STUDY FINDS - Common sense tells us that when the body is dehydrated, physical performance declines. Athletes and coaches have long known that even modest fluid loss can hurt endurance and speed. However, research focusing on laboratory mice has uncovered a puzzling exception. The fittest animals actually ran more, not less, when deprived of water for 24 hours.
Researchers at the University of California, Riverside, tested what happens when mice go without water while given free access to running wheels. They used two types of mice. Normal control mice, as well as “High Runner” mice that had been selectively bred for decades to run about three times more than regular mice. When water bottles were removed for 24 hours, both groups lost roughly 20% of their body weight. On the other hand, their exercise responses couldn’t have been more different.