A comparison of wrist angular kinematics and forearm EMG data for an elite, intermediate and novice standard tennis player performing a one-handed backhand groundstroke

Wrist angular kinematics (flexion/extension) and electromyography (EMG) data of a one-handed tennis backhand groundstroke were compared for an elite, intermediate and novice standard tennis player. For this purpose, synchronisation of the data with respect to ball impact time was achieved by a system of wireless and wired triggers and receivers. All three players maintained wrist extension for the 0.6 second period centred on ball impact. The elite and intermediate player struck the ball with the wrist extended by an average of 10o from neutral alignment whilst moving towards flexion. After ball impact the wrist moved back towards and further into extension. The novice player was characterised by fluctuations in the wrist flexion/extension angle prior to ball impact with the wrist extended on average by 30o from neutral alignment at impact. The wrist of the novice palyer moved back towards and further into extension after ball impact, although less than for intermediate and elite players. For the elite player, peak EMG levels for the wrist flexors and extensors were reached consistently 0.05-0.1 seconds prior to ball impact. Wrist flexor EMG levels for the intermediate and novice players peaked on average 0.02 seconds after ball impact and extensor EMG levels peaked at ball impact. For the novice player, both flexor and extensor EMG data exhibited fluctuations consistent with the wrist kinematics data. Previously cited conditions that predispose a novice player to injury were not observed in this study. Given current injury mechanism theories, the data from this study suggests that the susceptibility of a player to tennis elbow injury cannot be established by generic skill level alone. Tennis players need to analysed as individuals.