Swimming (sport) less stress on joints. Due to continuous rotation and usage, the shoulder (rotator cuff) is the joint most susceptible to injury in swimmers. As opposed to a single incident, injury to the rotator cuff in swimmers is a result of repeated trauma and overuse. The joint is most prone to injury when the arm is repetitively used in a position above the horizontal. This position occurs in each of the four swimming strokes in every cycle of the arms. Of the four muscles and tendons of the rotator cuff, the injury, or tear, is most likely to occur in the
Synovial sheath Synovial sheath A synovial sheath is one of the two membranes of a tendon sheath which covers a tendon. The other membrane is the outer fibrous tendon sheath. The tendon invaginates the synovial sheath from one side so that the tendon is suspended from the membrane by the mesotendon, through which the blood vessels reach the tendon, in places where the range of movement is extensive. The mesotendon disappears or remains in the form of narrow tendinous bands as threads known as vincula tendina. The synovial sheath is found where the tendon passes under ligaments and through osseofibrous tunnels; their