HEAT STRESS AND EXHAUSTION COMPOUNDED BY FOOTBALL UNIFORMS

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When football players train and compete in hot conditions, heat stroke is always a risk, and treatment delays can be fatal. Although 20 heat stroke deaths occurred during high school and collegiate practices between 2000 and 20071, until recently human responses to wearing a football uniform while exercising had only been sparsely investigated.



Two new studies published this month in the Journal of Athletic Training, the scientific publication of the National Athletic Trainers’ Association, help shed light on the role that American football uniforms play in football players’ perception of heat stress and heat exhaustion. March is National Athletic Training Month with the theme “Sports Safety is a Team Effort.”



Both studies, based on research conducted at the University of Connecticut, reveal greater strain on players wearing either a full NFL uniform, or partial uniforms without helmets and shoulder pads. In addition, football players find it difficult to determine on their own if and when potentially dangerous body temperature increases develop, which means greater vigilance by coaches, athletic trainers and others on the sidelines is required to ensure athletes are playing safely.



In a study titled, “The American Football Uniform: Uncompensable Heat Stress and Hyperthermic Exhaustion,” football players completed three controlled trials in a hot environment (33C, 48 percent to 49 percent relative humidity) wearing a full or partial NFL uniform, or a control condition wearing shorts, socks, sneakers and a T-shirt. Researchers concluded that wearing a full or partial uniform resulted in greater strain on a player’s body – including higher body temperature, abnormally low blood pressure and early exhaustion during heat stress -- than they did during the control condition. These findings support previous recommendations calling for limiting use of helmets and shoulder pads during the initial days of summer workouts, in order to reduce the risk of heat illness.



1 National Center for Catastrophic Sport Injury Research


“Considering every athlete’s need for ample time to acclimatize in the heat, there is no justification for wearing protective equipment during the initial three to five days of summer football workouts, when the highest incidence of heat stroke and heat exhaustion occurs,” said one of the study’s authors Brendon P. McDermott, PhD, ATC, athletic trainer and assistant professor in the graduate athletic training program in the department of health and human performance at the University of Tennessee at Chattanooga.



McDermott offers the following tips for safe football participation in the heat:




1. All coaches, parents and athletes should be properly educated on basic prevention, recognition and treatment of exertional heat illnesses.

2. No athletic practice should last more than 3 hours in the heat.

3. No “double-session” practices should occur in the first 5 days of activity.

4. Practices should be separated by at least 3 hours and proper sleep should be attained between consecutive days of activity.

5. Rest break length and frequency should be scheduled and adhered to, based on environmental conditions and exercise intensity.

6. An athletic trainer should be on site before, during and after all practices to ensure proper prevention, recognition and treatment of suspected injury or illness.

7. Remove protective equipment during rest breaks for at least 10 minutes.

8. Remove extra clothing and protective equipment during intense conditioning drills (sprints, etc.)

9. Do not moisten uniform or equipment on purpose.





In the second report, “Perceptual Responses While Wearing an American Football Uniform in the Heat,” participants completed 10 minutes of seated rest and up to 60 minutes of treadmill walking on three occasions: once wearing full uniforms, once wearing partial uniforms and once wearing control clothing (shorts, socks, sneakers and a T-shirt).



When athletes wore full and partial uniforms, they perceived no differences in their body conditions, even when their body temperature increased. These findings indicate that football players find it difficult to perceptually rate their own exercise conditions, even as potentially dangerous hyperthermia develops. The report counsels that these findings be considered by coaches who design practices, particularly if players are not heat acclimatized, or if they are unfit in the early season when most heat illnesses occur.



“Although football uniforms, including shoulder pads and helmets, protect players from impact, they also trap body heat, increasing the risk of heat illness secondary to cardiovascular strain and hyperthermia,” said McDermott, who was also an author of the second study. “The addition of a football uniform with or without pads increases body and skin temperature, but does not increase perceived stress at a given workload and decreases the amount of exercise an individual can safely perform. The athletic training staff and coaches, as in the first study, must be highly attentive to this, because an athlete may not be aware that he is experiencing a life-threatening rise in body temperature.”



To read both Journal of Athletic Training articles in their entirety, visit:
http://www.journalofathletictraining.org/doi/pdf/10.4085/1062-6050-45.2.117

http://www.journalofathletictraining.org/doi/pdf/10.4085/1062-6050-45.2.107