A shock-absorbing layer of a training shoe, between the outsole and the insole. It is the heart of the shoe, determining its degree of hardness or softness. Athletes with a heavy footstrike and rigid lower-limb structure, generally benefit from having softer midsoles; those with a lighter more mobile footstrike, benefit from harder midsoles. The midsole must combine two conflicting properties; it must be strong enough to resist the compression and rotational forces produced by the foot striking the ground, and it must be flexible enough to allow the toes to bend during the push-off phase of running and jumping. Midsoles, which do not have these properties, or which lose them through wear and tear, may increase the risk of sports injuries such as stress fractures.
Subjects: Sports and Exercise Medicine.