The hamstring comprises most of the muscle bulk in the back of the thigh. It is important for pushing off, jumping and landing and particularly when riding for ensuring good contact to the saddle. The hamstring is made up of three muscles – the biceps femoris, the semitendinosus and the semimembranosus, each with a common proximal attachment via a large tendon to the ischial tuberosity of the pelvis (the large bone you sits on in the buttock).
The most common cause of groin pain is a muscle, tendon or ligament strain, particularly in athletes who play stop and go sports. Groin pain might occur immediately after an injury, or pain may come on gradually over a period of weeks or even months and will be worsened by continued use of the injured area. Less commonly, a bone injury or fracture, a hernia or even kidney stones might cause groin pain. Although testicle pain and groin pain are different, a testicle condition can sometimes cause pain that spreads to the groin area.