Shoulder Coordination During Full-Can and Empty-Can Rehabilitation Exercises

Area of Science:

• Biomechanics
• Orthopedic Rehabilitation
• Sports Medicine

Background:

• Supraspinatus tears are common rotator cuff injuries.
• Exercise selection for rehabilitation remains debated.
• Shoulder coordination is crucial for arm function but often overlooked in exercise selection.

Purpose of the Study:

• To evaluate shoulder-motion coordination during common supraspinatus rehabilitation exercises.
• To determine the influence of load and motion direction on shoulder coordination.

Main Methods:

• A descriptive laboratory study involving 15 healthy men.
• Motion analysis using an optoelectronic system.
• Assessment of scapulohumeral rhythm and shoulder kinematics during full-can and empty-can exercises, with and without a 2.27-kg load.

Main Results:

• Multivariate interactions were observed between exercise type and humerothoracic elevation, and between load and humerothoracic elevation.
• The full-can exercise increased scapulohumeral rhythm (0.44 ± 0.22 ratio).
• Adding load increased glenohumeral elevation by 4° ± 1°.

Conclusions:

• The full-can exercise demonstrated normal shoulder coordination with increased glenohumeral contribution.
• The empty-can exercise showed increased scapulothoracic contribution, potentially limiting glenohumeral movement.
• Load can be safely incorporated into shoulder rehabilitation, as it maintains a natural scapulohumeral rhythm.