Hamstrings, the muscles in the back of the thigh, are very important for effective sprinting and powerful running strides on the tennis court. They bend the leg in the knee and straighten at the hip joint. Hamstring injury is a common occurrence in tennis. There are many reasons: insufficient flexibility, poor strength (especially in comparison to the quadriceps muscles in the front of the thigh), or faulty running mechanics. Our life style with a lot of sitting doesn’t add to the optimal well-being of our hamstrings – they are put in a shortened position and get tight and short even more. For that reason stretching of the hamstrings should be an important part of your tennis fitness and injury prevention regimen.