model and the sweat loss in an extremely hot climate},
  year         = {2019},
}