The hamstrings are the group of muscles on the back of your thigh. There are 3 on each leg and they travel downwards from the pelvis to just below the knee. Their primary functions are bending the knee and extending the leg behind you. Commonly these are caused by overstraining or overstretching, and frequently occur in sports where there is sprinting involved such as football, athletics and rugby.
The aim of treatment initially is to minimise pain and restore movement before progressing to strengthening and rehabilitation exercises.