Khaled Abuwarda, Abdulazeem Alotaibi, Abdel-Rahman Akl
Overall, the findings indicate that muscle co-activation is segment-specific and adapted to the mechanical demands of each joint within the kinetic chain. Imbalances such as excessive wrist co-activation or insufficient proximal stabilization may increase injury risk. Therefore, injury prevention in para-badminton should focus on optimizing wrist stability, maintaining elbow muscle balance, enhancing shoulder control, and improving trunk stability to support efficient force transfer and performance.
OBJECTIVE: This study aimed to examine and compare muscle activation and co-activation across the backswing and forward swing phases of the para-badminton smash to improve understanding of phase-specific neuromuscular coordination that may inform future biomechanical and injury-related research.
METHODS: Nine elite para-badminton players were recruited for the study (body mass: 79.0 ± 7.9 kg; height: 172.1 ± 5.2 cm). Surface electromyography (sEMG) signals were recorded using a wireless EMG system, and data were collected from eight muscles (flexor carpi ulnaris, extensor carpi ulnaris, biceps brachii, triceps brachii, infraspinatus, latissimus dorsi, rectus abdominis, and erector spinae longissimus).
RESULTS: The results indicated that the wrist (flexor carpi ulnaris and extensor carpi ulnaris) and elbow (biceps and triceps) muscles showed significantly greater activation during the forward swing (p < 0.01-0.001), with peak activity in the early-to-mid acceleration phase; however, only the wrist demonstrated a significant change in the co-activation index (CoI) (p < 0.001), while elbow agonist-antagonist balance remained stable. At the shoulder, the infraspinatus maintained consistent activation, whereas the latissimus dorsi was selectively recruited during the forward swing (p < 0.01), resulting in an increased CoI (p < 0.001). Similarly, trunk muscles exhibited phase-specific behavior, with stable erector spinae activity and significant rectus abdominis recruitment during the forward swing (p < 0.001), leading to elevated trunk CoI. Overall, these findings indicate coordinated, segment-specific modulation of activation and co-activation to support force generation and stabilization during the acceleration phase.
CONCLUSION: Overall, the findings indicate that muscle co-activation is segment-specific and adapted to the mechanical demands of each joint within the kinetic chain. Imbalances such as excessive wrist co-activation or insufficient proximal stabilization may increase injury risk. Therefore, injury prevention in para-badminton should focus on optimizing wrist stability, maintaining elbow muscle balance, enhancing shoulder control, and improving trunk stability to support efficient force transfer and performance.