A study on the correlation between knee muscle strength and agility in competitive Wushu Changquan athletes

Background: Changquan (Long Fist) is a competitive martial arts discipline characterized by complex offensive and defensive techniques requiring high levels of coordination, agility, and strength. The knee joint, as the central link between the upper and lower limbs, plays a vital role in generating power and maintaining movement stability. This study investigated the relationship between knee joint muscle strength and agility among competitive Changquan athletes. Method: A mixed-method design involving literature review, expert interviews, questionnaire survey, and experimental testing was employed. Twelve male Changquan athletes underwent bilateral isokinetic knee strength assessments at angular velocities of 60°/s (maximal strength) and 240°/s (explosive strength) using a Biodex System 4 Pro dynamometer. Peak torque (PT), relative peak torque (PT/BW, %BW), flexor-extensor ratio (F:E), total work (TW), and endurance ratio (ER) were recorded. Agility was evaluated using the T-test and 15 s push-up test. Pearson correlation analysis examined relationships between strength and agility parameters. Results: Results showed that knee extensor strength exceeded flexor strength, with mean peak torque values of 236.39 ± 17.62 N·m and 131.99 ± 13.54 N·m at 60°/s, and 133.85 ± 12.47 N·m and 97.85 ± 10.61 N·m at 240°/s. The right side was slightly stronger, though differences were not significant (p > 0.05). Athletes achieved excellent agility scores (T-test: 9.31 ± 0.16 s; push-ups: 9.66 ± 0.89 reps). Strong positive correlations were found between agility and slow flexor peak torque (r = 0.699, p = 0.011), slow extensor relative peak torque (r = 0.578, p = 0.049), and total work of slow flexors (r = 0.619, p = 0.032). The degree of correlation with agility followed the order: maximal strength > explosive power > strength endurance. Conclusion: Competitive Wushu Changquan athletes possess relatively balanced bilateral knee muscle strength; however, the flexor muscles are comparatively weaker, which may increase the risk of sports injury. Knee joint muscle strength particularly maximal and explosive flexor capacity is a key determinant of agility in competitive Wushu Changquan athletes. Balanced enhancement of flexor and extensor strength is recommended to improve performance efficiency, technical execution, and injury prevention. These findings provide a scientific basis for optimizing strength and conditioning programs for Changquan athletes through targeted flexor-extensor development to improve agility, performance precision, and injury prevention.