The influence of skin friction on the perception of fabric texture and pleasantness (acceptability) was studied by exposing eight men to a sequence of environmental conditions: neutral (comfortable), hot-dry, hot-humid, and return to neutral. The air and dew point temperatutes ( T a : T dp ) of these conditions were 23:15°C, 35:15°C, 35 :29°C, and 23:15°C, respectively; air velocity was 0.05 m/s. During each condition, which lasted 20 minutes, six different fabrics (worsted wool, brushed cotton, cotton, ' Presented at

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Gonzalez RR, Cheuvront SN, Montain SJ, Goodman DA, Blanchard LA, Berglund LG, Sawka MN. Expanded prediction equations of human sweat loss and water needs. J Appl Physiol 107: 379 -388, 2009. First published April 30, 2009 doi:10.1152/japplphysiol.00089.2009.-The Institute of Medicine expressed a need for improved sweating rate (ṁ sw) prediction models that calculate hourly and daily water needs based on metabolic rate, clothing, and environment. More than 25 years ago, the original Shapiro prediction equation (OSE) was formulated as ṁ sw, where Ereq is required evaporative heat loss and Emax is maximum evaporative power of the environment; OSE was developed for a limited set of environments, exposures times, and clothing systems. Recent evidence shows that OSE often overpredicts fluid needs. Our study developed a corrected OSE and a new ṁ sw prediction equation by using independent data sets from a wide range of environmental conditions, metabolic rates (rest to Յ450 W/m 2 ), and variable exercise durations. Whole body sweat losses were carefully measured in 101 volunteers (80 males and 21 females; Ͼ500 observations) by using a variety of metabolic rates over a range of environmental conditions (ambient temperature, 15-46°C; water vapor pressure, 0.27-4.45 kPa; wind speed, 0.4 -2.5 m/s), clothing, and equipment combinations and durations (2-8 h). Data are expressed as grams per square meter per hour and were analyzed using fuzzy piecewise regression. OSE overpredicted sweating rates (P Ͻ 0.003) compared with observed ṁ sw. Both the correction equation (OSEC), ṁ sw ϭ 147 ⅐ exp (0.0012 ⅐ OSE), and a new piecewise (PW) equation, ṁ sw ϭ 147 ϩ 1.527 ⅐ Ereq Ϫ 0.87 ⅐ Emax were derived, compared with OSE, and then cross-validated against independent data (21 males and 9 females; Ͼ200 observations). OSEC and PW were more accurate predictors of sweating rate (58 and 65% more accurate, P Ͻ 0.01) and produced minimal error (standard error estimate Ͻ 100 g ⅐ m Ϫ2 ⅐ h Ϫ1 ) for conditions both within and outside the original OSE domain of validity. The new equations provide for more accurate sweat predictions over a broader range of conditions with applications to public health, military, occupational, and sports medicine settings. thermoregulation; modeling; fluid balance; hydration; fluid replacement DAILY WATER NEEDS can be determined from "minimal" water losses and expected increases in different water flux avenues (11,22). Metabolic water production and respiratory losses often offset each other, and fecal losses are usually small (11,22). Urinary losses primarily depend on hydration status and osmolar load, but sweat represents the largest potential avenue of body water loss. Knowledge of sweat losses is therefore critical for calculating water needs for active populations, particularly when exposed to heat stress (11,22). For example, military potable water planning relies on water tables generated from existing prediction equations (15, 25), and similar nomograms have been generated for public health purposes (11). Al...