A comparative study of movement characteristics and neuromuscular responses in tennis one-handed backhand strokes under three self-resistance stroke types.

Objective: The aim of this study was to investigate how different self-resistance strokes influence neuromuscular activation patterns and immediate stroke performance during the one-handed backhand stroke. Methods: Using 3D image analysis system and Noraxon surface electromyography (EMG) system, we quantified movement rhythm, structure, and effectiveness of the three different one-handed backhand strokes performed by 30 male tennis players, as well as the activation sequence and integrated EMG parameters of eight prime movers. We employed one-way analysis of variance (ANOVA) and multiple comparisons to examine differences in the movement characteristics among the three stroke types. Results: 1) No statistically significant differences were detected in the structural kinematic variables among the three strokes. But some differences were observed in the rhythm of the movements, with rotational phase of the stroke being the fastest in the brief self-resistance stroke; 2) In terms of performance outcomes, brief self-resistance stroke exhibited the highest racket head speed and ball speed, prolonged self-resistance stroke had high racket head speed but low ball speed, and free self-resistance stroke had low racket head speed and low ball speed; 3) The sequence of muscle activation was divided into two groups for the free self-resistance stroke and three groups for the stroke. There were no differences among the three strokes in the integrated electromyographic (EMG) values of the prime movers responsible for ball strokes and body rotation; the integrated EMG values of the prime movers involved in physical stroke were higher in the two self-resistance strokes than in the free self-resistance stroke; and the integrated EMG values of the quadriceps muscles were highest in the brief self-resistance stroke. Conclusion: 1) Movement patterns were similar among strokes, while brief self-resistance stroke showed faster body rotation and improved stroke performance. 2) Brief self-resistance stroke achieved faster rotational execution and superior stroke performance, which may be associated with greater cumulative neuromuscular activity. Further studies using time-normalized EMG and kinetic measurements are needed to clarify the underlying mechanisms. 3) Brief self-resistance strokes showed faster rotational execution and higher acute stroke performance, which may be associated with altered neuromuscular activation patterns.