Thermal insulation and evaporative resistance of football uniforms

Purpose: To measure the thermal resistance (R_t) and evaporative resistance (R_e.t) of five different configurations of football uniforms commonly worn for American football practices and games. Methods: The R_t (insulation) of the ensembles was measured using an electrically heated manikin in thermal equilibrium with its surroundings. For the R_e.t determinations, the manikin was covered with a cotton knit "skin" and sprayed with distilled water to simulate sweat-saturated skin. Results: Compared with reference values for a T-shirt and shorts ensemble (R_t = 0.140 m²·°C·W^-1, R_e.t = 0.020 m²·kPa^-1·W^-1), the R_t of football uniforms ranged from 0.178 m²·°C·W^-1 (1.15 clo) for a practice configuration of shorts, shoulder pads, practice jersey, and helmet to 0.233 m²·°C·W^-1 (1.50 clo) for a full cold-weather uniform. Associated R_e.t values ranged from 0.027 to 0.039 m²·kPa^-1·W^-1. Conclusion: Football uniforms contribute significantly to the heat load on a player. The thermal and evaporative resistance data presented in this paper can be used in the solution of heat balance equations to predict physiological responses of football players.