Perceptual Responses While Wearing an American Football Uniform in the Heat

Abstract

Context:The protective equipment worn during American football has been shown to increase thermal strain; however, the perception of this increased heat has not been examined.Objective: To evaluate perceptual responses of American football players while wearing different uniforms during exercise in the heat and to evaluate how these responses may be used to monitor athlete safety.Design: Randomized controlled trial. Setting: Human Performance Laboratory.Patients or Other Participants: Ten men with more than 3 years of competitive experience as football linemen (age 5 23.8 6 1.3 years, height 5 183.9 6 1.8 cm, mass 5 117.4 6 3.5 kg, body fat 5 30.1% 6 1.7%) participated.Intervention(s): On 3 occasions in hot, humid (336C, 48%-49% relative humidity) environmental conditions, participants completed 10 minutes of strenuous repetitive box lifting (RBL), 10 minutes of seated rest, and up to 60 minutes of treadmill walking. At each trial, they wore a different uniform condition: control (CON) clothing comprising shorts, socks, and sneakers; partial (PART) National Football League (NFL) uniform comprising the uniform without helmet or shoulder pads; or full (FULL) NFL uniform. Exercise, meals, and hydration status were controlled.Main Outcome Measure(s): Rectal temperature (T re ), skin temperature (T sk ), rating of perceived exertion (RPE), thermal perception (THM), perception of thirst (TST), and perception of muscle pain (MPN) were obtained for time points matched across trials. Results:Nineteen of the 30 trials ended before 60 minutes of treadmill walking as a result of participant exhaustion. Mean treadmill time was longer for the CON condition (51.7 6 13.4 minutes) than for the PART (43.1 6 15.6 minutes; t 9 5 3.092, P 5 .01) or the FULL (36.2 6 13.2 minutes; t 9 5 4.393, P 5 .002) conditions. Neck and forearm T sk increased between the initial time point and the end of exercise in the PART (33.6 6 0.96C and 35.0 6 0.66C, respectively; F 2,18 5 9.034, P , .001) and the FULL (33.4 6 0.96C and 35.2 6 0.66C, respectively; F 2,18 5 21.011, P 5 .002) conditions. Rate of T re rise was greater in the FULL (0.042 6 0.0106C/min) than in the PART (0.034 6 0.0066C/min) condition (F 2,27 5 10.69, P 5 .04). We found a relationship at the post-RBL and final time points between RPE and THM (r 5 0.75, P , .001 and r 5 0.59, P , .001, respectively), RPE and TST (r 5 0.76, P , .001 and r 5 0.61, P , .001, respectively), and RPE and MPN (r 5 0.63, P , .001 and r 5 0.64, P , .001, respectively). The RPE was greater at the end of exercise in the PART (17 6 2) and FULL (18 6 1) conditions than in the CON (15 6 3) condition (F 2,18 5 7.403, P 5 .005).Conclusions: Although no differences in perceptual scales existed between the PART and FULL conditions, the T sk and rate of T re increase differed, indicating that football athletes find it difficult to perceptually rate exercise conditions as potentially dangerous hyperthermia develops. In addition, correlations between the perceptual scales further defined perceptual responses during ex...

Sprint performance under heat stress: A review

“…Wearing protective clothing, for instance, as American footballers do, decreases the effectiveness of heat loss mechanisms (Sawka et al., ). The addition of a uniform exaggerates perceptual ratings, skin and core temperatures at a given workload, and decreases the amount of exercise an individual can safely perform (Johnson et al., ). While this microclimate may predispose to exertional heat illness, particularly if a competition is played with a high level of heat stress, the impact of protective clothing on repeated short‐term power production remains under researched (Havenith et al., ).…”

Heat Stress During American Football

“…Prior research examining the effect of protective equipment, body mass size, and player position has found that American football athletes exercising in hot and humid environmental conditions with full protective equipment were more likely to experience uncompensable heat stress, an earlier onset of fatigue and exaggerated perception of effort [35,44]. Furthermore, athletes with a greater body mass, particularly linemen, are at greater risk of exertional heat illness that results from a combination of greater metabolic heat production and reduction of convective heat losses [8,9].…”

Heat Stroke in Physical Activity and Sports (Original version in English)

“…In sports with protective equipment, such as American football and lacrosse, the barriers created by the equipment could hinder body heat loss from evaporation, conduction, convection, and radiation (Johnson et al, 2010). These barriers could also trap the heat between the skin and the equipment and clothing, creating a hot-humid microenvironment, which hinders the ability to dissipate heat.…”