VMO Strength Exercises

VMO strength exercises are used with most knee physical therapy programs. The VMO is an important part of balancing movement of the knee cap.  Most people with knee pain have some weakness in the VMO. But isolating the VMO for strength training is tough.

Top 3 VMO Strength Exercises

1. Quad Sets - With the knee extended, contract the muscles in the front of the thigh as tightly as possible. Hold 10 seconds, 10 X.

Image of quad contraction with label showing VMO with Quad set

2. Straight Leg Raises - Lying on your back with the leg straight and the opposite leg bent, tighten the thigh and lift the straight leg about 12 inches off the surface. Hold 3 seconds, repeat 10 x 2 sets.

image of a man lying supine on elbows doing a right straight leg raise for vmo strength exercises

3. Squat - Stand near a support surface and slowly bend the hips and knee into a squat position. Make sure the quadriceps are tightened through the exercises. Keep the knees behind the toes and keep the knees apart. Do not push through pain. repeat 10 x for 2 sets. 

MAn performing a squat with proper technique with side view and labels showing knee position and back curvatureSquat (Side View)

Read Here to learn more about Proper Squat Technique.

What is the VMO? 

The VMO or Vastus Medialis Oblique is part of the Vastus Medialis Muscle. There is debate among anatomists as to whether the VMO is an independent muscle or part of the Vastus Medialis. 

The Vastus Medialis is 1 of the 4 muscles that make up the Quadriceps. The quadriceps are the muscles in the front of the thigh that straighten the knee. The muscles come together at the quad tendon, which attaches to the patella or knee cap. 

The 4 muscles that make up the Quadriceps are:

  1. Vastus Medialis
  2. Vastus Lateralis
  3. Vastus Intermedius
  4. Rectus Femoris

Anatomical diagram of the VMO or vastus medialis oblique with arrows and labels to the components of the quadricepsVMO Anatomy

The VMO is the lower part of the Vastus Medialis that runs in an oblique direction toward the knee cap.

What Happens When the VMO is Weak?

Weakness or decreased activity of the VMO can lead to abnormal tracking of the patella at the knee. 

When the quadriceps fire properly and in the correct sequence, the patella is balanced in the middle of the groove where is sits at the end of the femur at the knee. This allows the knee cap to glide easily up and down as the knee straightens and bends. 

When the VMO is weak, the other quadriceps muscles pull the knee cap to the outside part of the groove. This can lead to rubbing and excess wear and tear of the joint surfaces in the outside or lateral patellofemoral joint region. 

What Makes the VMO Weak?

The VMO gets weak when it does not activate as much. This tends to happen when there is pain or swelling in the knee. 

Swelling inside the knee joint capsule can cause the brain to stop normal muscle activation in the quadriceps. This can affect the order or sequence that the 4 muscles of the quadriceps contract or fire. This leads to weakness and atrophy of the VMO. 

How Do You Make the VMO strong?

The VMO can become stronger with specific VMO strength exercises. It typically takes awareness and isometric exercises to activate it. 

Can You Isolate the VMO for Strength Training?

This topic has had much debate, but It is not possible to isolate just the VMO. The brain also send a message to the rest of the muscles to contract. 

There are ways to make the VMO fire better and more efficiently when tightening the quadriceps. This includes:

  • Manual Biofeedback - Place a finger on the VMO and try to make sure the muscle feels firm while contracting.
  • Electrical Biofeedback - Electrical Biofeedback is a machine that detects the electrical activity in the muscle and allows the user to tighten harder to increase the signal detected. There are usually lights or sounds that respond the the muscle activity.
  • Electrical Stimulation - Electrical Stimulation uses an electrical impulse to stimulate the muscle to contract. This is not a replacement for the normal self activated contraction but it provides sensory input to the brain to be more aware and efficient with VMO contractions.

Will VMO Strength Exercises Fix Knee Pain?

Increasing the activity of the VMO can help fix knee pain in many cases. The VMO can help to balance the position of the knee cap and normalize movement and mechanics in the knee. 

The VMO is not the only cause for lateral patellofemoral pain though. Other causes include:

  • Excessive Knock-kneed position (Genu Valgum)
  • Weakness in the Gluteus Medius 
  • IT Band Syndrome/Tightness

Both of the these issue alter the normal mechanics of the patellofemoral joint and can contribute to knee pain and dysfunction. 

Image of a patient with a weak Left gluteus medius and Trendelenberg pattern or dropped pelvis on the RWeak Gluteus Medius

Strengthening the Gluteus Medius can help to manage some types of knee pain. Click to learn how to learn the 4 Best Glute Home Exercises.

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