Learn where to find sporting programs for children. Public Schooled Kids get fliers sent home about every little league, bmx competition and junior tennis event in town, but home schooled kids don't. So your first task is to find the leagues, teams and sporting resources in your area.
Collect a list of phone numbers, maybe from the yellow pages, for various sporting goods stores, equipment suppliers and sports leagues. These groups aren't often highly visible because they are run by volunteers and not for profit, so they don't often advertise.
Keep track of the information you receive about sign-ups and registration processes. You might be instructed to call back in a few months, or to call a different person. Keeping the information on a spreadsheet or other document makes it easy to share.
Contact your local sporting goods stores, too. In many areas, the sign-ups are at the sporting goods store. If they don't know when sign-ups are, they might know who is in charge. If you offer to be the liaison or contact person for the homeschooling community in your area, you are likely to be contacted whenever sign-ups are going on.
Ask your local home school support group members if any of them are participating in sports programs. If they are, then they can help you find out when the sign-ups are again.
Consider starting your own team. These teams usually practice after school hours and play games very early on weekend mornings. With a team full of home schoolers, you can plan to have daytime practices leaving your evenings free for family time.
Try a sport that isn't team-focused. Skateboarding is a popular sport. Many home schooled kids love to skateboard, skateboarding can be practiced alone and it also ingrains a sense of physics in reality for many children. Imagine--science from skateboarding. There's friction, centrifugal force, angles and inclines and of course, gravity.