Heat Acclimatization and Hydration Status of American Football Players During Initial Summer Workouts
Reference
Yeargan, Susan W., Douglas J. Casa, Lawrence E. Armstrong, Greig Watson, Daniel A. Judelson, Eleni Psathas, and Sarah L. Sparrow. "Heat Acclimatization and Hydration Status of American Football Players During Initial Summer Workouts." Journal of Strength and Conditioning Research 20.3 (2006): n. pag. Web. 26 Oct. 2013.
Purpose of the Study
The purpose of the investigation was to evaluate the new NCAA model of heat acclimatization for Division I football players. We hypothesized that measurements would indicate acclimatization of football players and support the use of the new model.
Methods and Materials
Experimental Approach to the Problem
This observational study of a Division I football team evaluated the new NCAA heat acclimatization guidelines. The players completed a normal practice schedule, allowing researchers to critique heat acclimatization and thermoregulation.We observed the first 8 days, because the majority of heat acclimatization changes and heat illness episodes occur within this time frame. Measures of demographic information including age, weight, and football position provided us with a means of comparisons within the study and with existing literature. Dependent variables reflected commonly used measures of heat acclimatization and factors often observed by medical support staff as a means to ensure safety and to increase performance.
Subjects
A convenience sample of 15 subjects was recruited for the study so as to include a variety of positions, positive attitudes, and no aversion to the temperature sensor. After illness and injury eliminated 4 prospects, 11 healthy student athletes (20 _ 1 year, 1.88 _ 0.05 m, 115.36 _ 18.85 kg, 15.9 _ 8.7% fat, and 32.8 _ 5.1 body mass index [BMI]) from the University of Connecticut football team were included and participated fully in all practices during the study. The following team positions were represented: defensive back, tight end, quarterback, wide receiver, offensive and defensive linemen, and linebacker. The average weight for offensive linemen was 137.94 _ 5.8 kg; linebackers, 104.24 _ 4.05 kg; and tight ends and defensive tackles, 126.55 _ 5.79 kg. The quarterback,
wide receiver, and defensive back average weight was 96.44 _ 9.86 kg. All subjects were either first- or second string players, all receiving significant playing time during practices. Each subject participated in strength and conditioning programs over the summer that were held 4 days a week. The participants were considered to be in good to excellent condition when beginning preseason football. All players attended an orientation regarding the purpose, procedures, risks, and benefits of this investigation, and they provided their informed voluntary consent to participate in accordance with Institutional Review Board standards.
Experimental Design
This field study observed the first 8 days of preseason summer football training camp in August. Days 1–5 and day 7 consisted of 1 practice per day; days 6 and 8 had 2
practices each day. Equipment was gradually phased in over the week; only helmets were worn the first 2 days, helmets and shoulder pads for days 3 and 4, and full pads on days 5–8. The first half of practices comprised individual position drills that consisted of blocking sleds, pass accuracy, route running, and defensive covering. Team drills occurred during the second half of practice and consisted of punt return, tackle drills, and scrimmage. Conditioning, consisting mainly of sprints outside, concluded most practices.
Strength training occurred before or after practices in indoor facilities. As the week progressed, observed intensity increased as equipment was added and more contact
drills were included. Fluid was provided by portable hydration units that were available to players at 10 positions throughout the field so they could be accessed by the players during any down time. Athletic training students also had water bottles to provide players with fluids at any time during practice. Regular breaks were scheduled throughout the practice to give players more time to hydrate as needed. Background information and dietary intake for each subject were obtained prior to preseason camp. Physiological
and perceptual measurements were taken 1 hour prior to, immediately prior to, during, and after each practice. Average times of day for 1 hour prepractice measurements
were 7:06 AM and 1:24 PM. The average time for the first practice measurements in the morning was 7:56 AM and in the afternoon, 2:56 PM. Average times for midpractice measurements were 9:29 AM and 4:23 PM and final practice measurements were at 10:46 AM and 5:37 PM.
Summary of Results/Conclusion
The study found that athlete’s sensitivity to the heat reduced after the first two days of practice. Also, the uniforms reduce heat loss to varying degrees since the fabric can cover more than 50 % of the athlete’s body. Through additions of various equipment throughout practice, thermal strain remained unchanged due to improved thermoregulation through heat acclimatization.
Critique of Study
This study was very interesting to read. I played football in high school and felt cooler with pads on. The data collected in this study supports that the use of equipment in heat has no effect on contributing to athletes overheating. However, throughout the majority of the study, the weather conditions were ideal and athlete’s are in a conditioned state entering practice. I would like to see the study done in more extreme conditions with a randomized sample of people as compared to college athletes.
Practical Application
The new NCAA guidelines are supported by the present study. This study indicates the importance of proper heat acclimatization, appropriate time between practices, the phasing of equipment, and limiting the number of practices. Several variables, such as Ucol, Usg, body weight change, and environmental conditions, can be monitored by personnel to track the progress of players. ESQ scores, heart rate, and core body temperature also may be monitored in high-risk athletes during the first 8 days of summer practices. Coaches, strength and conditioning coaches, and athletic trainers should consider using the aforementioned variables with their own teams to ensure proper hydration and heat acclimatization. Teams at differing levels should refer to the NCAA guidelines (28), evaluate their own preseason procedure, and make appropriate changes so that heat acclimatization occurs to ensure safety and performance of players
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