Liftworthy
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Liftworthy

Every exercise ranked by research, by lifters and by results. Find what’s S-tier for your goal, then train it.

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Explore/Quads

Leg Extension

MachineIsolationEasy to learn
Front
Back
Primary

Works

Quads

You need

Leg extension

How to do itPictures · 3 steps
Ankle pad
1Start
Ankle pad
2Top
Main muscles
  1. 1Knee lined up with the machine pivot
  2. 2Lean back slightly to stretch the rectus femoris
  3. 3Lower slowly into the bend

Most common mistake

Kicking the weight up and dropping it.

Watch a demo

Good for

  • Top 10 for quads
  • Keeps the work on the target muscle
  • Easy to keep adding weight

Compare with

vs Reverse Nordicvs Sissy Squatvs Belt Squat
A
For quads
#4 of 33
See the full list →
Research
83
Scored by hand
Results
Soon
From the app
How lifters rate itBe the first
S
A
B
C
D
F
Why research scores it 832 studies
Target tensionExcellent
Loaded stretchGood
ProgressionExcellent
Low costStrong

The only exercise that fully loads the rectus femoris: it grew all three of its regions in one trial, where Smith squats didn’t. Lean back to stretch it more.

  • Pedrosa et al., 2022 · Trial: Leg extensions trained in the stretched half of the range produced more quad growth than the shortened half. (45 untrained women.)
  • Zabaleta-Korta et al., 2021 · Trial: Leg extensions grew all three regions of the rectus femoris; Smith machine squats grew only the middle of the vastus lateralis. (Small study; volume and intensity were matched.)

Research behind these criteria

  • Target tension: Zabaleta-Korta et al., 2021 · Kinoshita et al., 2023
  • Loaded stretch: Maeo et al., 2021 · Maeo et al., 2023 · Pedrosa et al., 2022 · Kassiano et al., 2023
  • Progression: Plotkin et al., 2022 · Pelland et al., 2026
  • Low cost: Schoenfeld et al., 2021 · Refalo et al., 2023
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