Kevin's Drop of Knowledge Pt 3

Foot, Ankle, and Hip Function Part 3

Heel Lift and cushioning

Welcome back to our blog series on foot, ankle and hip function. Today, I will be talking about heel lift and cushioning in modern shoes and how it affects your posture, ankle range of motion and running gait.

Most of us know that high heels are not good for your back or posture. Many of us don’t know that this applies to all modern shoes, even though the heel height is not as noticeable. In the first part of this blog series, I discussed the feet being the foundation of our bodies. A good analogy would be a building sitting on an uneven foundation, even an inch or two of angle, as you build up the height of that structure it gets exacerbated and will throw off the center of gravity, resulting in an unstable structure. The same happens with your feet. Where your heels are relative to your toes has a major impact.

Using this same scenario, if you were to maintain proper posture from your ankle to your head with an inch or two of lift under your heels your centre of gravity would be moved forward and your head would now be over or passed your toes. This depends on the height of the lift. As you can imagine, it would be pretty hard to stand on your feet if that were the case.

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Then why can we wear a heel lift/high heel? It is because we have joints that can move to accommodate that change in our centre of gravity. Our ankles, knees, hips and spine have to make a posture adjustment to keep you upright. The more time you spend with elevated heels over a lifetime will affect the range of motion and the wear and tear on some of your joints.

Let’s begin with our ankle joint. With our heels elevated, it puts our calf muscle into a shortened position. Over time, the calf muscle will maintain that shortened position. Our foot is now in a slightly plantar flexed position, making it hard for us to spend time with your heels down. It also affects our ankles’ ability to dorsi flex (flex your foot up towards your shin).

 It is extremely important to maintain your ankle joint’s full range of motion. Without a healthy amount of dorsi flexion, it greatly impacts our ability to squat, walk, run, walk upstairs, walk up hills, or get up from the floor without putting extra stress on your knees.

As we move up the body, the knees have to flex slightly to maintain posture and like we mentioned above they are also taking on more stress. Going to the hips, the pelvis has to tip forward to keep your centre of gravity balanced over your feet. This is where some low back problems come from.

 With an anteriorly tilted pelvis, we are extending the lumbar spine. These postures, over time, are what leads to the wear and tear on joints and end in pain and surgeries.

It is extremely important to expose your body to walking, running, and moving on a variety of surfaces: soft and hard, inclines, declines, sideways and backwards. Many problems come from chronic exposure to one form of movement, posture, position without offsetting those movements with opposite or competing movements, postures or positions. We need to cut down the time we spend standing and walking on these ramps we call shoes.

Now on to cushioning. The main purpose for cushioning in our shoes is to cut down on the impact forces traveling through your heel as you land with each stride. When walking, the amount of force that travels up your leg is between 2-3 times your body weight. While running, it can be anywhere from 5-12 times your body weight. These are large forces, and the idea to use cushions to lessen these forces sounds like a good idea, but is a little flawed in its execution.

When it comes to running, modern shoes that elevate the heel with cushioning actually force the runner into a gait that requires the heel to strike the ground first with every stride. The issue here is that the heel is not designed to take the large forces of running. If you were to sprint barefoot or in a minimalist shoe and use a heel strike, your heels, knees, and hips would be compromised very quickly.

How did humans run before cushioning? We ran landing each stride with a midfoot or forefoot strike.  My first blog post stated that our feet are complex so that our shoes don’t need to be. The human body has already engineered great shock absorbers into the design of our feet and legs. These shock absorbers are your foot arch, Achilles tendon, calf (gastroc and soleus) muscle, and the deep flexors of the lower leg.

When you land with a forefoot or midfoot strike, the tissues of the plantar fascia, muscles and tendons that form your arch, stretch and start to cushion the impact. As your heel starts to lower to the ground, that movement is controlled by the big, strong calf muscles via the Achilles tendon. These stretched elastic structures then store energy, ready to propel you forward like a spring, into your next stride.

As you can see in the picture below, the differences in the forces at impact of a heel strike compared to a forefoot strike. With the heel strike (fig.a), there is a large, rapid impact. The slower, gradual force at impact is seen with the forefoot (fig. c). The heel strike, with a cushioned shoe, does little to lessen the initial rapid spike at impact (fig.b). The rapid spike of force at impact contributes to the wear and tear on knees and hips of runners, which can be exacerbated by other factors such as poor running technique and under conditioned tissues.

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When it comes to walking, landing with a heel strike is the natural pattern. The heel should be gently placed and smoothly rolled forward onto the forefoot through the stride. There is a pad of fat under our heels that helps to absorb shock and distribute the forces sustained by walking.

One of the comments that often come up about running/walking barefoot or in minimalist shoes is that we walk or run on concrete which is a much harder surface than what people used to run on prior to modern technology. Here is what I would say to that:

Humans are able to inhabit a diverse range of environments around the world because of our capacity to adapt to our environmental stressors. Humans have lived on rocky mountain ranges, sandy hot beaches, Arctic ice, the Sahara Desert with compacted dry dirt similar in hardness to concrete for thousands of years. Humans not only survive, but thrived in these areas with little more than a piece of leather strapped to their feet. These people were not hobbling around in pain, barely getting by because they didn’t have expensive brand name shoes on. They were arguably in better shape than most athletes today. We must realize that humans evolved while living outside and many still live outside in the wild with every other animal on this planet. We have the ability to move as easily, gracefully, and effectively as all other species of the animal kingdom do. We do not need advanced technologies to help us navigate the surfaces that humans have historically been able to successfully.

Secondly, the ground is as hard as your interaction with it. If someone were to stand on a box and jump off onto a padded floor, they would likely take fewer precautions with their landing, thinking that the padding would protect them. This thinking can actually lead to bad mechanics and landing harder, increasing risk of injury.

If that same person jumps off that same box knowing they are landing on a cement floor, they will instinctively try and land as softly as possible and minimize the impact to prevent injuries. This shows that if you move around mindlessly, have poorly functioning feet, and weak legs and hips, then any surface you move on, hard or soft, is going to be jarring, and can lead to injury. Someone who has strong, well-functioning feet, who moves efficiently, and is mindful of the ground they are interacting with, will walk, run and jump on any surface with relative ease and grace. This is a good lead into our next blog post called:  Your feet are sensors, so stop wearing blind folds on your feet.

Note:

I'm not here to convince you to be a barefoot runner, or live a completely barefoot lifestyle. By no means do you have to. I do neither of these. My goal with this information and my upcoming class is to educate you on the importance of healthy foot, ankle and hip function and what may compromise those functions. With this information you can then decide for yourself when to wear or not wear shoes and what type of shoe you may be willing or not willing to wear knowing the benefits or harms that may come with your choice.

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