Ting Wang

Fatigue causes the lower limb to land in an injury-prone state, but the underlying neuromuscular control changes remain unclear. This study aims to investigate lower limb muscle synergies during landing in basketball players, both before and after fatigue, to examine alterations in neuromuscular control strategies induced by fatigue. Eighteen male recreational basketball players performed landing tasks pre- and post-fatigue induced by 10 × 10 countermovement jumps. Electromyographic (EMG) data from eight muscles, including the erector spinae (ES), rectus abdominus (RA), gluteus maximus (GM), rectus femoris (RF), biceps femoris (BF), lateral gastrocnemius (LG), soleus (SM), and tibialis anterior (TA) muscles, were analyzed using non-negative matrix factorization to extract muscle synergies. Post-fatigue results revealed significant changes: synergy primitive 1 decreased before landing (18–30% phase) and synergy primitive 2 decreased after landing (60–100% phase). Muscle weights of the LG and SM in synergy module 2 increased. Fatigue reduced synergistic muscle activation levels, compromising joint stability and increasing knee joint loading due to greater reliance on calf muscles. These changes heighten the risk of lower limb injuries. To mitigate fatigue-induced injury risks, athletes should improve thigh muscle endurance and enhance neuromuscular control, fostering better synergy between thigh and calf muscles during fatigued conditions.

Objectives: The present study evaluated if lower limb muscle pre- and co-activation was associated with the biomechanics of knee joint control during backward step single-leg landings following a badminton overhead stroke. Methods: Three-dimensional biomechanics data of the knee joint and electromyographic data of lower limb muscles were collected from 34 badminton players. Linear regression analysis of gluteus maximus, quadriceps, hamstrings, gastrocnemius pre-and muscle co-activation in relation to peak knee flexion angle, knee valgus angle and moment, peak extension moment, and tibial anterior shear force in participants 100 ms before initial touchdown were analyzed. Results: Increased quadriceps pre-activation predicts increased knee valgus angle (R2 = 0.48, P < 0.001). Greater Lateral Hamstring/Quadriceps co-contraction predicts increased peak knee extension moment (R2 = 0.39, P < 0.001). Greater lateral gastrocnemius/quadriceps co-contraction predicts an increased peak knee valgus moment (R2 = 0.20, P = 0.0073). No EMG pre-activity parameters were predictors (P > 0.05) for knee flexion angle and anterior tibial shear force. Conclusion: These findings suggested that pre-activation of the quadriceps or co-contraction ratio of the lateral hamstrings to the quadriceps or lateral gastrocnemius to the quadriceps would be positively associated with the risk of non-contact anterior cruciate ligament (ACL) injuries during a single-leg landing following a badminton backward step overhead stroke.

Basketball victory relies on an athlete’s skill to make precise shots at different distances. While extensive research has explored the kinematics and dynamics of different shooting distances, the specific neuromuscular control strategies involved remain elusive. This study aimed to compare the differences in muscle synergies during basketball shooting at different distances, offering insights into neuromuscular control strategies and guiding athletes’ training. Ten skilled shooting right-handed male basketball players participated as subjects in this experiment. Electromyographic (EMG) data for full-phase shooting were acquired at short (3.2 m), middle (5.0 m), and long (6.8 m) distances. Non-negative matrix decomposition extracted muscle synergies (motor modules and motor primitives) during shooting. The results of this study show that all three distance shooting can be broken down into three synergies and that there were differences in the synergies between short and long distances, with differences in motor primitive 1 and motor primitive 2 at the phase of 45% - 59% (p < 0.001, t* = 4.418), and 78% - 88% (p < 0.01, t* = 4.579), respectively, and differences in the motor module 3 found in the differences in muscle weights for rectus femoris (RF) (p = 0.001, d = -2.094), and gastrocnemius lateral (GL) (p = 0.001, d = -2.083). Shooting distance doesn't affect the number of muscle synergies in basketball shooting but alters synergy patterns. During long distance shooting training, basketball players should place more emphasis on the timing and synergistic activation of upper and lower limbs, as well as core muscles.