This project was conducted by Hugo Hakem as part of BIOEC209 Advanced Orthopedic Mechanic Supervised by Prof. Tony M. Kheaveny departement of Mechanical Engineering and Bioengineering, at University of California Berkeley.
Matlab model to study the effect of the barbell positioning on the shoulders and of the hand spacing on this barbell on the orientation of the shoulder joint reaction force in athlete performing back-squat.
This study has been intended to provide guidance for athlete who want to reduce their shoulder discomfort while doing back squat.
Two parameters have been studied, the barbell positioning on the shoulder ∆H, varying from the upper to the lower portion of the rear deltoid and the hand spacing on the barbell ∆H_and, measured from the edge of the shoulder.
A biomechanical static analysis has been performed and solved on MATLAB. The shoulder discomfort has been measured as being directly correlated with the orientation of the shoulder joint reaction force in the frontal and sagittal plane. Optimal values for ∆H and ∆H_and have thus been determined by minimizing the shoulder discomfort.
Finally, the impact of morphology on these optimal positions have been studied. Overall, a small ∆H, or a high barbell positioning is preferred but individual with longer humerus or forearm would feel more comfortable with a low barbell positioning. The hand spacing ∆H_and must stay between 70% to 80% of the arm length, but a grip closer from the higher end may be preferred for individual with longer forearm. In any case, having hands too close from the body and a low barbell positioning must be avoid.
For a better comprehension of how the Studies have been conducted, please download the pdf Report.
To run the code by yourself and have a more extensive analysis, please download the Matlab folder.
- Run the the matlab code: Shoulder_force.m
- To plot forces, angle of these forces in the shoulder joint, according the Barbell positioning and Hand Spacing.
- Run the the matlab code: Shoulder_force_with_variable_body.m
- To study the effect of bodies length on the angle of shoulder joint reaction force (associated to Shoulder discomfort, see Report).