Necessity of Removing American Football Uniforms From Humans With Hyperthermia Before Cold-Water Immersion

Context: The National Athletic Trainers' Association and the American College of Sports Medicine have recommended removing American football uniforms from athletes with exertional heat stroke before cold-water immersion (CWI) based on the assumption that the uniform impedes rectal temperature (T-rec) cooling. Few experimental data exist to verify or disprove this assumption and the recommendations. Objectives: To compare CWI durations, T-rec cooling rates, thermal sensation, intensity of environmental symptoms, and onset of shivering when hyperthermic participants wore football uniforms during CWI or removed the uniforms immediately before CWI. Design: Crossover study. Setting: Laboratory. Patients or Other Participants: Eighteen hydrated, physically active men (age = 22 +/- 2 years, height = 182.5 +/- 6.1 cm, mass = 85.4 +/- 13.4 kg, body fat = 11% +/- 5%, body surface area = 2.1 +/- 0.2 m(2)) volunteered. Intervention(s): On 2 days, participants exercised in the heat (approximately 40 degrees C, approximately 40% relative humidity) while wearing a full American football uniform (shoes; crew socks; undergarments; shorts; game pants; undershirt; shoulder pads; jersey; helmet; and padding over the thighs, knees, hips, and tailbone [PADS]) until T-rec reached 39.5 degrees C. Next, participants immersed themselves in water that was approximately 10 degrees C while wearing either undergarments, shorts, and crew socks (NOpads) or PADS without shoes until T-rec reached 38 degrees C. Main Outcome Measure(s): The CWI duration (minutes) and T-rec cooling rates (degrees C/min). Results: Participants had similar exercise times (NOpads = 40.8 +/- 4.9 minutes, PADS = 43.2 +/- 4.1 minutes; t(17) = 2.0, P = .10), hypohydration levels (NOpads = 1.5% +/- 0.3%, PADS = 1.6% +/- 0.4%; t(17) = 1.3, P = .22), and thermal-sensation ratings (NOpads = 7.2 +/- 0.3, PADS = 7.1 +/- 0.5; P > .05) before CWI. The CWI duration (median [interquartile range]; NOpads = 6.0 [5.4] minutes, PADS = 7.3 [9.8] minutes; z = 2.3, P = .01) and T-rec cooling rates (NOpads = 0.28 degrees C/min +/- 0.14 degrees C/min, PADS = 0.21 degrees C/min +/- 0.11 degrees C/min; t(17) = 2.2, P = .02) differed between uniform conditions. Conclusions: Whereas participants cooled faster in NOpads, we still considered the PADS cooling rate to be acceptable (ie, >0.16 degrees C/min). Therefore, if clinicians experience difficulty removing PADS or CWI treatment is delayed, they may immerse fully equipped hyperthermic football players in CWI and maintain acceptable T-rec cooling rates. Otherwise, PADS should be removed preimmersion to ensure faster body core temperature cooling.