Strenuous training, often while wearing heavy padding or equipment, is common to many sports and to athletes of all ages and skill levels. Depending on the temperature, humidity and overall conditioning, an athlete engaged in vigorous exercise can lose over 3 liters of fluid in sweat losses in an hour. If such losses exceed fluid intake; progressive acute dehydration results.
Beyond health and safety, studies that explore the effects of water deficit on athletes show that even mild dehydration can result in a significant deterioration in athletic performance. In 2006, researchers at Penn State University and the Gatorade Sports Science Institute working with professional basketball players reported a 6% decrease in shooting percentage and a 7% deterioration in sprint times at dehydration levels of just 2% loss of body mass - barely above the sensation threshold of thirst. The researchers further noted from earlier work that the majority of elite athletes involved in stop-and-go sports such as basketball, football and soccer show up to practice and games already at or exceeding this level of dehydration.
Additional studies have noted a decrease in physical work capacity at levels of dehydration even less than 2% loss of body mass during intense exercise in the heat.
The health and safety benefits of managing hydration are well understood by the athlete community, as are the performance advantages in competition. Athletes simply perform better, and recover more quickly, when they are properly hydrated. Athletes, Trainers and Coaches all therefore seek to establish and maintain optimal hydration thresholds, not only to ensure health and safety, but to maximize competitive advantage.