As massage therapists, we often see clients with painful knees. Professionals working with knees often bandy around the term VMO as the possible cause of the pain but what exactly does it mean. It stands for Vastus Medialis Obliquus but to most of us that makes us none the wiser. The Vastus Medialis is one of four quadricep muscles that lie on the anterior of the thigh:
- Rectus Femoris
- Vastus Lateralis
- Vastus Intermedius
- Vastus Medialis
The main function of these muscles is to extend the knee, so it is fundamental in walking, running, squatting, etc but all of these muscles have unique roles in supporting and stabilising the knee.
The vastus medialis originates from the tendon of Adductor Magnus and inserts into the tibial tuberosity via the patella tendon (as do all the quadricep muscles). The oblique fibres of the Vastus Medialis have been singled out and therefore given special mention because they perform and important role in stabilising the kneecap (patella) and ensuring that it tracks properly. Weakness and mis-firing of these muscle fibres mean that when the knee is straightened, the patella doesn’t track properly in the patella groove causing painful achy knees and, over time, long term damage to the surrounding structures.
But why is the VMO consistently showing up as weak and not firing properly and how can we ‘switch’ it back on.
First of all, you must determine whether your VMO is contracting :
- Sit with your legs out in front of you and a rolled up towel under your knee (the knee should be slightly bent)
- Put your fingers over the area of VMO (as shown above right).
- Push your knee down into the towel (so that your knee straightens and the foot lifts off the couch)
- You should feel a strong contraction under your fingers
- If the muscle does not contract, continue to practice whilst pressing down gently on the muscle and concentrating on contracting the fibres underneath your fingers.
If the muscle does contract, you can continue with strengthening exercises:
- Sitting on a chair with the knees bent, palpate the VMO. Start to slowly straighten the knee and ensure the VMO contracts. Maintain the contraction throughout the movement as you fully straighten the knee and bend it again. Repeat this twice daily until you can maintain a strong constant contraction 10 times in a row.
- Place a large ball (such as a football) in between your knees and squeeze it.
- Try performing a squat against a wall by sliding your back down the wall until your knees are at a right angle (your shins should remain vertical).
- Try Peterson step ups. This exercise is difficult to explain so this demo is helpful. http://m.youtube.com/watch?v=UUYBhnN6IJA