Physiological index of strain and body heat storage in hyperthermia

Abstract

Individual variability of a modified Craig index of physiological strain and body heat storage was determined, and the relationship between these parameters defined for five healthy, nonacclimatized male subjects exposed five times to each of three heat stress levels: 38°C, 54°C and 71°C at a vapor pressure of 10 mm Hg. This index contains the variables of heart rate, sweat rate and rate of rectal temperature change, measured by EKG, nude pre- and post-experimental weighings, and a rectal thermistor, respectively. Body heat storage was calculated from initial and terminal weighted mean skin and rectal temperatures. Subjects were sitting and wore 1 clo of body insulation. Individual and group variation for strain index and body heat storage was determined. The data show a linear relationship between these expressions over the thermal stress range investigated although individual variability was considerable at the higher stress levels. A statistically significant correlation between strain index and body heat storage is shown. Submitted on May 16, 1960

The cumulative heat strain index - a novel approach to assess the physiological strain induced by exercise-heat stress

“…The ®rst approach refers to the summation of changes in potentially relevant parameters (e.g. T re , skin temperature, f c and sweating) (Hall and Polte 1960;Robinson et al 1945). This approach was criticized on the basis that these physiological variables are interrelated and their summation is physiologically meaningless.…”

“…The ®rst is based on a combination of end-point values, or on changes from baseline values of selected parameters that are aected by heat stress [e.g. the index of physiological eect (Ep) (Robinson et al 1945), the index of physiological strain (Is) (Hall and Polte 1960), and the physiological strain index (PSI) (Moran et al 1998)]. This approach has intrinsic diculties associated with the application of the index, since physiological strain is time dependent and non-linear in its nature, and also dynamic changes are not considered when using end-point values or the changes from baseline.…”

Alleviation of Heat Strain by Cooling Different Body Areas during Red Pepper Harvest Work at WBGT 33℃

“…Total sweat rate (TSR) was calculated through the difference between before and after semi-nude body weight using a body scale (Sartorius, F150S, sensitivity 1 g, Germany). Body heat storage by Hardy and DuBois 24) , physiological strain index 25) , and the modified Craig Index 26) were calculated:…”

Effects of the Thermal Stress on Human Performance: A Review and Critique of Existing Methodology

“…It should be noted that these indices are primarily concerned with the physiological impact of heat on man's ability to work, and in cases where a particular index value serves as a limiting factor for performance, it is generally physical performance which is being referred to. Descriptions of the indices are adapted from more detailed reports (ASHRAE Guide and Data Book, 1965Book, 1966Bedford, 1961;Hall & Polte, 1961;Minard, 1964). Table 1 it becomes apparent that all are based, to some extent, on the previously described concept of physiological adequacy.…”