The Achilles tendon connects the muscles of your lower leg to the heel, and as such it is very important for the proper function of your legs. If you overdo it on the race track or basketball court, you could strain your Achilles tendon and end up with an injury called Achilles tendinitis.
Generally speaking, you can take care of such an injury by following simple advice that can be pursued even at home. However, if your injury is more severe, you will probably benefit from using a special orthotic device or a night splint. Give yourself the support you deserve and opt for a top-quality splint to help you get back on your feet.