The term ‘calf muscle’ is collective for a group of three muscles in the lower leg – Gastrocnemius, Soleus and Plantaris – all of which share a joint Achilles tendon that inserts onto the heel bone (calcaneus). Calf muscle strains are usually the result of a sudden acceleration force or eccentric overstretch, i.e. when a sportsperson lunges forward when playing tennis, or runs onto a kerb and the heel drops suddenly. They predominantly occur in the medial (inner side) Gastroc