Optimizing tennis serve performance in university players through 2D kinematic motion analysis and biomechanical feedback

Tennis serve performance depends on the coordinated execution of multiple body segments and the timing of successive serve phases. Although biomechanical feedback has been used to support technical refinement, its immediate effects on university-level players remain insufficiently understood. This study examined whether two-dimensional (2D) kinematic analysis combined with structured visual and verbal feedback was associated with measurable immediate changes in selected serve mechanics and performance outcomes. Sixty male university tennis players aged 18–24 years were allocated to experimental and control groups ( n = 30 each) in a quasi-experimental pretest–posttest design. The experimental group received one session of combined video-based and verbal biomechanical feedback, whereas the control group continued conventional training. Serves were recorded using calibrated 2D motion analysis software (Dartfish; RMS error < 1%) to assess temporal, ball-toss, kinematic, racket, and performance variables. Pre–post change scores were compared between groups using independent-samples t-tests or Mann–Whitney U tests, with within-group analyses conducted using paired-samples t-tests or Wilcoxon signed-rank tests. Effect sizes and percentage changes were also calculated. Compared with the control group, the experimental group showed greater immediate changes in total serve time ( p = 0.030, d = 0.56), forward swing time ( p = 0.012, d = 0.72), toss height ( p = 0.021, d = 0.60), horizontal toss deviation ( p = 0.003, r = 0.65), knee flexion ( p = 0.015, d = 0.61), hip extension ( p = 0.004, d = 0.86), trunk extension ( p = 0.006, d = 0.84), trunk forward flexion ( p = 0.011, d = 0.73), shoulder abduction ( p = 0.002, d = 1.02), wrist extension ( p = 0.003, d = 0.98), estimated planar racket velocity ( p = 0.001, d = 1.10), and ball impact height ( p = 0.015, d = 0.59). No statistically significant pre–post changes were found in the control group for the corresponding variables. Serve accuracy increased from 70% to 80% in the experimental group but was considered exploratory due to the limited number of trials and binary scoring method. A single session of combined 2D kinematic analysis and structured visual–verbal feedback was associated with immediate changes in selected planar serve mechanics and performance outcomes among university-level players. These findings should be interpreted as short-term performance adaptations rather than evidence of motor learning, long-term retention, or improvement in unmeasured biomechanical mechanisms.