Enhancing Shoulder Kinetic Chain Rehabilitation Using Elastic Resistance in Kneeling Positions. A Kinematics Study

OBJECTIVE: To evaluate the 3D kinematics of the scapula and trunk during a kneeling anterior/posterior movement in asymptomatic adults, (a) without resistance and (b) with two complementary resistance arrangements integrating the kinetic chain. DESIGN: A controlled laboratory study using within-group comparisons. METHODS: Thirty-six healthy young adults of both sexes, and without shoulder or lower quadrant problems, participated in this study. Three-dimensional scapular kinematics were recorded with an electromagnetic tracking device during shoulder elevation for both the unloading (active) and loading (resisted) conditions. Data for scapular and trunk kinematics were analyzed at 15°, 30°, 60°, 90°, and 120° of humerothoracic elevation and lowering. A repeated measures ANOVA was conducted to investigate different interactions between resistance, phase, and humerothoracic elevation for scapular and trunk kinematics. RESULTS: There was an effect of resistance on internal/external rotation and anterior/posterior tilt, and an effect of phase on anterior/posterior tilt. Trunk motion and resistance influenced axial rotation and lateral flexion, while phase impacted lateral flexion and extension. The scapula exhibited an interaction between phase-by-humerothoracic elevation at 60° of internal rotation during the lowering phase and between resistance-by-humerothoracic elevation at 15° and 60° for upward rotation. Increased resistance induced an anterior tilt of the scapula during the arm raising phase. The trunk exhibited an interaction between phase-by-humerothoracic elevation range 15-30° of lowering phase. There were no significant differences in scapulohumeral rhythm. CONCLUSION: Increased resistance impacted scapular and trunk kinematics, significantly enhancing stability but not altering scapulohumeral rhythm.