The Study
Hypertrophic Effects of Single- versus Multi-Joint Exercise: A Direct Comparison Between Knee Extension and Leg Press.
This study saw that when people did two different leg exercises, their muscles got a little bigger — but we don’t know if the exercises actually caused the growth or if something else did. So we can only say the exercises were linked to bigger muscles, not that they made them bigger.
Analysis score
Maximum 90 for a randomized controlled trial.
Where the score came from
Two different leg exercises were tested: one where you push with just your knees (knee extension) and one where you push with your whole leg (leg press).
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 531 / 100
Quality score
Participants are randomly assigned to treatment or control groups, minimizing bias. The gold standard for testing whether an intervention causes an effect.
Key takeaways
Summary
Based on the study abstract and findings.
- 1Yes — if you want bigger glutes and inner thighs, leg press is better.
- 2If you want bigger front thigh muscles, knee extension is better.
- 3Knee extension made the front thigh muscle (rectus femoris) grow 13.2%.
- 4Leg press made your butt (gluteus maximus) grow 15.4% and inner thigh (adductor magnus) grow 6.2%.
- 5Both made the rest of the thigh muscles grow about the same.
Score breakdown, methodology, conflicts of interest, evidence analysis & raw study data
Publication
Journal
Medicine and science in sports and exercise
Year
2026
Authors
Momoka Kinoshita, S. Maeo, Yuuto Kobayashi, Yuuri Eihara, Naoya Nishizawa, Yuki Kusagawa, Takashi Sugiyama, T. Wakahara, Hiroaki Kanehisa, Tadao Isaka
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Claims (10)
The rectus femoris muscle exhibits greater hypertrophic adaptation to isolated knee extension exercises than to compound movements involving hip and knee flexion due to biomechanical limitations in force production during multi-joint movements.
Isolation exercises targeting a single joint (e.g., leg extensions) produce greater hypertrophy in bi-articular muscles (e.g., rectus femoris) compared to multi-joint compound movements (e.g., squats) due to avoidance of active insufficiency.
Doing leg extensions might grow your front thigh muscle more than leg presses, even though both workouts work the other big thigh muscles just as hard.
Indirect sets (where a muscle acts as a secondary force generator) stimulate muscular hypertrophy but contribute less to growth than direct sets (where the muscle is the primary force generator).
Leg presses make your butt and inner thigh muscles bigger, but leg extensions don’t affect those muscles at all.
Doing leg presses and leg extensions for 12 weeks both make your main thigh muscles bigger about the same amount, but leg presses also make your butt and inner thigh muscles grow more, while leg extensions make the front part of your thigh (rectus femoris) grow much more.
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.