Stay away from the typical, overdone science fair cliches, instead create something that combines sports and science for your science fair project. 

Some Ideas to Get You Started

• How does the material from which a baseball bat is made affect performance? How does a wood bat compare with an aluminum bat?
• Does altitude affect the height of a ball bounce (for example, a golf ball)? If an effect is seen, can you attribute it to the effect of gravity or atmospheric pressure?
• Examine the effect of energy bars on performance. Pick a sport. Is there a difference in performance if you use a protein-boosting energy bar versus a carbohydrate-boosting energy bar?
• What is the effect of using a corked baseball bat compared with a normal one?
• Does drinking an energy drink (or sports drink) affect reaction time? memory?
• Are there really streaks in baseball? Or is it simply chance?
• Compare energy drinks based on cost, taste, short-term effect, and long-term effect.
• Which sports drink contains the most electrolytes?
• How is ball diameter related to the time it takes the ball to fall?
• Does the length of a golf club affect the distance you can hit the ball?
• Does a swim cap really reduce a swimmer's drag and increase speed?

• How does exercise affect heart rate? This project is especially good if can track data over a longer time frame.
• Does exercise affect reaction time?
• Does regular exercise affect memory?
• At what slope angle is the mechanical advantage of a bicycle lost, as compared with running?
• Compare different brands of balls for a sport (like baseball or golf) for cost versus performance.
• Do helmets really protect against a crash (presumably tested with a stimulant like a watermelon)?
• What is the best air pressure for a soccer ball?
• How does temperature affect the accuracy of a paintball shot?
• Does altitude, temperature, or humidity have an effect on the number of home runs seen at a baseball diamond?
• Does the presence or absence of a net affect free throw accuracy?
• Measure the effect on peripheral vision from wearing different types of corrective eyewear (such as glasses). Does an athlete experience a noticeable improvement when peripheral vision is increased?
• Is there an effect if you fill an inflatable ball with a different gas than air (such as nitrogen or helium)? You can measure height of bounce, weight, effect on passing, and how long it stays inflated.

Tips for Choosing a Sports Science Fair Project

• If you are an athlete or trainer, pick the sport you know best. Can you identify any problems to be examined? A good science fair project answers a question or solves a problem.
• When you have an idea, consider how to design an experiment around it. You need data. Numerical data (numbers and measurements) are better than qualitative data (greater/lesser, better/worse), so design an experiment that gives you data you can graph and analyze.

Do you need more science fair project ideas? Here's a big collection to browse.