How sitting position changes leg muscle use during leg lifts
Hip flexion angle affects longitudinal muscle activity of the rectus femoris in leg extension exercise
Not medical advice. For informational purposes only. Always consult a healthcare professional. Terms
Surprising Findings
Subjective effort did not match objective muscle activation patterns.
Most trainers and lifters rely on the 'mind-muscle connection' or how hard a muscle feels like it's working. This study shows that feeling isn’t reliable—especially in trained individuals.
Practical Takeaways
Set your leg extension machine seat so your hips are bent at about 40 degrees to better activate the upper part of your quads.
Not medical advice. For informational purposes only. Always consult a healthcare professional. Terms
Surprising Findings
Subjective effort did not match objective muscle activation patterns.
Most trainers and lifters rely on the 'mind-muscle connection' or how hard a muscle feels like it's working. This study shows that feeling isn’t reliable—especially in trained individuals.
Practical Takeaways
Set your leg extension machine seat so your hips are bent at about 40 degrees to better activate the upper part of your quads.
Publication
Journal
European Journal of Applied Physiology
Year
2023
Authors
H. Mitsuya, K. Nakazato, T. Hakkaku, T. Okada
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Claims (6)
When male bodybuilders do leg extensions with their hips bent at 80 degrees, the lower part of their front thigh muscle works harder than the middle part, according to MRI scans.
When male bodybuilders do leg extensions with their hips bent at 40 degrees, the front thigh muscle works harder in certain areas than when their hips are bent more at 80 degrees.
When male bodybuilders do leg extensions with their hips more bent, the top and middle parts of their front thigh muscle don’t work as hard — they show less activity and fatigue compared to when the hips are straighter.
Just because your quad feels like it's working hard during leg lifts doesn't mean that part of the muscle is actually lighting up — especially in people who train regularly.
For male bodybuilders doing leg extensions, bending the hips to 40 degrees might work the top part of the front thigh muscle better than bending to 80 degrees, based on brain scan-like results showing more muscle activity at the smaller angle.