Some pronation is normal and helps absorb shock, but excessive pronation can cause overuse injuries. A drill in which you swim using only your arms. Raising your head while swimming to find a landmark so you can remain on course in open water. Typically caused by hitting a curb or rock. Rolling to the outside of the foot when running.
Excessive supination can strain ligaments, tendons and bones.
Without dryland training of the stabilizing muscles, this condition can lead to tendinitis. Someone who takes the sport a bit too seriously. An indoor trainer for cycling. The bike is mounted on a stand that holds the rear wheel. When you pedal, the rear wheel turns a fan that provides resistance.