Why Your Knees Matter
With each stride, the knee must repeatedly bend, support your body weight, and straighten as you move over the ground. The muscles around your knee work to control your body as you land. As you move through this landing phase and prepare to push off the ground, these muscles also help support and propel you forward.
Because this happens thousands of times over the course of a run, the knee needs both strength and endurance. Strong quadriceps, hamstrings, and other muscles surrounding the knee help control how the joint responds to each step and allow it to tolerate the repetitive loading that comes with running.
The goal is not to have "perfect" knees or perfect running mechanics. The goal is to build enough strength and capacity to tolerate the demands you place on your body.
The exercises below are a sample of an overall knee strengthening program. I've provided four exercises that target different aspects of strength and control around the knee, but they are not a substitute for individualized care.
The muscles of the knee
There are about 12-13 muscles that surround the knee that play a role in running performance and stability.
Watch in the video - when the foot touches the ground how the knee bends to absorb force, and then how it extends to produce force forward.Note that the knee does not bend a lot when the foot is on the ground during flat running. When the knee does bend, it stops at a certain point instead of continuing to bend, and quickly reverses to extend and assist with push-off. The fact that it does not bend a lot during flat running speaks to its primary role in providing stability, rather than push-off. The muscles around the ankle and the hip are more of the dominant contributors toward generating power with each stride.
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The exercises below are designed to help address weakness, improve local joint endurance, and reduce pain.
Specificity is essential for achieving the maximum result.When performing resistance exercises, control the weight or resistance throughout the entire movement. Avoid rushing, bouncing, or relying on momentum.
Perform both the upward and downward portions of each repetition slowly and with precise technique.
As a general guideline:Upward phase: 2-3 seconds
Downward phase: 4-5 seconds
Focus on maintaining good form and controlling every part of the movement. The goal is not simply to move the weight, but to build specific muscular support and local joint endurance that carry over to running.
When you can complete every repetition with good control and could perform three or more additional repetitions, increase the resistance slightly.
Movements
1. Single-Leg Knee Extension using a machine or ankle weight
Targets: Quadricep strength and endurance
This is the single best way to isolate and strengthen only the quadriceps. In order to maximize the benefit, you must perform this exercise slowly and with control. The knee must be fully extended at the top of the movement and held for 4-5 seconds before lowering the weight back down. This will ensure maximum development of the vastus medialis muscle, which is the major key to a sound knee.
Build up to 3 sets of 6-8 reps on each leg. If you are unable to perform a full range of motion (full extension to full bend), start with a lighter weight.Again, the knee must be fully extended at the top of the movement and held for 4-5 seconds before lowering back down with control.
2. Hip Abduction using an ankle weight, band, or during a Side Plank
Targets: Glute medius and hip control
When it comes to the knee in distance running, the glute medius is the single most important muscle to prevent the knee from collapsing inward, which is a common mechanism for knee pain and injury. Strengthening the glute medius will help control the knee during running and ensure that power is projecting your body forward rather than wasting energy by allowing the knee to collapse inward.The video below is the best way to isolate the glute medius. Sidelying position. Isolating the glute medius will help your body learn what muscle to feel when your foot strikes the ground during running.
There are three extremely important principles that many people miss to ensure when performing ANY exercise to strengthen the glute medius:
1. Ensure the hip is turned inward. You can ensure this by keeping your foot inward. It is circled in the video.
2. Ensure that the ankle is directly positioned below your hip, as opposed to being positioned in front of it. See in video.
3. Lastly, make sure the knee is locked out in full extension so no other muscles can contribute to the movement.
Build up to 3 sets of 6-8 reps on each leg.3. Single Leg Hamstring Curl using a machine or a towel or slider
Targets: Hamstring strength and endurance
Strengthens the hamstrings which assist with controlling the knee during running. They also prepare the leg for foot strike. With weak hamstrings, your knee will struggle to maintain proper alignment, and will expend unnecessary energy towards maintaining alignment rather than projecting your body forward.
One note about performing hamstring exercises: Make sure to keep your foot pointed down. Keeping the foot pointed down will ensure that the calf muscles don't try to help out with the movement.
If no machine is available, you can perform the exercise using a towel as shown, and if that is too difficult, aim for a partial range of motion.
Build up to 3 sets of 6-8 reps on each leg.1. Single-Leg Heel Raise Off a Step
Targets: Calf strength
The calf muscle are the most significant contributors towards absorbing and producing force with each stride. Building calf capacity can reduce the amount of work the knee must manage during landing and push-off.
Build up to 3 sets of 6-8 reps on each leg. If you are unable to perform a full range of motion, start with partial range and gradually increase as your strength improves.