One of the blogs that I love to follow is The Gait Guys.  To really dig into their content, you really have to be comfortable with distinguishing the sagital, transverse, and frontal planes, know your flexor hallucis brevis vs your flexor hallucis longus muscles, and a whole lot of other technical stuff.  Recently they posted their thoughts on Hoka One One running shoes and other “maximalist” running shoes.  Bottom line: think twice before you buy them.  Here’s the simplified explanation about why.

Greater Risk of Injury with Maximalist Shoes

Those maximalist shoes may feel great with their giant cushy midsoles– and your body thinks so too.  So much in fact that it lets down its guard and actually puts you in danger of more injuries than you may have had with less cushiony shoes!  “How can that be?” you may ask.  Well, your body does a great job at cushioning impact when running.  For instance, it does this by slightly bending at the knee on impact or enabling a little give in some muscles to allow the ankle joint, for instance, to have a little springiness.  It’s a complex shock absorption system that involves the entire lower body– and accounts for just about every running injury out there.  Everything from plantar fasciitis to shin splints, from calf strains to knee pain– all of them typically find a home in one of the myriad of shock absorption mechanisms that your body has developed over millions of years to cope with the stresses of running upright on two legs.  But, when you think about it, those strategies your body uses are exactly the opposite of what your body would do if it needed more stability and rigidity– say because your body thought that you were walking on an unstable surface.  Stability and shock absorption are the yin and yang of running.

Well it seems that Hokas and other over-cushioned running shoes disrupt that yin-yang balance for your body.  First, the extra cushioning doesn’t feel as stable to the body– and your body responds by increasing rigidity and decreasing shock absorption.  Second, your body feels that it’s safe to lower it’s guard because the impact forces “feel” so much lower.  In other words, all those self-preservation cushioning mechanism that your body uses go right out the window.  All that would be fine except for the fact that running shoe midsoles don’t provide the level of cushioning that your body thinks it provides– particularly after only a few runs.  No matter what the running shoe companies tell you, that cushioning breaks down fast.  This adds up to a much bigger injury risk.  In a separate blog article, the Gait Guys talk more specifically about this counterintuitive result and back it up with some research data.

There’s Cushioning and Then There is Cushioning

One of the points mentioned in the studies is that insole cushioning may be more directly felt by your body than midsole cushioning.  Same goes for shock-absorbing heel pads.  It isn’t as clear from the research that these devices cause the same level of destruction as highly-cushioned midsoles.  My suspicion is that these cushioning strategies are safer than relying on a big cushy midsole.  First, the studies cited by the Gait Guys focused on EVA– the material found in almost all running shoes.  Because EVA is just foam, it is prone to have the minute air bubbles collapse and thus lose cushioning.  The material in insoles, however, typically isn’t foam and probably won’t suffer breakdown as easily.  Second, and more importantly, is the stability factor– big thick midsoles introduce the possibility of a lot of instability, which is the most significant cause of reducing the body’s impact-absorbing mechanisms.  Insoles are pretty thin and shouldn’t cause the same instability.

A big question that I have is “what about running on an Alter-G?”  If you’re coming off a significant injury (e.g. Achilles tendinitis, stress fracture, etc), I think you’re foolish if you don’t try to find an Alter-G treadmill in your area that you can run on.  Mind you, I’m not suggesting that you buy one of these $30,000 treadmills– there are plenty of physical therapists and others who will happily rent you time on one (to help recoup their investment costs).  Alter-G treadmills do a great job at reducing impact on the body by using air pressure to lower your effective body weight.  I love Alter-G treadmills, particularly as I get older, because they are much easier on the body.  But I have noticed that I am much more prone to blisters in my forefoot when running on them.  I suspect that my body may be more lax in its impact-reducing mechanisms because of the extra cushioning provided by the Alter-G.

The Pendulum is Swinging Around Again

Minimalist shoes have been taking a bad rap recently, particularly in light of the Vibram Five-Fingers lawsuit.  So the pendulum swung the opposite way and lots of shoe companies are abandoning their minimalist shoe lines in favor of massive “maximalist” shoes.  I’m glad to see that forces are at work to make sure that they don’t go too far.