Browse evidence-based analysis of health-related claims and assertions
Doing exercises where you push the weight up (concentric) makes more muscle repair cells grow than doing exercises where you lower the weight slowly (eccentric), at least in young men training for 12 weeks.
Correlational
Which leg exercise you choose matters: leg extensions grow the front thigh muscle more, squats grow the lower outer thigh more and make you stronger at squats—but both help you get stronger at leg extensions.
Causal
Even if you only do squats, you still get almost as strong at leg extensions as someone who only does leg extensions—so squats aren’t useless for that movement.
If you want to get stronger at squats, doing squats is way better than doing leg extensions—but if you want to get stronger at leg extensions, both exercises work about the same.
Squats make the lower part of the outer thigh muscle grow more than leg extensions do, probably because squats involve more hip and knee movement together.
Doing leg extensions makes the front thigh muscle grow more evenly along its length than doing squats, which don’t stimulate that muscle as much.
The side muscle of your thigh doesn’t grow any more with drop sets than with regular sets—no matter where you measure it.
Drop sets don’t make you do more reps or sets, but they let you lift heavier weights for more total work—which is probably why your muscle grows more in some spots.
Quantitative
After 15 weeks of leg workouts, the men’s quadriceps muscles grew by about 13%, measured precisely with MRI scans.
Descriptive
When scientists looked at how each person changed over time (not just comparing different people), they found a much stronger link between muscle growth and strength than previous studies using different methods.
When scientists looked at what made these men stronger, muscle growth explained over five times more of the improvement than changes in how their nerves activated their muscles.
When these men got stronger, their muscle signals (measured by EMG) also got stronger—but not as strongly as their muscles grew.
When young men who had never lifted weights before trained their legs for 15 weeks, the more their leg muscles grew, the stronger they got—this link was extremely strong.
Single-leg lunges helped both legs get better at turning quickly, but double-leg squats only helped the stronger leg.
Both training methods made athletes jump higher and turn faster, but didn’t make them run straight-line sprints any faster.
Single-leg lunges helped athletes slow down better with their weaker leg after turning, more than double-leg squats did.
Both types of training made athletes stronger and more powerful, but squats with both legs made them significantly more powerful in the squat than lunges did.
Doing squats with both legs on a special machine for six weeks made the outer thigh and outer calf muscles grow more than doing single-leg lunges.
Doing single-leg lunges with a special machine for six weeks made the inner thigh and inner knee muscles grow more than doing regular squats with both legs.
How much your butt muscles 'fire up' during your first hip thrust or squat doesn’t tell you how much they’ll grow over time — the feeling during the workout isn’t a reliable guide to results.
Doing squats or hip thrusts helps you get stronger at deadlifts and pushing against a wall about the same amount — neither exercise gives you a big edge over the other for these other movements.
If you want to get stronger at squats, you need to squat; if you want to get stronger at hip thrusts, you need to do hip thrusts. Training one doesn’t make you much stronger at the other.
Squats build your thigh muscles (quads and inner thighs) more than hip thrusts do, because squats involve more knee and hip movement that engages those muscles more.
Doing hip thrusts or squats for 9 weeks with the same total work builds your butt muscles just as much, even though hip thrusts feel like they work your butt harder during the exercise.