The role of the biceps and triceps brachii during tennis serving

Abstract

The purpose of this study was to investigate the role of the biceps and triceps in rapid elbow extension during the ‘slice’ service in tennis. Six serves, performed by a top male county player (21 years) were studied. Simultaneous cine film (200 Hz) and electromyography (EMG) were used to collect the service data. Impact provided a sonic synchronizing trigger, with biceps and triceps data recorded for a 1 s period before and after the trigger point.

Inertia data for the racket were directly determined by a pendulum technique and included in a three segment model of the server's arm. Maximum elbow extension velocities, for the six trials, averaged 44·1, (±3·9) rad7sol;s. Angular velocity values, in the range 24 to 52 rad/s have been reported in tennis and volleyball serving and badminton smashing. Values in excess of 20 rad/s are beyond the contractile velocity range of human skeletal muscle. The contribution of the triceps to rapid forearm extension is therefore questioned. Substantial biceps EMG activity was evident throughout the elbow extension phase, with the peak activity commencing just prior to impact. A powerful stabilizing co-contraction rather than a dominant muscle torque was thus evident at the elbow. Inverse dynamic analysis of the data supported this observation with large resultant internal joint forces, averaging 577 (± 57) N, acting across the elbow joint through impact. The current findings indicate that the triceps activity is more related to elbow stabilization than extension.

Keywords:

• Film analysis
• Muscle activity
• Tennis serve