Many sports use levers--golf clubs, baseball bats, tennis rackets and lacrosse sticks. The use of levers is a key physics lesson, and you can create a science project that helps a student learn how levers affect performance. Some projects include determining the length of a golf club and its relationship to the distance a golf ball will travel. Another is how the string tension on a tennis racket will affect the speed and accuracy of a ball being struck. Another project is to determine how a baseball is affected when it is struck by different areas of a bat.
Gatorade was created based on the science of athletic performance. While most athletes agree that nutrition affects performance, determining why that is true can be an interesting study for athletes. Projects may include time frames of meals prior to performance. The study can have athletes eat the same meal two hours, one hour and a half-hour prior to training and record the effectiveness of each session. A student can also compare the use of sports drinks to water, or compare the nutrition of different energy bars.
Athletes are always looking for a way to train more efficiently. Examining different methods will put an end to locker room myths. A student can review the effects of strength training and the accuracy of baseball pitches, football tosses and free throws. Another study could examine the effects of interval training on stamina by comparing one group that uses parachute training and one that doesn't. A student can also measure the rate of injury compared to flexibility. If the student has enough time, he can take the same group of test subjects and implement stretching programs to see if they reduce injury rates.