How arm position changes muscle tiredness
Effect of shoulder angle on the activation pattern of the elbow extensors during a submaximal isometric fatiguing contraction
Not medical advice. For informational purposes only. Always consult a healthcare professional. Terms
Surprising Findings
Only the long head of the triceps showed increased activation at 90° shoulder flexion, despite all heads contributing to elbow extension.
Most people assume all parts of a muscle work together equally; this shows selective activation based on biomechanics, especially during fatigue.
Practical Takeaways
Be mindful of shoulder position during endurance-focused triceps exercises—keeping the shoulder at 0° may improve performance and reduce fatigue.
Not medical advice. For informational purposes only. Always consult a healthcare professional. Terms
Surprising Findings
Only the long head of the triceps showed increased activation at 90° shoulder flexion, despite all heads contributing to elbow extension.
Most people assume all parts of a muscle work together equally; this shows selective activation based on biomechanics, especially during fatigue.
Practical Takeaways
Be mindful of shoulder position during endurance-focused triceps exercises—keeping the shoulder at 0° may improve performance and reduce fatigue.
Publication
Journal
Muscle & Nerve
Year
2010
Authors
Andrew W. Davidson, C. Rice
Related Content
Claims (5)
If a young guy is holding his arm out straight while his shoulder is raised to shoulder height, he’ll get tired faster than if his shoulder is down at his side — even if he’s using the same amount of effort with his elbow.
When you hold a muscle squeeze until it gets tired, different parts of the triceps respond differently — especially depending on how your shoulder is positioned. One part (the long head) changes activity based on shoulder angle, but the others don’t.
When young guys do a tiring arm exercise, bending the shoulder to 90 degrees makes one part of the triceps work harder near the end compared to when the shoulder is straight, suggesting shoulder position changes how that muscle is used when tired.
When young guys do a tiring arm exercise, they're weaker afterward if their shoulder is bent at 90 degrees compared to when it's straight — their arm strength drops more in the bent position.
The long part of the triceps doesn't work much when you push weights overhead because of how it's connected across two joints and how your shoulder moves.