Sunday, April 28, 2013

Minimalist running shoes: Are they really what we want them to be?

Like many I began to think about so-called minimalist running after I read Christopher McDougall's Born to Run, which tells the story of the seemingly superhuman Tarahumara Indians and their ability to naturally run for miles (and essentially barefoot). Similar to what the Paleo diet has done in nutrition circles to reinvigorate an ancestral perspective with nutrition (to essentially think of nutrition or diet composition as something that should be strongly informed by what our ancestors ate thousands of years ago), McDougall's book sheds like on running from the perspective of human evolution.

Around the same time the book came out in 2011, discussions about barefoot running really started to take off and contributed to the serge of minimalist running shoes that came onto the market. (Many of the major running shoe brands now have at least one minimalist option.) A 2012 study in the Journal of Strength and Conditioning Research found that about 75% of more than 6,000 runners surveyed said they were "at least somewhat interested in running barefoot or in minimalist shoes."

So what's all the hype about? Why are so many people interested in minimalist running shoes?

More and more research is pointing to several benefits from barefoot running, such as fewer injuries or better performance. This study found runners in minimalist shoes or barefoot were 2-3 percent more economical while running on a treadmill than running in standard running shoes, likely due to improved "elastic energy storage and release in the lower extremity during minimal-shoe running." Comparing injury rates between runners wearing minimalist shoes (or running barefoot) and those wearing traditional shoes, other researchers found an injury rate 3.4 times higher in those wearing traditional shoes.

The basic argument for increased injuries when wearing traditional running shoes has everything to do with the biomechanical differences in foot strike. As I've discussed previously, when heel striking the equal and opposite force that is generated sends a shock to the ankle, knee and hips. Conversely, during a forefoot strike (which is more common with barefoot and minimalist runners), there is a much smaller impact force that's generated. For those interested in exploring this more, I highly recommend the above link on biomechanical differences in foot strikes. Looking back at the 2012 study of 6,000 runners I just mentioned, injury prevention was the most common reason for choosing to run barefoot or in minimalist shoes. More than a third of those running barefoot or in minimalist shoes said it was prevent future injury.

But, for some of the benefits, there are certainly some risks, particularly for those making the transition to minimalist/barefoot running after years or decades of running and walking in traditional shoes. In Lore of Running, Dr. Tim Noakes writes "only those with perfect biomechanical function were able to survive training; those with less than perfect function were soon injured and dropped the sport. Today, many runners who have very bad biomechanics are able to run prodigious distances only because of the very real improvement in the design of running shoes. In the past, they would simply have had to stop running because of recurring injury."

In fact, there has been research to suggest that many of the benefits of barefoot running are in those who have consistently trained their feet and surrounding musculature to adapt. The main take-away - if you're interested in running barefoot or in minimalist shoes, it's going to take time. More on this later.

I'm personally about a year into the process of transitioning to more minimalist running (for all the reasons I've already discussed).

I went from running in these about 18 months ago...
To these about 6-12 months ago...

And began running in these about 4 months ago...

But one of the interesting questions - and one that isn't addressed often in the literature - is if minimalist running shoes actually does a good job of simulating barefoot running from a biomechanical perspective. There's plenty of evidence showing a clear difference with traditional running shoes, but studies often lump minimalist running shoes into the same category as barefoot running. The big question this a good assumption?

Well, taking a look at a study from earlier this year published in the British Journal of Sports Medicine suggests it might not be. Researchers looked at the 3-D kinematics at the hip (top panels), knee (middle panels) and ankle (bottoms panels) joints for the stance phase of the gait cycle (this is when the foot is in contact with the ground) of four different shoe types: barefoot, minimalist, racing flat, and traditional running shoes.

Here is a breakdown of what they found...

It's slightly difficult to interpret because the graph is a little small, but here are two main points.

First, you'll notice that much of the kinematic variation is at the ankle and knee, and much less so at the hip. Barefoot runners showed a reduction in peak power generation at the knee, but an increase at the ankle compared to all other running types. You basically have a shift in the joint being stressed when barefoot running from the knee to ankle. This is, in my opinion, one of the important reasons for a gradual transition if you're thinking about dumping those regular running shoes and hitting the pavement barefoot.

As I mentioned before, it takes time to build the necessary foot and ankle strength to accommodate barefoot running (or minimalist shoes in some cases). By making the transition too quickly you run risk of injury. This is even the case when transitioning from traditional running shoes to more minimalist shoes. Start by spending more time walking around the house barefoot, or introduce one workout a week in more minimalist shoes. Over time and with increased strength in the foot, ankle, and calf, you'll be able to slowly build volume.

Second, kinematic analysis showed that the joints examined tended to act more alike in minimalist, racing flats, and regular shoes, compared with barefoot running, which had it's own unique kinematic profile. So, what does that mean? Well, essentially, there isn't too much of a difference between regular running shoes and minimalist shoes from a kinematic perspective, despite all the marketing claims. (One word of caution: this study looked only at one particular type of minimalist shoes - the Nike Frees - and didn't necessary look at all commercially available minimalist shoes, such as those from New Balance, Saucony or Brooks.)

So, if the hope is to mimic barefoot running by buying a pair of minimalist shoes, you might just want to slowly ease into the real thing. As much as we'd like minimalist running shoes to give us the same experience as running barefoot; well, that simply might not be the case. And if you're hoping to improve your biomechanics, you might get a higher bang for your buck by focusing on running technique and drills instead of dropping a hundred bucks on a new pair of kicks. Recalling the mantra of running coach James Dunne - form before footwear!

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