If you're new to working out, doing leg presses twice a week for 12 weeks can noticeably grow your butt and inner thigh muscles, but doing just knee extensions won’t help those muscles much.

53

Pro

0

Against

Evidence from Studies

Supporting (1)

53

Community contributions welcome

53

Hypertrophic Effects of Single- versus Multi-Joint Exercise: A Direct Comparison Between Knee Extension and Leg Press.

Cross-Sectional Study

Human

2026 Feb 5

The study found that leg presses made the glutes and inner thigh muscles bigger, but knee extensions didn’t — just like the claim says.

Contradicting (0)

0

Community contributions welcome

No contradicting evidence found

Gold Standard Evidence Needed

According to GRADE and EBM methodology, here is what ideal scientific evidence would look like to definitively prove or disprove this specific claim, ordered from strongest to weakest evidence.

Source Study

Hypertrophic Effects of Single- versus Multi-Joint Exercise: A Direct Comparison Between Knee Extension and Leg Press.

Score: 53

DOI: 10.1249/mss.0000000000003957

Similar Assertions

Leg presses make your butt and inner thigh muscles bigger, but leg extensions don’t — if you want to grow those muscles, leg presses are the better choice.

31

0

89%

If you're new to working out, doing leg presses twice a week might build more leg muscle in less time than just doing knee extensions, because leg presses work more muscles at once — like your quads, butt, and inner thighs.

53

0

86%

If you're new to working out, doing leg presses or knee extensions twice a week for 12 weeks will grow your thigh muscles about the same amount—so pick the one you like!

53

0

82%

Leg presses make your butt and inner thigh muscles bigger, but leg extensions don’t affect those muscles at all.

31

0

81%

Leg presses make your butt and inner thigh muscles bigger, but leg extensions don’t affect those muscles at all.

31

0

81%