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Vastus Intermedius股中间肌

Legs · Intermediate (L2) · Anterior · 5 exercises

Function

A knee extensor hidden directly beneath the rectus femoris, with deep-running fibers. As it grows it thickens the whole quadriceps from the inside out.

Best Exercises & Form Cues

• Barbell Back Squat

  Equipment

  Barbell + squat rack

  Sets & Reps

  3-5 sets × 5-8 reps · rest 2-3 min

  How to do it

  Feet shoulder-width, toes slightly out; sit down between your heels, knees tracking over toes, to thigh-parallel or below, braced throughout.

  Common mistakes

  Knees caving in, heels lifting, lower back collapsing into a forward lean on the way up

• Leg Press

  Equipment

  45° leg press machine

  Sets & Reps

  3-4 sets × 10-15 reps · rest 2 min

  How to do it

  Feet shoulder-width on the platform; lower to about 90° of knee flexion without the hips curling off the pad; press up without locking the knees; back stays flat on the pad.

  Common mistakes

  Descending too deep (hips roll up, lumbar risk), locking the knees, knees caving in

• Leg Extension (Standard)

  Equipment

  Leg extension machine

  Sets & Reps

  3-4 sets × 12-15 reps · rest 60-90 s

  How to do it

  Knee aligned with the pivot; the whole quadriceps (including the deep vastus intermedius) kicks to full extension with a top squeeze; 3-second negative; glutes stay on the seat.

  Common mistakes

  Swinging the legs, partial reps, hips lifting

• Hack Squat

  Equipment

  Hack squat machine

  Sets & Reps

  3-4 sets × 8-12 reps · rest 2 min

  How to do it

  Back flat on the pad, shoulders under the pads; feet mid-low and slightly wider than shoulder-width; descend vertically to thigh-parallel; drive up evenly through the quads; no knee lockout at the top.

  Common mistakes

  Hips lifting off the back pad, knees caving, partial reps

• Front Squat

  Equipment

  Barbell + rack (front rack)

  Sets & Reps

  3-4 sets × 5-8 reps · rest 2-3 min

  How to do it

  Bar racked on the clavicles and front delts; elbow tips high to secure the bar; squat more upright than a back squat to thigh-parallel; brace and drive as one unit.

  Common mistakes

  Elbows dropping (bar slides forward), heels lifting, excessive forward lean

Stretching & Recovery

• Lunge hip-drop with ankle pull
• Deep squat bottom hold

Other muscles in the Legs

Sartorius · Tensor Fasciae Latae · Rectus Femoris · Vastus Lateralis · Vastus Medialis · Tibialis Anterior · Fibularis Group · Adductor Group · Biceps Femoris · Semitendinosus · Semimembranosus · Gastrocnemius · Soleus