Decoding free-throw accuracy: a 2D biomechanical comparison of shooting mechanics in athletes and novice basketball players

This study examined the key biomechanical determinants of free-throw accuracy by comparing 2D kinematic characteristics between trained basketball athletes and novice players. Fifty right-hand dominant participants (25 athletes, 25 novices; age 18–24 years) performed 20 standardized free-throw trials after familiarization. Upper and lower-limb joint angles, trunk lean, hand velocity, and ball-release parameters (height, angle, velocity) were extracted from sagittal-plane videos using Dartfish software, with high intra- and inter-rater reliability (ICC = 0.88–0.95). Successful and unsuccessful shots were analyzed separately. Statistical comparisons used independent t -tests or Mann–Whitney U -tests with Bonferroni correction, and effect sizes (Cohen's d) were calculated. Correlations between kinematic variables and shot success were examined for each group. Athletes had superior anthropometrics, physical performance, and higher absolute kinematic values than novices. Successful shots in both groups featured greater elbow extension (Athletes: 158.1 ± 3.1° vs. 152.3 ± 3.8°; Novices: 150.5 ± 4.0° vs. 145.0 ± 4.4°) and higher ball release height (Athletes: 2.28 ± 0.06 m vs. 2.19 ± 0.07 m; Novices: 2.15 ± 0.08 m vs. 2.05 ± 0.09 m), which showed the strongest correlations with success (r ≥ 0.63, p < 0.01). Shoulder, wrist flexion and hand velocity contributed moderately, whereas lower-limb and trunk kinematics mainly supported stability and energy transfer. Directional patterns for successful shots were consistent across skill levels, though athletes exhibited higher absolute values and reduced variability. Free-throw accuracy is primarily determined by distal segment mechanics, particularly elbow extension and release height, supported by coordinated shoulder elbow wrist sequencing. These findings provide evidence-based guidance for coaching interventions emphasizing release mechanics over lower-limb force production to enhance shooting performance across skill levels.