What is the best depth when leg pressing? Do you need to go “ass-to-grass” as deep as possible to maximize leg gains? A new study tackled this question, and the answer may surprise you.
LEG PRESS DEPTH STUDY
Here’s how the study went down: 23 participants, with an average of over seven years training experience, worked one leg with a partial range of motion (around 100 degrees of knee flexion) and worked the other leg with a full, individualized range of motion (141–165 degrees of knee flexion) over an eight-week period. This alternate leg design, as opposed to having some subjects do a partial ROM and others do a full ROM, allowed the exercise scientists to control for factors like genetics, nutrition, and recovery.
Before and after the study, quadriceps thickness was measured at multiple sites using ultrasound. Afterwards, growth was similar across all sites, with increases ranging from 2.2% to 7.3%. The scientists concluded that knee flexion ROM during leg pressing does not significantly influence quadriceps growth over a relatively short training period. So, no, you don’t need to go “ass-to-grass” (a.k.a. heels near glutes) on the leg press to maximize quad growth.
However, one of the study’s authors, Brad Schoenfeld, PhD, added this caveat: “It’s important to note that our focus here was on the quads. There is evidence that higher knee flexion angles during compound lower body exercise do influence muscle development in other muscles such as the glutes and adductors.” So, a deeper range of motion on the leg press may, in fact, be superior for overall lower body growth, though this study indicated it makes no significant difference in quad growth.
LEG PRESS DEPTH CONCLUSION
When leg pressing go to at least 100 degrees knee depth, which is slightly more than the quads-parallel to floor squat position. Going deeper will likely increase thigh adductor (groin) and glute growth but not quadriceps growth. Therefore, as with squat depth (deeper than parallel squats focus on the glutes and groin more), choose the depth you want dependent on your own goals and physique type. Want to focus mostly on your quads without a bigger butt? 100 degrees is sufficient. Want both glute and thigh growth? Go deeper.
