The interaction of body armor, low-intensity exercise, and hot-humid conditions on physiological strain and cognitive function.

OBJECTIVE This project was aimed at evaluating the impact of combat armor on physiological and cognitive functions during low-intensity exercise in hot-humid conditions (36 degrees C and 60% relative humidity). METHODS Nine males participated in three trials (2.5 hours), walking at two speeds and wearing different protective equipment: control (combat uniform and cloth hat); torso armor with uniform and cloth hat; and full armor (uniform, torso armor, and helmet). RESULTS As time progressed, core temperatures increased and deviated significantly among trials, rising at 0.37 degrees C h(-1) (control), 0.41 degrees C h(-1) (torso armor), and 0.51 degrees C h(-1) (full armor). Heart rates also progressively diverged, and subjects lost significantly more sweat during the two armored trials. However, cognitive-function tests revealed neither significant main effects nor time by treatment interactions. CONCLUSION The combat armor and helmet significantly increased thermal and cardiovascular strain, but these were unlikely to lead to either exertional heat illness or impaired cognitive function during uneventful urban, military patrols in hot-humid conditions.