Squats make the outer part of your thigh near the knee grow more than leg extensions do.
Scientific Claim
Compound lower-body exercises performed through a full range of motion (e.g., squats) induce greater hypertrophy in the distal regions of mono-articular quadriceps muscles (e.g., vastus lateralis) compared to isolation exercises, likely due to training at longer muscle lengths.
Original Statement
“Much more surprising was that squats resulted in more growth in the quadriceps in the sweep, the vastus lateralis. This same pattern was observed in a previous study on leg presses, and the growth in both studies was somewhat concentrated near the knee, although the finding on that was not particularly strong, statistically speaking. The reason for this is biomechanically less clear that that for the rectus femoris, but it's possible that during squats, because the quads are trained at the longer muscle length, there is more growth in the vasti than the rectus femoris.”
Context Details
Domain
exercise
Population
human
Subject
back squats
Action
induce greater hypertrophy in
Target
the distal vastus lateralis compared to leg extensions
Intervention Details
Evidence from Studies
Supporting (3)
Comparison of Muscle Hypertrophy and Strength Adaptations Induced by Back Squat and Leg Extension Resistance Exercises.
Squats made the lower part of the big thigh muscle grow more than leg extensions did, which is exactly what the claim said would happen because squats stretch the muscle more.
This study found that doing squats all the way down (full range of motion) makes the thigh muscle work harder and get more oxygen-deprived, which helps muscles grow — supporting the idea that deep squats are better for building muscle than shallow ones.
Which ROMs Lead to Rome? A Systematic Review of the Effects of Range of Motion on Muscle Hypertrophy
Full squats (full range of motion) make the lower part of your thigh muscles grow more than partial squats, because stretching the muscle more during the exercise helps it grow better in that area.