The Use of Theoretical Models in the Study of
Thermoregulation in Man
J. A. J. STOLWIJK
With 5 Figures
Abstract
A somewhat unexpected benefit of the development of theoretical models
of body temperature regulation has been a significant improvement in communication between research and practice in the field of thermoregulation. A computer
program containing the best available insight into and quantitative estimates of
physiological responses to environment and exercise can be used by those interested in practical problems to obtain the best quantitative prediction of the responses to any particular combination of environment and work load.
Introduction
In the study of a complex regulatory system such as the regulation of
body temperature in homoiotherms, there are relatively few measurements
of important parameters which can be made easily and conveniently. The
result tends to be that because a measurement is accessible and in widespread
use we begin to give more weight to the measurement than it deserves.
Especially in dynamic conditions, a measurement, e.g. of rectal temperature
in man, is a notoriously poor indicator of total body heat content, average
core temperature, temperature of central thermo receptors or rate of change
of body heat content.
On the other hand, again similar to other physiological regulatory mechanisms, the system is so effective in maintaining body temperature that a
sustained thermal load results in only an insignificant displacement of
central body temperatures. Thus interpretation of steady state data, in an
attempt to gain insight into the mechanism of thermoregulation, allows
only very moderate progress.
Since long ago, physiologists have realized either intuitively or explicitly that the study of a complete and intact system can only proceed
along certain lines. More recently, the engineering profession has developed
a formal approach to the study of complex sytems with feedback control.
In general the formal solutions which they have obtained only cover relatively simple systems and then only if certain criteria are met. The approach
Thermoregulation in Man
J. A. J. STOLWIJK
With 5 Figures
Abstract
A somewhat unexpected benefit of the development of theoretical models
of body temperature regulation has been a significant improvement in communication between research and practice in the field of thermoregulation. A computer
program containing the best available insight into and quantitative estimates of
physiological responses to environment and exercise can be used by those interested in practical problems to obtain the best quantitative prediction of the responses to any particular combination of environment and work load.
Introduction
In the study of a complex regulatory system such as the regulation of
body temperature in homoiotherms, there are relatively few measurements
of important parameters which can be made easily and conveniently. The
result tends to be that because a measurement is accessible and in widespread
use we begin to give more weight to the measurement than it deserves.
Especially in dynamic conditions, a measurement, e.g. of rectal temperature
in man, is a notoriously poor indicator of total body heat content, average
core temperature, temperature of central thermo receptors or rate of change
of body heat content.
On the other hand, again similar to other physiological regulatory mechanisms, the system is so effective in maintaining body temperature that a
sustained thermal load results in only an insignificant displacement of
central body temperatures. Thus interpretation of steady state data, in an
attempt to gain insight into the mechanism of thermoregulation, allows
only very moderate progress.
Since long ago, physiologists have realized either intuitively or explicitly that the study of a complete and intact system can only proceed
along certain lines. More recently, the engineering profession has developed
a formal approach to the study of complex sytems with feedback control.
In general the formal solutions which they have obtained only cover relatively simple systems and then only if certain criteria are met. The approach