TY - JOUR

T1 - Sweat rate prediction equations for outdoor exercise with transient solar radiation

AU - Gonzalez, Richard R.

AU - Cheuvront, Samuel N.

AU - Ely, Brett R.

AU - Moran, Daniel S.

AU - Hadid, Amir

AU - Endrusick, Thomas L.

AU - Sawka, Michael N.

PY - 2012/4/15

Y1 - 2012/4/15

N2 - We investigated the validity of employing a fuzzy piecewise prediction equation (PW) [Gonzalez et al. J Appl Physiol 107: 379-388, 2009] defined by sweat rate (m sw, g · m -2 · h -1) = 147 + 1.527·(E req) - 0.87 · (E max), which integrates evaporation required (E req) and the maximum evaporative capacity of the environment (E max). Heat exchange and physiological responses were determined throughout the trials. Environmental conditions were ambient temperature (T a) = 16-26°C, relative humidity (RH) = 51-55%, and wind speed (V) = 0.5-1.5 m/s. Volunteers wore military fatigues [clothing evaporative potential (i m/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 (Ṗw,sol) for transient solar radiation (R sol, W) determined from measured solar loads and verified in trials 6 and 7. PW provided a valid m sw prediction during night trials (1-5) matching previous laboratory values and verified by bootstrap correlation (r bs of 0.81, SE ± 0.014, SEE = ± 69.2 g · m -2 · h -1). For trials 6 and 7, E req and E max components included R sol applying a modified equation Ṗw,sol, in which m sw = 147 + 1.527 · (E req,sol) - 0.87 · (E max). Linear prediction of m sw = 0.72 · Ṗw,sol + 135 (N = 33) was validated (R 2 = 0.92; SEE = ±33.8 g · m -2 · h -1) with PW β-coefficients unaltered during field marches between 16°C and 26°C T a for m sw ≤ 700 g · m -2 · h -1. PW was additionally derived for cool laboratory/night conditions (T a < 20°C) in which E req is low but E max is high, as: PW,cool (g · m -2 · h -1) = 350 + 1.527 · E req - 0.87 · E max. 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.

AB - We investigated the validity of employing a fuzzy piecewise prediction equation (PW) [Gonzalez et al. J Appl Physiol 107: 379-388, 2009] defined by sweat rate (m sw, g · m -2 · h -1) = 147 + 1.527·(E req) - 0.87 · (E max), which integrates evaporation required (E req) and the maximum evaporative capacity of the environment (E max). Heat exchange and physiological responses were determined throughout the trials. Environmental conditions were ambient temperature (T a) = 16-26°C, relative humidity (RH) = 51-55%, and wind speed (V) = 0.5-1.5 m/s. Volunteers wore military fatigues [clothing evaporative potential (i m/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 (Ṗw,sol) for transient solar radiation (R sol, W) determined from measured solar loads and verified in trials 6 and 7. PW provided a valid m sw prediction during night trials (1-5) matching previous laboratory values and verified by bootstrap correlation (r bs of 0.81, SE ± 0.014, SEE = ± 69.2 g · m -2 · h -1). For trials 6 and 7, E req and E max components included R sol applying a modified equation Ṗw,sol, in which m sw = 147 + 1.527 · (E req,sol) - 0.87 · (E max). Linear prediction of m sw = 0.72 · Ṗw,sol + 135 (N = 33) was validated (R 2 = 0.92; SEE = ±33.8 g · m -2 · h -1) with PW β-coefficients unaltered during field marches between 16°C and 26°C T a for m sw ≤ 700 g · m -2 · h -1. PW was additionally derived for cool laboratory/night conditions (T a < 20°C) in which E req is low but E max is high, as: PW,cool (g · m -2 · h -1) = 350 + 1.527 · E req - 0.87 · E max. 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.

KW - Environmental indexes

KW - Fluid replacement

KW - Load carriage

KW - Modeling

KW - Thermoregulation

UR - http://www.scopus.com/inward/record.url?scp=84860316470&partnerID=8YFLogxK

U2 - 10.1152/japplphysiol.01056.2011

DO - 10.1152/japplphysiol.01056.2011

M3 - ???researchoutput.researchoutputtypes.contributiontojournal.article???

C2 - 22241058

AN - SCOPUS:84860316470

SN - 8750-7587

VL - 112

SP - 1300

EP - 1310

JO - Journal of Applied Physiology

JF - Journal of Applied Physiology

IS - 8

ER -