What Do We Mean By Knee Drive?
Your knee drive starts as a response to your foot hitting the floor – the more power your foot puts through the floor, the higher your knee will want to rise up (remember ‘each action has an equal and opposite reaction’ from this blog post on arm drive in running). The hip then carries this momentum forwards by driving the knee forwards. It’s important to focus on driving the knee forwards, rather than upwards, as that’s the direction you want to go.
Why Is Knee Drive Important For Runners?
There are two ways you can change your stride to become a faster runner; increase your stride speed or increase your stride length. Knee drive plays a part in both.
Every millisecond your foot is in contact with the ground, it contends with frictional forces which slow you down. Increasing your stride length will reduce the number of steps you have to take and the overall contact time you have with the ground over the course of a run. How do you increase your stride length? Increase your knee drive. This will turn you from a ‘shuffler’ into a runner.
Speed is generated through pushing a downward force through the floor. It’s much easier to run quickly on the road than through soggy mud as it’s very difficult to get downward force on a soft surface. When you see a cross country runner run through mud you’ll see them lifting their knees higher. This higher knee lift gives their foot a greater gravitational force to use as it drops to the floor. Whatever the surface, the higher the knee lift, the greater the force as the foot hits the floor and the faster the leg moves forward. However, there is a limit to this: You’ll notice that elite sprinters will raise their knees to an angle of up to 90 degrees to the vertical so they can put a greater power into the floor. Of course, this isn’t sustainable for a long period of time so elite distance runners will raise their knees to about 45 degrees, even when running on firm ground. This higher knee lift has the added benefit of gravity taking some of the work of running off the runner.
Don’t let that previous paragraph put you off; it’s unlikely that you’re near that 90 degree angle! If you’re not sure, have someone watch you do some 70% effort strides and gauge your maximum angle of knee elevation. If this is lower than 45 degrees, work on your knee drive.
What Are The Potential Risks Of Neglecting Knee Drive?
Trying to increase your stride length without working on knee lift has definite risks. If you purely focus on striding further, you run the risk of your foot hitting the ground in front of your body, which has a braking effect and will jar your leg, causing stress to the foot, ankle, knee, hip and lower back. Likewise, if you focus on putting a greater force through the ground without working on knee drive properly, you’ll end up ‘stomping’ which will also put you at risk. Your best bet is to use a knee drive programme constructed for distance runners. This will give you a faster, longer stride without you trying to reach forward with your feet or push them harder into the ground.