It has been shown time and time again that participation in athletics by high school students actually increases academic performance as it teaches responsibility and gives an incentive for students to keep their athletic eligibility. Furthermore, it teaches many students that college is an option and gives yet another incentive for athletes to do well in classes.
It is documented in medical journals that people who are healthier and fitter are more productive and at both work and in education. This idea that health and academics are not related is a false and needs to be culturally change in the United States. If a person is healthy they will be more productive in their daily lives.
I do not believe participation in athletics in high school boosts academic performances. I believe students will perform the same regardless of their athletic participation. Some students may be interested in athletics and others may not be. There are some students who will take a great deal of interest in athletics, but perform poorly in class. Each person is different, there's no one solution to guarantee academic performance and even if there was, it wouldn't be through athletics.
Participation in athletics in high school does not boost academic performance. Spending time on sports only serves to increase athletic ability. If a student needs to perform better in school then they need to study harder and longer. They should also get out of any athletics other than those needed for basic exercise.