Exactly why Running Shoes Don’t Work

The running shoe model needs to be fixed. Pronation, motion control, cushioning, and stability shoes? Get rid of them all.

It’s not just barefoot running and minimalism versus running shoes, the either/or situation many portray it to be. It’s much deeper than that. It’s not even that running shoe companies are evil and in order to make a profit. Shoe companies may be accomplishing the goals they set out with regard to, but maybe the goals their targeting are not what need to be done. The particular paradigm that running shoes are built upon is the problem.

Running shoes are built on two central premises, impact allows and pronation. Their goals are basic, limit impact forces and prevent overprontation. This has led to a classification program based on cushioning, stability, and movement control. The problem is that this system may not have any ground to stand on. Have we been focused on the wrong things for 40+years?

I am going to start with the customary statistic associated with 33-56% of runners get hurt every year (Bruggerman, 2007). That is kind of mind blowing when you think about it. Since there are a ton of accidental injuries going on, let’s look at what shoes and boots are supposed to do.

Pronation:

As mentioned earlier, shoes are built upon the basic that impact forces and pronation are what cause injuries. Pronation, in particular has been constructed as the bane of all runners. We have become full with limiting pronation via motion control shoes. The central concept behind pronation is that overpronating leads to rotation of the lower leg(i. e. ankle, tibia, knee) putting stress on the joints and therefore leading to accidental injuries. Running shoes are therefore designed to limit this pronation. Essentially, running shoes are developed and designed to put the body in “proper” alignment. But do we really need proper alignment?

This paradigm on pronation relies on two main things: (1)over pronation causes injuries and (2) running shoes can modify pronation.

Looking at the first premise, we can see several studies that do not show a link between pronation and injuries. In an epidemiological study by Wen et al. (1997), he discovered that lower extremitly alignment had not been a major risk factor for marathon runners. In another study simply by Wen et al. (1998), now a prospective study, he concluded that ” Minor variations in lower extremity alignment do not appear conclusively to be major risk factors for overuse injuries in runners. ” Other studies have reached similar conclusions. One by Nigg et ‘s. (2000) showed that foot and ankle movement did not predict injuries in a large group of runners.

If foot movement/pronation does not predict accidental injuries or is not a risk factor for injuries, then one has to query whether the concept is sound or even working…

Looking at the second premise, do shoes even modify pronation? Movement control shoes are designed to decrease pronation through a variety of mechanisms. Most choose to insert a medial post or perhaps a similar device. In a study simply by Stacoff (2001), they tested several motion control shoe devices and found that they did not alter pronation and did not change the kinematics from the tibia or calcaneus bones either. Similarly, another study by Butler (2007) found that motion control shoes showed no difference within peak pronation when compared to cushioning shoes and boots. Lastly, Dixon (2007) found similar results showing that motion control shoes or boots did not reduce peak eversion (pronation) and didn’t change the concentration of pressure.

This is sort of a dual whammy on motion control sneakers. If excessive pronation does not cause injuries to the degree that everyone thinks, and if motion control sneakers don’t even alter pronation, elaborate the point of a motion control footwear?

Cushioning:

Impact forces are the additional major scoundrel of running injuries. The thinking goes like this, the greater the impact force on the reduce the leg, the greater stress the foot/leg takes, which could potentially result in injuries. To combat this worry, running shoes, particular cushioning ones, are usually to the rescue. Let’s take a look.

The first issue is, do cushioning shoes get the job done?

Wegener(2008) tested out the Asics Gel-Nimbus and the Brooks Glycerin to see if they reduced plantar pressure. They found that the shoes did their particular job!…. But where it decreased pressure varied highly. Meaning that pressure reduction varied between forefoot/rearfoot/etc. This particular led to the interesting conclusion that will their should be a shift in prescribing shoes to one based on where plantar pressure is highest for that person person. It should be noted that this decrease in pressure was based on a comparison to a different shoe, a tennis shoe. Now i’m not sure that this is a good control. Essentially, this study tells us that cushioned running shoes decrease peak pressure when compared to a Tennis shoe.

In a review on the subject, Nigg (2000) found that both external and internal influence force peaks were not or barely influenced by the running shoes midsole. This means that the cushioning type does not alter impact forces much, if at all. But how can this be? I mean really common sense if you jumped on cement vs . jumped on a shoe foam like surface, the shoe surface area is softer right? We’ll come back to this question in a minute.

Effect Forces: The picture gets cloudier:

But it’s not as simple as defined above. In an interesting study simply by Scott (1990) they looked at top loads on the various sites of likely injury for runners (Achilles, knee, etc . ). All top loads occurred during mid-stance and push off. This led to an important finding that “the impact force from heel contact was estimated to have no effect on the peak power seen at the chronic injury websites, ” and led to speculation that will impact force did not relate injury development.
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Further complicating the effect force idea is that when looking from injury rates of those running on hard surfaces or soft areas, there appears to be no protective benefit of running on soft surfaces. Exactly why is this? Because of something called pre-activation and muscle tuning which will be discussed below.

