The role of the non-playing hand during topspin forehand in table tennis

Theoretical tutorials and the scientific literature do not provide information on the proper use of the non-playing hand in table tennis. This study aimed to evaluate the course of the movement in the joints of the non-playing limb during a table tennis topspin forehand stroke (played after a backspin ball) and to determine the inter-individual movement variability. The study involved 12 male table tennis players (178.7 ± 5.5 cm, 70.0 ± 6.6 kg, 23 ± 3 y) at a competitive level. The participants performed one topspin forehand as a response to a backspin ball. Kinematics were measured using an Inertial Motion Unit–MR3 myoMuscle Master Edition system. Changes in the angles of the upper limb joints (with particular emphasis on the non-playing hand) during the forehand topspin were analyzed. A novel method of normalized function of variance was used to characterize areas of high/low variability of movement. Most of the movements in the joints of the non-playing limb were performed symmetrically to the playing one, especially in the hitting phase. A rapid change of direction characterizes these movements, just before or during the hitting phase, which may indicate a supportive, ‘driving’ character for these movements. High inter-individual variability for the duration of the entire movement cycle in both limbs was observed; higher in the non-playing limb. This perhaps indicates a greater degree of individualization on the non-playing side.