Humans show a marked variation in their thermoregulatory behaviour.
In this review, an attempt was made to determine in how far this
variation is caused by differences in sex, age, anthropometric
measures, hydration state and circadian rhythm and to which underlying
parameters their effect can be ascribed.
For the following factors (in approximate ranking order of significance),
such parameters have been found:
- State of acclimatization
The state of acclimatization is defined by the sweat characteristics
(high state of acclimatization implies high maximal sweat
rate, high gain and/or low setpoint for sweat rate-Tcore relation.
improved sweat distribution) and by the circulatory capacity (high
state of acclimatization: more constant blood pressure and blood
volume; lower heart frequency; high stroke volume).
Physical fitness
The effect of physical fitness on
determined by circulatory capacity. As
the state of acclimatization, it is
acclimatization are strongly related.
- Hydration state
thermoregulation is mainly
this is also a parameter for
obvious that fitness and
The influence of the state of hydration on thermoregulatory function
is determined by two parameters:
1 Plasma osmolality: the plasma osmolality affects either the
thermoregulatory centres in the brain or directly the function
of the sweat gland. These effects may be ion specific ( Na+ •
ca++).
2 Plasma volume: changes in plasma volume and consequently blood
viscosity influence cardiac efficiency and through this the
strain of the body during heat stress.
- Anthropometric measures
These will have a physical influence through: heat exchange surface
area (body surface), insulation (fat) and weight load (inactive
body mass).
- Time of day
The influence of the time of day on thermoregulation is determined
by the related variations in sweat characteristics, skin blood flow
and body temperature. In how far this also influences body heat strain and heat tolerance
is yet unknown.
The factors sex and age are supposed to be of little importance for
the reactions to heat stress, as effects ascribed to these factors
can be described by the above mentioned factors with their parameters.
At the end of this report, the findings will be expressed in propositions
for the determination of the selected factors and parameters.
Funding
TNO Institute for Perception
History
School
Design
Citation
HAVENITH, G., 1985. Individual differences in thermoregulatory control, a review. Soesterberg, NL: TNO Institute for Perception, 86pp.
Publisher
TNO Institute for Perception
Version
VoR (Version of Record)
Publisher statement
This work is made available according to the conditions of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0) licence. Full details of this licence are available at: https://creativecommons.org/licenses/by-nc-nd/4.0/