Option 1: Give up early and find another topic
Generally, the biggest problem with every sports-themed project is the lack of standardization of some part of the procedure (see “fatal flaws” page). There is just NO WAY to make sure that you, as the experimenter, hit the baseball, kick the soccer ball, throw the football, jump the hurdle, catch the pass, run the course, etc., the same exact way each time. That means that there will be BOTH (1) changes in your activity (i.e. part of your procedure) AND (2) changes in the independent variable that you are trying to evaluate, so consequently, you will not be able to claim that differences in the outcome (dependent variable) are related to the independent variable.
In other words, you will not be able to claim that your experiment shows that metal bats hit baseballs further than wooden bats do because I will be able to claim you didn’t control for differences in the strength of your swing or the speed of the pitch.
Option 2: Find a way to standardize the procedure
If you can solve the problem described in option 1, you should be rewarded for creativity and a properly executed experiment. For pitching, you could use a pitching machine. That means you could answer questions like:
How does the density of the baseball (or size of the ball, or brand of ball, or defects in the ball) affect the speed (or accuracy, or distance, or anything measurable) of the pitch?
In this example, you will be changing one aspect of the baseball (independent variable) and measuring one aspect of the pitch (dependent variable) AND your procedure (pitching machine vs. arm) is standardized.
WARNING: This option might require you to build a contraption that does part of the procedure for you (i.e., ball kicking, tennis racquet swinging, football launching, etc.). However, you can’t stop there (see gadgeteering under fatal flaws). For a successful project, you will need to use your contraption to answer a question.
Option 3. Use online statistics to answer a question
This one is risky and I recommend you run this by your teacher because it is science, but not a science experiment, per se.
FYI: This would make an excellent math fair project.
First look for statistics that are available online. For example, when I googled “online sports statistics” I found http://www.bballsports.com/ as the top link. Here they have all sorts of data already compiled for you. Identify the readily available statistics for your favorite sport, or team, or college, etc.
Second think of relationships that interest you. For example:
Question: Do baseball players hit more home runs when they get up to bat more often?
Experiment: Compare the number of at-bats (independent) to the number of home runs (dependent) for all players for one season (or some other, very well defined interval). What does the scatter plot look like?
Question: Are taller basketball players called for more fouls?
Experiment: Graph player height vs. number of fouls per time played (scatter plot)
WARNING: The misconception that “statistics lie” or that “you can make statistics say anything” results from the lack of definition of the group you are studying. The key to your project will be to define that group BEFORE you graph the 2 variables of interest.
WARNING: Make sure you understand the difference between CORRELATION and CAUSATION as this will come up in the judging evaluation and will affect the way you state your conclusions.
WARNING: This type of project is fairly quick, so you may want to include several questions to increase the depth of the investigation. For example, you could ask an interesting question as it applies to your favorite team, and then repeat it for other teams to see if the relationship holds. Similarly you can ask the question as it applies to a certain time period (e.g. a season) and then repeat to see if it holds for all seasons, or all sports, or all colleges, etc.