Accession Number : ADA559767


Title :   Sweat Rate Prediction Equations for Outdoor Exercise with Transient Solar Radiation


Descriptive Note : Journal article


Corporate Author : ARMY RESEARCH INST OF ENVIRONMENTAL MEDICINE NATICK MA THERMAL AND MOUNTAIN MEDICINE DIVISION


Personal Author(s) : Gonzalez, Richard R ; Cheuvront, Samuel N ; Ely, Brett R ; Moran, Daniel S ; Hadid, Amir ; Endrusick, Thomas L ; Sawka, Michael N


Full Text : http://www.dtic.mil/dtic/tr/fulltext/u2/a559767.pdf


Report Date : Jan 2012


Pagination or Media Count : 12


Abstract : We investigated the validity of employing a fuzzy piecewise prediction equation (PW) defined by sweat rate (msw, g/sq m/h) = 147 + 1.527x(Ereq) - 0.87x(Emax), 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 m/s. Volunteers wore military fatigues [clothing evaporative potential (im/clo) = 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 g/sq m/h). For trials 6 and 7, Ereq and Emax components included Rsol applying a modified equation Pw,sol, in which msw = 147 + 1.527x(Ereq,sol) - 0.87 x(Emax). Linear prediction of msw = 0.72 x Pw,sol + 135 (N = 33) was validated (R2 = 0.92; SEE = + or -33.8 g/sq m/h) with PW beta-coefficients unaltered during field marches between 16 deg C and 26 deg C Ta for msw or = 700 g/sq m/h. PW was additionally derived for cool laboratory/night conditions (Ta 20 deg C) in which Ereq is low but Emax is high, as: PW,cool (g/sq m/h) = 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 stress/exercise conditions.


Descriptors :   *PERSPIRATION , EXERCISE(PHYSIOLOGY) , OUTDOOR , PREDICTIONS , REPRINTS , SOLAR RADIATION


Subject Categories : Anatomy and Physiology
      Stress Physiology


Distribution Statement : APPROVED FOR PUBLIC RELEASE