I came across some very interesting information recently. As I was reviewing presentations that were given at this year’s annual meeting of the American College of Sports Medicine (ACSM), I found a new study regarding maximally cushioned, or “maximalist,” running shoes.
Researchers from the Spaulding National Running Center at the Harvard Medical School in Cambridge, MA, presented on their study which found that maximalist shoes may not be associated with lower impact forces in some runners. This finding is inconsistent with shoe industry claims, and some previous studies on the topic.
Due largely to midsole thickness, maximalist shoes have up to 2.5 times more cushioning by volume than a standard running shoe. They are thick, fat, and tall when viewed from the side. Kind of like the old “Chunky” candy bar that I probably had too many of when I was a kid. If I offer up an analogy, we often think of running in maximalist shoes to be like an off-road vehicle with a “soft, long-travel suspension” (due to the springs and shocks). We imagine that the material in the shoe midsole behaves like that suspension and allows us to slow down and absorb our impact loads from footstrike.
However, this new study found that impact loading forces were higher when the same runners ran in maximalist shoes than when they ran in traditional shoes. Their primary theory behind this finding is that the presence of the additional cushioning “shuts off” some of our natural, flexed, soft-landing behaviors and may cause runners to inadvertently “slam” their foot into the ground harder. Some call this a “feel” for the surface (road, track, trail, etc.). That makes some sense to me, and who am I to say the study was flawed in its design anyway? But, the point to note is that this study was a “novel” wearing experience for all the runners. They were not regular maximalist shoe wearers and were only given 3 minutes to accommodate to the shoes before the impact data was collected. My thought, is that just like any human training or learning experience, there is adaptation over time. So, going out on a limb here, my guess is that those higher impact forces may go down over time as a runner gets used to the shoe. And I imagine that, in some cases, impact forces may even eventually become less with maximalist shoes than with traditional shoes as a runner learns to run in them. The key to enhanced shock attenuation in the runner is dependent on stride, strike, and knee flexion. All these can be improved with training, and are potentially enhanced by shoe familiarization as well.
The study also noted that pronatory acceleration (the speed and ultimately the force with which the foot pronates, or flattens, when we land) tends to be greater in the maximalist shoe than in the traditional shoe. This is similar to the older versions of stability shoes that had excessively wide heels. The higher off the ground you put a lever (in this case the foot), the more force it can generate.
A related study noted that balance tends to better with minimalist shoes than maximalist shoes. That should seem obvious, as the closer the foot is to the ground, and the more firm the contact, human balance performance goes up. Put someone up in the air on a big cushion and their balance deteriorates. We have been using tests and tools in the physical therapy world for decades that utilize this principle.
One might deduce that heavier runners who strike hard, but are fairly “stable” or neutral in their amount of pronation, do best with maximalist shoes. That makes sense to me but we need to give the shoes a little more wear time in the running community and allow for more research to filter in.
The reason I argue this point is that we really need to start using our COMMON SENSE! Scientific data is ours to interpret and apply, and we should be oh-so-careful about blindly jumping into every fitness and diet trend that comes along. Manufacturers often spend more money on marketing than on research and development. Don’t believe everything you read or hear…even (gulp) if it comes from me! Try things out, but test them objectively and cautiously, whether that is a shoe, a workout, or a food.