Repeated strong contraction and relaxation of muscles during exercise can cause tension in the muscle tendon unit. The physical stress caused by tension on muscle tissue is closely linked to pain. This study evaluated sex differences in pain after stretching of hamstring muscles and the decrease in pain over time.

Hamstring flexibility was measured with an active knee extension test before and after stretching. Pain was measured using the visual analogue scale immediately after stretching, on day 1, and day 2.

Pain reported by men was higher than that reported by women, but the difference was not significant. The pain reported by both men and women was significantly decreased on day 1, with a smaller decrease on day 2. There was no correlation between the increase in flexibility and pain.

Pain did not differ between men and women. Additionally, pain was not simply determined by intensity of stretching. Individual characteristics and other factors must also be considered.