Very few things can make a child feel more isolated or "othered" than not being able to participate in sports or extracurricular activities because of a disability. Both the IDEA (educational law) and Section 504 (civil rights-based law) require districts to provide students with an equal opportunity to participate in extracurricular activities and nonacademic services. The federal regulations require the IEP to include any supplementary aids and services that the student will need to participate in an activity, if the students wants to participate. The goal of including it in the IEP is to ensure meaningful access. This can be done by being aware of your child's class scheduling, the necessary accommodations, or even state athletic eligibility rules.
I discussed a case in my book, Brown v. Elk Grove Unified School District, where a student with Emotional Disturbance was denied a position on the basketball team because of his emotional outbursts, even though, athletically, he was one of the best players. The court would not dismiss the case. Instead, the court found the school denied the student meaningful access by not investigating his claims of being denied a spot on the team and also not making any attempts to provide accommodations.
The key is meaningful access and the law requires children with disabilities to have access to the same benefits (educational or otherwise) as a non-disabled student.