There are numerous muscles in the upper leg that work to bend and straighten the knee and hip. In addition to this there are adductor muscles on the inside of the leg which bring the thigh back to a central position, these muscles are more commonly known as the groin muscles. During sport and exercise these muscles are put under considerable stress and can become damaged. In addition to resting the injured muscle many athletes use compression shorts to help with their rehabilitation. Compression can help with blood flow to the affected area and increase the speed at which any swelling is reduced and aid in the muscle repairing itself.