Key Points
1. Prior to training camp, athletes should be encouraged to undergo strength training and aerobic conditioning to help them begin to acclimatize to warm weather.
2. Sweat rates in athletes such as football players can result in rates of fluid turnover in excess of 10 quarts (~ 10 liters) each day. Substantial losses of sodium and chloride in sweat require adequate fluid and mineral replacement during practice and at meals.
3. The risk of musculoskeletal injuries, heat illness, and upper-respiratory tract infections during training camp can be minimized with adequate rest, proper nutrition, and ample ingestion of fluids before, during, and after training.

Keeping plenty of replacement fluids like Gatorade available for players during breaks is vital to reducing incidents of heat related illness.
INTRODUCTION

Two-a-day practice sessions are often a part of early-season conditioning in American football and year-long training in many other sports. The extra practice time helps accelerate physical conditioning, allows time for strength training and skill development, and helps develop camaraderie among teammates. The very nature of two-a-day practices stresses survival of the fittest. Athletes are frequently placed under additional stress by the heat and humidity that often accompany summer practices. Our expert panel discusses the impact of the high-energy requirements, the limited recovery time, and the psychological stress of “making the cut” during two-a-day training. Strategies based on scientific theory and clinical experiences are presented to help athletes get the most out of two-a-days.
1. What amount of fluid loss can be expected in these athletes?
Walters: In my experience in the college setting, it is common for a football player to lose over 12 pounds during practice-even when we go to tremendous efforts to force fluids on these guys. Studies report as much as 24 pounds of fluid loss (about 11 kg) in a 24-hr period. Regarding fluids and electrolytes, we know these are vital to bodily functions. Players simply can’t practice effectively without proper levels. When the body’s fluid level drops, the body can not adequately cool itself or perform normal metabolic functions that support physical activity.
2. What strategies do you recommend to maintain energy intake and lean body mass during two-a-days?
Walters: During the two-a-day routine, athletes have to be diligent in maintaining hydration status. Furthermore, they must understand that losing body weight during practice comes from fluid, not fat! By maintaining proper hydration, we can prevent much of the problems associated with heat-related illnesses. We require athletes to weigh in before and after each practice-in their shorts only. During the first practice of each week, the athlete’s weight is recorded. From this, we determine the athlete can leave the training room and for allowing participation in subsequent practice sessions. After a practice, the players must attain a body weight within 4% of their “certified” weight before they can leave the training room. Before they can participate in the next session, their weight must be within 2% of the “certified” weight. We give our players Sundays off, and this day of rest allows them a chance to rehydrate-and establish a new weight to be certified on Monday.
3. What tips can you offer to athletes preparing for two-a-day sessions?
Walters: I don’t believe there is any replacement for athletes being in top shape. I see fewer injuries in those teams that are in good shape-and further, when injuries do occur, well-conditioned athletes seem to be able to return to play more quickly. Further, acclimatization, or being accustomed to the environment, has to be accomplished. Other ways we combat the risk of heat-related illness is with good nutritional habits. Maintaining fluid balance is also critical. We monitor pre- and post-practice weights and chart weight loss so that we can accurately advise athletes on their fluid intake. Finally, adequate rest must be accomplished. We try to work our athletes hard on the field, but make sure we give them time to rehydrate, cool down, and relax. We also make sure to have several hours of rest between practices to allow for adequate recuperation.

Getting Gatorade on the field and into the players during timeouts can give your players a competitive edge.
Here are some additional tips on ways to make two a day football practices, in the heat of the summer, safe and productive. These tips were provided through Gatorade’s Sports Science Series, a series that Dr. Walters was a big part of during his days working in college athletics.

Stay Cool
• Get in shape and acclimate.
• Know the warning signs of dehydration and heat illness.
• Don’t rely on thirst to drink.
• Drink on schedule.
• Favor sports drinks.
• Monitor body weight.
• Watch urine color and volume.
• Shun alcohol and caffeine.
• Key on meals.
• Stay cool when you can.
From: Eichner, E.R. (1998).
Treatment of Suspected Heat Illness.
Int. J. Sports Med. 19:S150-S153

Athletic Trainers have a crucial role in maintaining the hydration level of players in practice activities as well as on game day.
Stay Healthy
• Minimize the stresses of life.
• Eat a well-balanced diet.
• Avoid over-training.
• Sleep well.
• Avoid rapid weight loss.
• Avoid sick people and large crowds.
• Keep hands away from nose and mouth.
• Get a flu shot.
• Key on meals.
• Stay hydrated and ingest carbohydrates during exercise.
From: Niemen, D.C. (1998).
Immunity in Athletes: Current Issues
Sports Science Exchange 11(2): 1-6

Stay Hydrated
• Drink throughout the day (water, sports drinks, fruit juice, non-caffeinated soft drinks).
• Drink at least 16 oz. two hours before a practice or game (to allow time to urinate).
• Drink another 8 oz. 15 minutes before exercise (to help insure immediate hydration).
• Drink to fully replace sweat loss during exercise (at least 4 to 8 oz. every 15 minutes).
• Drink 24 oz. for every 1 lb. Of body weight deficit after exercise.
From: American College of Sports Medicine (1996).
Exercise and Fluid Replacement.
Med Sci. Sports Exercise 28(I): I-iiv.

The following post references the practices I recommended during my tenure as the Head Athletic Trainer at the University of South Carolina. The University is in the midst of the heat belt of southeastern United States, and aggressive strategies had to be embraced to keep our student-athletes safe.