Asymmetrical loading of the human triceps surae: I. Mediolateral force differences in the Achilles tendon

An in vitro experiment was designed to identify whether tensile force on di fferent triceps surae components would result in nonhomogenous force distri bution across the human Achilles tendon. Medial tendon forces were signific antly higher than lateral (23.2 +/- 6.6%; P less than or equal to 0.05) whe n only the gastrocnemius medialis was subjected to force. Lateral forces we re significantly higher when both gastrocnemii (30.6 +/- 16.5%) or all thre e muscles (20.7 +/- 10.9%) were loaded. Experimental identification of forc e concentrations in the human Achilles tendon contributes to the understand ing of the origin of its injury.