Biophysical and physiological integration of proper clothing for exercise.

In this chapter, I have presented a potpourri of examples of proper clothing to wear during various exercise demands in different environments. These examples are not wholly exact for all persons. For example, during the 1984 Olympics in Los Angeles, clothing wear related to the particular environment was totally different. We have already described the aerodynamic necessities of cyclists and runners. At the other extreme, equestrians had to contend with a warm, moderately humid environment, plus a solar load that added to the effective heat stress, while wearing clothing having clo values of nearly 0.8-0.9, plus headgear that limited evaporative heat loss. Obviously, garments with high water vapor permeation and bellows properties were necessary. Runners in the marathon faced equal thermal challenges. In addition, they incurred variable levels of hypovolemia and cardiovascular strain. A. Salazar, for example, was advised to omit shower sprays, and he ran with a prototype high-permeability singlet. The excessive wetting plus time to maneuver to the spray was deemed of no value, since Mr. Salazar chafes easily from wet clothes (L. Armstrong, personnel communication). One interesting response to this advice is to consider the clothed runner as a wet globe thermometer under forced convection. A high-contact fabric, especially one like cotton, does allow evaporative cooling, provided that the skin-ambient vapor pressure gradient is not diminished by high relative humidity. Salts in sweat may reduce the skin's vapor pressure ; however, Woodcock and Breckenridge point out that "secreted sweat (especially with heat acclimation) is so dilute that no appreciable lowering of vapor pressure would occur unless sweat were concentrated many times by evaporation." Thus, the degree of "human" wet bulb depression simulated by a completely wet runner may or may not be an advantage, since all other variables are also constant (i.e., humidity, weight of clothing as in Figure 13, etc.) or the level of hypovolemia is not excessive and the person is fully heat acclimated. Problems such as these may be theoretical, but they serve to show that the thermal biophysics and physiology of exercise follow similar fundamental pathways that can be highly pertinent. As we sought to point out in this chapter, these pathways have merged in the last 30 years with developments such as warmth without bulk for backpackers (which is a welcomed contrast to heavy arctic wear), materials that allow athletes to remain somewhat comfortable while sweating, and other advances that luckily have replaced the less appealing sports apparel such as the old woolen baseball uniform.(ABSTRACT TRUNCATED AT 400 WORDS)