The effect of a flexed elbow on bowling speed in cricket

The laws of bowling in cricket state 'a ball is fairly delivered in respect of the arm if, once the bowler's arm has reached the level of the shoulder in the delivery swing, the elbow joint is not straightened partially or completely from that point until the ball has left the hand'. Recently two prominent bowlers, under suspicion for transgressing this law, suggested that they are not 'throwing' but due to an elbow deformity are forced to bowl with a bent bowling arm. This study examined whether such bowlers can produce an additional contribution to wrist/ball release speed by internal rotation of the upper arm. The kinematics of a bowling arm were calculated using a simple two-link model (upper arm and forearm). Using reported internal rotation speeds of the upper arm from baseball and waterpolo, and bowling arm kinematics from cricket, the change in wrist speed was calculated as a function of effective arm length, and wrist distance from the internal rotation axis. A significant increase in wrist speed was noted. This suggests that bowlers who can maintain a fixed elbow flexion during delivery can produce distinctly greater wrist/ball speeds by using upper arm internal rotation.