How arm position changes shoulder muscle power
Shoulder abduction moment arms in three clinically important positions.
Not medical advice. For informational purposes only. Always consult a healthcare professional. Terms
Surprising Findings
Internal rotation during the Jobe test reduces the supraspinatus' abduction moment arm, contrary to its intended purpose of isolating this muscle.
The Jobe test is widely used to assess supraspinatus strength, yet this study shows the position actually decreases its mechanical advantage—suggesting it may not be optimal for testing this muscle.
Practical Takeaways
Consider testing supraspinatus strength with the arm at the side (neutral position) rather than in the Jobe position to maximize its mechanical advantage.
Not medical advice. For informational purposes only. Always consult a healthcare professional. Terms
Surprising Findings
Internal rotation during the Jobe test reduces the supraspinatus' abduction moment arm, contrary to its intended purpose of isolating this muscle.
The Jobe test is widely used to assess supraspinatus strength, yet this study shows the position actually decreases its mechanical advantage—suggesting it may not be optimal for testing this muscle.
Practical Takeaways
Consider testing supraspinatus strength with the arm at the side (neutral position) rather than in the Jobe position to maximize its mechanical advantage.
Publication
Journal
Journal of shoulder and elbow surgery
Year
2009
Authors
H. Ruckstuhl, J. Krzycki, N. Petrou, P. Favre, Tamara Horn, S. Schmid, E. Stussi
Related Content
Claims (3)
When your arm is resting down at your side, the supraspinatus muscle in your shoulder is in the best position to start lifting your arm out to the side—better than other nearby muscles—so doctors might use this position to test how well it’s working.
When you raise your arm to the side and twist it inward like in the Jobe test, it makes the main shoulder muscle less effective at lifting your arm because the leverage isn't as good.
Scientists can use your MRI scan and a computer to figure out how your shoulder muscles work in different positions — kind of like simulating how your shoulder moves from every angle.