Supporting this data, some other studies have shown that people who have a low peak impact have the same likelihood of getting injured as those with a higher peak impact force (Nigg, 1997). If you want to complicate things even further, influence seems to be the driving force among increased bone density.

As a trainer or trainer this should make sense. The particular bone responds to the stimulus by becoming more resistant to it, IF the incitement is not too large and there is sufficient recovery.

Underestimating our Body: Impact causes as feedback:

Back to the question I actually asked earlier: How can impact forces not change based on shoe single softness and why isn’t operating on hard surfaces lead to a lot more injuries?

The problem is, once again, we underestimate the human body! It’s an amazing thing, and never give it the credit this deserves. The body adapts to the surface area that it’s going to strike, if you give it a chance. The body adapts to both shoe and surface adjusting influence forces via changes joint stiffness, the way the foot strikes, and an idea called muscle tuning.

An example of this is often seen with barefoot running, the diminished proprioception (sensory feedback) of wearing a shoe negates the padding of the shoe. Studies using minimum shoes/barefoot have shown that the body appears to adapt the impact forces/landing depending on feedback and feedforward data. Whenever running or landing from a leap, the body takes in all the sensory details, plus prior experiences, and changes to protect itself/land optimally As mentioned above, it does this through a variety of mechanisms. Thus, you stick some padded running shoe on the bottom of your feet and the body goes “Oh, jooxie is okay, we don’t need to worry about influence as much, we’ve got this soft bit of junk on our foot.

One idea that needs to be further discussed is muscles tuning. It’s a concept recently proposed by Nigg et al. within 2000. He sees impact force as a signal or a source of suggestions, as I stated earlier. The body then uses this information and adjusts accordingly to minimize soft tissue vibration and/or bone tissue vibration. His contention is that influence force is not the problem, but rather the signal. Muscle tuning is essentially controlling these vibrations via a variety of methods. One potential mechanism is pre-activation. Pre-activation is activation of the muscle tissues prior to impact. In this case it is a way of muscle tuning to prepare for impact and in addition can alter muscle mass stiffness, which is another way to prepare for influence. Pre-activation has been established with multiple EMG studies.

Shoes not only influence this, but surface type does as well. As mentioned previously, the change in running surface did not impact damage rates. Why? Probably because the entire body adapts to running surface. Within an interesting study measuring muscle action, O’Flynn(1996) found that pre-activation changed based on surface. To prepare for effect, and presumably to minimize muscle/bone oscillation, when running on concrete pre-activation was very high, when running on the soft track, not so much.

What all this means is that the body adapts via sensory input. It has several different adaptation methods. A shoe influences just how it adapts. The shoe is not doing anything to alter cushioning, it is simply altering how the body reacts to impact. It’s a significant attitude jump if you think about it. Here’s the summary: The type of shoe and materials of the shoe changes impact NOT REALLY because of alignment of the lower lower-leg or because of changes in padding. Instead it changes impact characteristics because it alters the sensory comments.

In conclusion on the cushioning concept. Nicely, what are we trying to cushion? Heel impact forces have not been shown to relate to injuries, in fact in one research low impact runners had a 30% injury rate compared to a 20% damage rate in high impact runners. Footwear midsoles do not change, or partially change impact forces anyway. Therefore , not only may cushioning not be the answer, the shoes might not even be carrying out their job. But what about all those shoe cushioning studies showing improved cushioning with their new midsole?! Nicely, the majority of that testing is done by using a machine to simulate the impact forces that you experience during operating. That means, yes it may cushion a direct effect more, but it doesn’t take into account the function of the body adjusting impact based on feedback.

The reason cushioning doesn’t work? Because the body adapts based on feedback and feedforward information. These results motivated one notable researcher(Nigg, 2000) in order to call for the reconsideration of the padding paradigm for running shoes.

Barefoot running?

Quickly, this topic could not be complete without a brief mention of barefoot running. An interesting thing to note is that the initial peak impact force is definitely absent in barefoot running in comparison with running with shoes. What this means is that, the impact forces look like (A) for shoes and (B) for barefoot. That initial little blip in A is the initial impact power. There is a hypothesis that this initial effect force is related to injuries.

A recent study by Squadrone et al. (2009) compared running shoes, barefoot running, and running in Vibram Five Fingers. They will demonstrated reduced impact forces, shorter ground contact and stride size, but increased stride frequency while running barefoot (and in Vibrams) as compared to running with shoes. This is not unexpected, but shows that running shoes fag fact alter our normal strides. An interesting point is the reduction in step length but increase in stride frequency. Shoes tend to promote this longer stride at a consequence of ground contact times and frequency. This happens because of changes in feedback signaling, increased likelihood to land upon heel stretched out, increased weight, all of these lead to longer times on the ground. Really interesting to note that elite runners all have short ground connections and high frequencies (as exhibited by the often quoted Daniels study of 180 strides per minute).

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