Sweat Rate Prediction Equations for Outdoor Exercise with Transient Solar Radiation
ARMY RESEARCH INST OF ENVIRONMENTAL MEDICINE NATICK MA THERMAL AND MOUNTAIN MEDICINE DIVISION
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We investigated the validity of employing a fuzzy piecewise prediction equation PW defined by sweat rate msw, gsq mh 147 1.527xEreq - 0.87xEmax, which integrates evaporation required Ereq and the maximum evaporative capacity of the environment Emax. Heat exchange and physiological responses were determined throughout the trials. Environmental conditions were ambient temperature Ta 16-26 deg C, relative humidity RH 51-55, and wind speed V 0.5-1.5 ms. Volunteers wore military fatigues clothing evaporative potential imclo 0.33 and carried loads 15-31 kg while marching 14-37 km over variable terrains either at night N 77, trials 1-5 or night with increasing daylight N 33, trials 6 and 7. PW was modified Pw,sol for transient solar radiation Rsol, W determined from measured solar loads and verified in trials 6 and 7. PW provided a valid msw prediction during night trials 1-5 matching previous laboratory values and verified by bootstrap correlation rbs of 0.81, SE or - 0.014, SEE or - 69.2 gsq mh. For trials 6 and 7, Ereq and Emax components included Rsol applying a modified equation Pw,sol, in which msw 147 1.527xEreq,sol - 0.87 xEmax. Linear prediction of msw 0.72 x Pw,sol 135 N 33 was validated R2 0.92 SEE or -33.8 gsq mh with PW beta-coefficients unaltered during field marches between 16 deg C and 26 deg C Ta for msw or 700 gsq mh. PW was additionally derived for cool laboratorynight conditions Ta 20 deg C in which Ereq is low but Emax is high, as PW,cool gsq mh 350 1.527xEreq - 0.87xEmax. These sweat prediction equations allow valid tools for civilian, sports, and military medicine communities to predict water needs during a variety of heat stressexercise conditions.
- Anatomy and Physiology
- Stress Physiology