Shoulder angle effects on neuromuscular activation and rapid force production: sEMG time-frequency and force-time analyses
FRONTIERS IN BIOENGINEERING AND BIOTECHNOLOGY, cilt.14, 2026 (SCI-Expanded, Scopus)
- Yayın Türü: Makale / Tam Makale
- Cilt numarası: 14
- Basım Tarihi: 2026
- Doi Numarası: 10.3389/fbioe.2026.1821665
- Dergi Adı: FRONTIERS IN BIOENGINEERING AND BIOTECHNOLOGY
- Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus, BIOSIS, Compendex, INSPEC, Directory of Open Access Journals, Natural Science Collection (ProQuest), Biological Science Database (ProQuest), Health Research Premium Collection (ProQuest)
- Açık Arşiv Koleksiyonu: AVESİS Açık Erişim Koleksiyonu
- İstanbul Üniversitesi Adresli: Hayır
Özet
Introduction Maximal isometric shoulder force production constitutes an angle-dependent neuromuscular task; changes in shoulder elevation can meaningfully modify the relative contribution of glenohumeral and scapulothoracic musculature through concomitant alterations in moment arms, length-tension operating ranges, and the direction of the resultant force vector. Although shoulder testing across different arm elevations is widely used to infer functional capacity and rehabilitation readiness, the underlying neuromuscular strategies are still most often described using amplitude-based surface electromyography (sEMG) metrics or peak mechanical outcomes alone. However, it remains unclear how shoulder elevation angle influences time-frequency features of muscle activation and force-time characteristics.Methods Twenty-four elite male athletes performed maximal isometric efforts. sEMG signals were analyzed wavelet-based mean frequency. Rate of force development (RFD) and mechanical impulse values were calculated from the raw force-time data across predefined intervals from contraction onset to 50, 100, 150, 200, 250 ms, and peak force.Results Mean frequency was higher for the anterior deltoid and pectoralis major at 90 degrees than at 135 degrees and 180 degrees. For the serratus anterior and infraspinatus, mean frequency was greater at 135 degrees and 90 degrees than at 180 degrees. In contrast, upper and lower trapezius showed higher mean frequency at 180 degrees than at 135 degrees and 90 degrees. No significant position-dependent differences were observed for the middle and posterior deltoid. Mechanically, the 180 degrees condition showed higher force, RFD, and impulse values compared to the other angles.Discussion Angle-dependent task sharing was observed within the shoulder complex, whereby lower elevation angles are associated with greater involvement of anterior musculature, while the overhead position is characterized by increased involvement of scapular stabilizers and higher rapid force-production outputs. These angle-specific neuromechanical patterns may contribute to more detailed shoulder profiling in elite athletes.