Skip to content

VIDEO: Here's why you need to fully extend your knees

In this week's video, Newmarket athletic therapist Jen Mark demonstrates basic exercises that will help, or prevent, knee problems

There are many instances where we might be lacking full knee extension. We lose knee extension when we suffer a knee injury and a moderate/severe amount of swelling results. Osteoarthritis can also cause a decrease in full knee extension. I have seen many people who lead an inactive lifestyle lose their full knee range of motion, as well.  

Why is full knee extension so important? You can live a very functional lifestyle without full range of motion. You might not even experience a lot of knee pain, initially. However, when our biomechanics break down, something has got to give.

If you are not fully extending your knee when you walk, you cause more stress to the structures in the knee and hip. This can cause rotations in the bones during movement as the body compensates. 

Eventually there is a breakdown somewhere in the chain. Your pelvis might be pulled out alignment causing issues travelling higher or lower in the body. The body can compensate for a long time… until it can’t. 

When there is an acute knee injury and swelling results, the muscles around the knee start to atrophy very quickly. Specifically, the vastus medialis obliquus, or VMO. This is the lower portion of the inner quad muscle. 

When you make your quad muscle tight, you should see a teardrop shape slightly above the knee on the inside of the quad. If that muscle is not activating enough, there will not be much of a teardrop. 

This portion of the muscle brings the knee into the last 15 degrees or so, of extension. If that muscle is not fully active, you will not be able to reach full range of motion, and stability of the knee is sacrificed. 

The muscles in the glutes (glute medius specifically) work with the VMO to help keep the knee stable. Tight hamstrings or meniscus damage will also cause a lack of extension as well. No matter the cause, the method is very similar. Get your range of motion back! 

The exercises in the video are basic for any knee extension problems. If you experience pain in the exercise, it’s not right for you. The exercises in the video are great for anyone who no longer has swelling and needs to get their range back. Doing these exercises before having any knee surgery drastically helps with the post-surgery recovery. 

The most basic way to test your knee extension is to press your knee into the floor while lifting your heel off the ground. Compare both sides. Can you keep your knee touching the floor while your heel lifts up? To improve the range, you can use a towel or strap around your foot to help lift your heel up when you actively push your knee down. And for further assistance, place a pillow under your knee and press into the pillow. 

Strengthening the VMO is important, as well. There are many ways to target this muscle and most revolve around focusing on the actual extension. For example, when squatting complete the movement by fully straightening your legs when your stand. 

And in the video, I demonstrate how you can place a band around the back of your knee and straighten your knee against it. The resistance of the band makes that VMO work even harder.


Either focus on these exercises to bring your knee back to health, or add a few into your regular routine to help keep your full range of motion. An ounce of prevention can certainly go a long way… especially in your knees.