American football athletes are at the highest risk of developing exertional heat illness (EHI). We investigated whether percooling (i.e., cooling during exercise) garments affected perceptual or physiological variables in individuals exercising in the heat while wearing football uniforms. Twelve males (age=24+/-4y, mass=80.1+/-8.5kg, height=182.5+/-10.4cm) completed this cross-over, counterbalanced study. On day 1, we measured peak oxygen consumption (V[Combining Dot Above]O2). On days 2 and 3, participants wore percooling garments with (ICE) or without (CON) ice packs over the femoral and brachial arteries. They donned a football uniform and completed three, 20-minute bouts of treadmill exercise at ~50% of peak V[Combining Dot Above]O2 (~33[degrees]C, ~42% relative humidity) followed by a 10-minute rest period. Ice packs were replaced every 20 minutes. Rating of perceived exertion (RPE), thermal sensation, and thirst sensation were measured before and after each exercise bout. Environmental symptom questionnaire (ESQ) responses and urine specific gravity (Usg) were measured pre-testing and after the last exercise bout. V[Combining Dot Above]O2, change in heart rate ([DELTA]HR), and change in rectal temperature ([DELTA]Trec) were measured every 5 minutes. Sweat rate, sweat volume, and percent hypohydration were calculated. No interactions (F17,187<=1.6, P>=0.1) or main effect of cooling condition (F1,11<=1.4, P>=0.26) occurred for [DELTA]Trec, [DELTA]HR, thermal sensation, thirst, RPE, ESQ, or Usg. No differences between conditions occurred for sweat volume, sweat rate, or percent hypohydration (t11<=0.7, P>=0.25). V[Combining Dot Above]O2 differed between conditions over time (F15,165=3.3, P<0.001); ICE was lower than CON at 30, 55, and 70 minutes (P<0.05). It is unlikely these garments would prevent EHI or minimize dehydration in football athletes.
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