Differences in Lower‐Limb Kinematic–Electromyographic Coupling Patterns During Volleyball Spike Take‐Off Between Outside Hitters and Middle Blockers
Chen Chen, Jian Yu, Yang Wang, Cheng Chen, Youn-poong Oh, Shuangrui Liu, Zhenhao Lin, Yuwen ShangGuanBackground
This study compared lower‐limb kinematics and electromyographic characteristics between outside hitters (OH) and middle blockers (MB) during volleyball spike take‐off, aiming to delineate position‐specific joint‐angle profiles and relative muscle activation contributions.
Methods
Twelve national first‐class male volleyball athletes were recruited (OH, n = 6; MB, n = 6), and three‐dimensional kinematics (240 Hz) and surface electromyography (EMG; 2000 Hz) were synchronously collected. The analysis window was defined from right‐foot contact in the final approach step to bilateral toe‐off (T1–T4), with the braking phase set as T1–T3 and the propulsion phase as T3–T4; T3 was treated as the transition boundary between the two phases rather than as an independent phase. All participants were right‐handed hitters; therefore, the right side was defined as the dominant hitting side and the left side as the non‐dominant/non‐hitting side. Sagittal‐plane hip, knee, and ankle joint angles and phase‐specific relative iEMG contribution percentages of seven muscles were calculated and compared between groups.
Results
OH exhibited a smaller right/dominant hitting‐side hip angle than MB at T1, indicating a more flexed sagittal‐plane hip posture ( p < 0.01), and a smaller left/non‐dominant hitting‐side hip angle during T2–T3 ( p < 0.05). The right/dominant hitting‐side knee angle was consistently smaller in OH than in MB throughout T1–T3, indicating greater knee flexion ( p < 0.01). For the ankle joint, OH showed a greater left/non‐dominant hitting‐side sagittal‐plane ankle included angle during T1–T3 ( p < 0.01), whereas MB showed a greater right/dominant hitting‐side sagittal‐plane ankle included angle at T2 and T3 ( p < 0.01). During braking, OH showed a right/dominant hitting‐side iEMG contribution of 68.90% and a left/non‐dominant hitting‐side contribution of 31.09%, whereas MB showed 65.20% and 34.79%, respectively. During propulsion, OH primarily relied on the left/non‐dominant hitting side (59.40% vs. 40.60%), whereas MB demonstrated a more balanced bilateral activation pattern (49.63% vs. 50.37%).
Conclusion
OH and MB exhibited distinct lower‐limb kinematic–EMG coupling patterns during spike take‐off. OH showed greater sagittal‐plane hip and knee flexion in the early take‐off phase and a force‐production shift from right/dominant hitting‐side braking to left/non‐dominant hitting‐side propulsion, whereas MB demonstrated relatively larger joint angles and a more balanced bilateral activation pattern. These findings support position‐specific take‐off technique training and neuromuscular control strategies.