The Study
Hip flexion angle affects longitudinal muscle activity of the rectus femoris in leg extension exercise
This study shows what happened to leg muscles in 9 bodybuilders when they did leg extensions at different hip angles. It can tell us that muscle activity looked different depending on the angle, but it can't prove that changing the angle caused the difference or that it will help build muscle over time.
Analysis score
Maximum 44 for a cross-sectional study.
Where the score came from
This study checks which part of the front leg muscle works hardest during leg extensions depending on how much you bend your hips.
Where does this study sit?
Reviews of RCTs (Meta-analyses)
Max 100Randomized Trials
Max 90Reviews of Cohort Studies
Max 85Cohort Studies
Max 72Reviews of Case-Control Studies
Max 63Case-Control Studies
Max 58Cross-Sectional & Case Series
Max 50Expert Opinion
Max 544 / 100
Quality score
Snapshots of a population at a single point in time, or descriptions of small groups. Can identify correlations and prevalence, but cannot determine cause and effect.
Key takeaways
Summary
Based on the study abstract and findings.
- 1Yes, this matters because choosing the right seat position in the gym can help target specific parts of the leg muscle for better growth.
- 2At 40° hip bend, the top part of the muscle worked harder.
- 3At 80°, the lower part worked more.
- 4Feeling the burn didn’t always mean the muscle was actually working more.
Score breakdown, methodology, conflicts of interest, evidence analysis & raw study data
Publication
Journal
European Journal of Applied Physiology
Year
2023
Authors
H. Mitsuya, K. Nakazato, T. Hakkaku, T. Okada
Related Content
Claims (9)
When performing leg extensions with the hip fully extended, the rectus femoris muscle grows larger than the vastus lateralis muscle because the rectus femoris spans two joints and is stretched more during this movement.
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.
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.
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.