Source credit: PubMed – Medicine and Science in Sports and Exercise. Full text is available via PubMed Central.
Short summary
A PubMed-indexed July 2026 study in Medicine and Science in Sports and Exercise directly compared two common quad-training choices: single-joint knee extensions and multi-joint leg press. Seventeen untrained adults trained one leg with knee extensions and the other with leg press for 12 weeks, using MRI to track changes across individual lower-body muscles. Both approaches grew most of the quadriceps, but knee extensions produced much larger rectus femoris gains, while leg press also grew the gluteus maximus and adductor magnus.
Why it matters for lifters
For lifters trying to build legs efficiently, the study supports the leg press as a high-value compound machine for overall quad, glute, and adductor development. It also argues against treating compound work as a complete replacement for isolation work. If the goal is to bring up the rectus femoris specifically, knee extensions still appear useful because that muscle did not respond the same way to leg press in this trial.
What to watch next
This was a small study in untrained adults, so the next questions are whether the same pattern holds in trained bodybuilders, older lifters, women and men analyzed separately, and programs that combine squats, presses, and extensions. Watch for longer trials that compare real bodybuilding routines instead of single-exercise protocols.
Disclaimer: This article is for informational purposes only and is not medical advice. People with knee, hip, back, or tendon issues should work with a qualified health professional or coach before changing lower-body training volume, loading, or exercise selection.