1 Department of Physical Therapy for Musculoskeletal disorders & its surgeries, Faculty of Physical Therapy, Cairo University, Giza, Egypt
2 Department of Physical Therapy, Tebin Hospital, Cairo, Egypt
3 Department of Neurology and Clinical Neurophysiology, Kasralainy Cairo University, Giza, Egypt
Received: 20th Feb, 2026 | Revised: 4th Mar, 2026 | Accepted: 25th Mar, 2026 | Available Online: 10th Apr, 2026
Introduction: Myofascial chains are proposed to facilitate force transmission between anatomically connected muscles. However, functional electromyographic correlations within upper-limb kinetic chains remain insufficiently characterized.
Aim of study: To investigate whether myoelectrical connections exist between upper-limb muscles, those are anatomically linked by myofascial pathways.
Methods: A cross-sectional correlational study was conducted on 40 healthy adults (18–30 years). Surface electromyography (EMG) recorded activity of the upper trapezius, latissimus dorsi, and pectoralis major during maximal voluntary isometric contractions (MVIC) of extensor carpi radialis brevis (ECRB), extensor carpi ulnaris (ECU), and flexor carpi radialis (FCR). Spearman correlation coefficients were calculated.
Results: Only during FCR MVIC, a moderate positive correlation was observed between the upper trapezius and pectoralis major (r = 0.339, p = 0.03). All other correlations were weak and non-significant during ECRB and ECU contractions (p > 0.05).
Conclusion: Findings suggest limited and task-specific intermuscular coupling within proposed upper limb myofascial chains; overall anatomical continuity doesn't necessarily translate into strong functional EMG synchronizations.
Keywords: Kinetic chains; Myofascial connections; Electromyography; Upper limb; Muscle activation.
How to cite this article: Sayed MA, Abdelmegid SF, Abdelkader B, El-Khozamy HM. The Effect of Maximal Voluntary Isometric Contractions on Muscle Activity in Upper Limb Kinetic Chains. Int J Drug Deliv Technol. 2026;16(29s):69-74. DOI: 10.25258/ijddt.16.29s.9
Source of support: None.
Conflict of interest: The authors declare no conflict of interest.