Biomechanics of the head for Olympic boxer punches to the face.

Objective: The biomechanics of the head for punches to the jaw and the risk of head injury from translational and rotational acceleration were studied. Methods: Seven Olympic boxers from five weight classes delivered 18 straight punches to the frangible face of the Hybrid III dummy. Translational and rotational head acceleration, neck responses, and jaw pressure distribution were measured. High speed video recorded each blow and was used to determine punch velocity. Equilibrium was used to determine punch force, energy transfer, and power. Results: Punch force averaged 3427 ( standard deviation (SD) 811) N, hand velocity 9.14 ( SD 2.06) m/s, and effective punch mass 2.9 ( SD 2.0) kg. Punch force was higher for the heavier weight classes, due primarily to a higher effective mass of the punch. Jaw load was 876 ( SD 288) N. The peak translational acceleration was 58 ( SD 13) g, rotational acceleration was 6343 ( SD 1789) rad/s(2), and neck shear was 994 ( SD 318) N. Conclusions: Olympic boxers deliver straight punches with high impact velocity and energy transfer. The severity of the punch increases with weight class.