Movement guide
Vastus intermedius
A deeper knee extensor beneath rectus femoris.
This deep muscle works with the other knee extensors.
01
Leg extension
Isolation · Machine
Also works
Rectus femoris, vastus lateralis, vastus medialis
How to perform
Align the machine axis with your knee. Extend your legs through a comfortable range and lower gradually.
Use controlled movement without kicking or bouncing.
Example volume · 2–3 sets × 10–15 reps
02
Front squat
Compound · Barbell
Also works
Other quadriceps, gluteus maximus, adductors; trunk stabilizers
How to perform
Hold the bar in a secure front rack. Sit down between your hips while keeping the torso braced. Drive through the feet to stand.
Keep your elbows lifted and knees tracking with your toes.
Example volume · 3–4 sets × 4–8 reps
References
openstax.orgCommunity draft · awaiting expert review