Estimation of metabolic rate from cardiac frequency for field studies: correcting for 'thermal pulses'

摘要

(1) Metabolic rate in field studies is usually estimated during short measurements, but may be estimated for complete shifts by linking these measurements to cardiac frequency. (2) An increase of body temperature leads to a rise of cardiac frequency; this increase of cardiac frequency from thermal origin ("thermal pulses") should be taken into account when metabolic rate is to be calculated out of cardiac frequency. (3) By improving a heuristic methodology proposed by Vogt et al. (Le Travail Humaine 33 (1970) 125), it is possible to determine the contribution of thermal pulses to cardiac frequency for complete shifts in field studies, if body core temperature is measured continuously. (4) This methodology was applied in a study where strain of coal miners at hot working places underground was determined during 112 shifts the thermal pulses constitute 31% of the increase of cardiac frequency above resting values in the mean of all shifts-if the rise of metabolic rates above resting values is determined from cardiac frequency, then the consideration of thermal pulses reduces the overestimation of metabolic rates by 25%.