Running with the unproven but often promoted "forward lean" (part 1 of 2)

At the peril of being very tedious and detailed, I’m posting to point out a fact of running mechanics: Small factors in one area of the body can make a big change in a different area of the body – for better or worse. Changing your running mechanics is not something to do on a whim or without proper guidance.

“John Doe” (I came up with that alias all by myself) came into my office for a gait analysis. He is a good runner and has qualified for Boston a couple times. We videotaped him and he was doing some things that should be corrected, but overall, his mechanics weren’t too bad.

After watching the video of him running, he brought up the topic of his leaning backward running style. While I think he would be better served by not leaning backward, there were more important issues to address (on the front to back camera angle) and I was reluctant to change his slight backward lean because I didn’t want to throw too many new things at him. We discussed that if he wanted to, he could lean forward a bit and that would probably get him back to straight upright, but it was really not a big deal for him. There were other priorities that needed work, so we went over drills and exercises to fix those bigger problems.

A couple months later, we re-evaluated his gait (green shirt is original gait, orange shirt is new gait). When we looked at the front to back video, the things that needed fixing were doing much better, however he had been attempting to lean forward. So, from the side view…

As the video above illustrates (you can enlarge the video if you want), he is now worse off, simply because he overdid the forward lean and is now more forward than straight vertical. The two major implications for him are:

1) His trail leg is now delayed in swinging through. This is very important for a couple reasons, but first we need to talk about why it’s delayed. Without getting TOO boring, here we go: When you bend forward, you tilt the pelvis forward which alters the position of the hip, but also you put slack in the hip flexors (the muscles that pull the thigh forward), that means that when your leg has swung backward after toe off, there isn’t as much tension in the hip flexor tendons as when you are upright. As with all joints, you can get better force development if there is a bit of elastic recoil from the muscle/tendon units. It’s the same idea with jumping – to jump higher, you first bend your knees and ankles to develop a “pre-stretch” in the muscles/tendons then you release the built up elastic energy and jump up. In the scenario of “John”, because he’s bent forward, there is much less elastic tension in the hip flexors. This delays the speed of the swing through. On the other hand, if you are upright, there is enough “pre-stretch” in the hip flexors that when the muscles start to contract, they immediately develop tension and are assisted by elastic recoil.

Why is this important? Well, in the floating phase of running, there is a scissor-like reflex motion in the legs that cause the leading leg to pull back as the trail leg pulls forward. If the leading leg is pulling back slower, you have less power propelling you forward. According the their book Running: Biomechanics and Exercise Physiology in Practice, Bosch and Klomp state: “This scissor movement is nothing more than a combination of the stumble and inverse-extension reflexes. In other words, the bending of the hip and knee of one leg strengthens the extension in the other hip and knee and vice versa…the movement of the trailing swing leg ‘chases’ that of the leading leg involuntarily.” So in other words, if the trailing swing leg is brought forward too slowly, the leading leg will have to wait, so to speak, and the pull back of the leading leg will be delayed and slower.

2) His knee is straighter at initial contact. Reduced bend in the knee at initial contact results in a decrease in the ability for the body to properly absorb shock (shock attenuation). This is self evident, but I will explain anyway: Imagine dropping a straight broomstick handle vertically on the ground. There isn’t any shock absorption. However, if there is a bend in the stick, it can better absorb shock. Not surprisingly, studies confirm that when runners make initial contact with a bent knee, there is better shock attenuation. (found here and here)

So, this runner has now potentially created reduced efficiency and increased risk of injury, simply because he “thought” he should lean forward.
There is quite a bit of chatter on the running blogs about posture. Chi Running, Pose Method, Evolution Running…they all promote a forward lean from the ankles. Frankly I don’t agree with this. Mainly because as “John” demonstrated (and many others runners I have worked with before him), runners usually make the “forward lean” from the waist and this causes problems. More on this in “part 2”.

Below, I have included a video from the 2012 Olympic marathon trials as an example. How many of these runners are leaning forward? Obviously, there are “outliers” (people who don’t fit the norm) and they have their reasons. However, the women in this video are all straight upright, with Kara Goucher maybe even leaning back a bit. (sorry about the quality, it was the best I could pull off the web)

Stay tuned for part 2 of this article…