Estimation of the Relationship between External Biceps Brachii Deformation and Isometric Contraction Level Using Motion Capture Technique

The aim of this study was to investigate the potential of Motion Capture (MoCap) technique in the extraction of information about Biceps Brachii (BB) surface deformation for the characterization of its activation under isometric conditions. Thus, the dominant BB muscles of five healthy male subjects were tested using high density optic sensors (41 markers) and 18 infrared cameras. For each subject, ultrasound images were taken in order to extract architectural parameters (muscle length, boundaries and position). Afterwards, the 4 mm markers were placed in a lozenge shape by respecting the obtained boundaries. Four contraction levels: 20, 40, 60 and 80% of the Maximum Voluntary Contraction (MVC) were recorded in parallel with the corresponding 3D position of the markers. Fitting procedure in both 2D and 3D was proceeded to extract deformation information. Analysis of the obtained results showed that the curvature of the BB is directly correlated to the level of contraction. Furthermore, parameters obtained from ellipsoid fitting of the 3D dataset, showed monotonic relationship with the muscle contraction level.