New research compares runners’ biomechanics when training exclusively in maximalist trainers versus traditional shoes.
While trends in the running shoe industry ebb and flow, maximalist trainers seem to be here to stay. It’s easy to understand their appeal: The plush cushioning in a pair of Hokas, for example, is comfortable and provides an ample buffer from the ground, offering the reassurance—whether warranted or not—that the shoes are “protecting” our feet more than those with thinner soles.
But the claim that the super-cushioned trainers really shield us from overtraining injuries is hotly debated, and recent research has only added to it.
According to earlier research from Oregon State University, runners actually absorb more of the impact forces of running when they wear maximal trainers versus regular shoes. In that study, the researchers compared the biomechanics of 15 women when they ran a 5K on the treadmill in maximal shoes (Hoka One One Bondi 4) and traditional shoes (New Balance 880).
While wearing the Hokas, the runners recorded greater vertical loading rates (the speed at which impact forces affect the body) and peak impact forces (the maximum amount of force incurred at one time) than when they wore the New Balances.
One potential reason for the greater impact in the maximalist shoes, the earlier research noted, was that runners change their biomechanics while running in the cushy shoes.
Now, in a new follow-up study published in the American Journal of Sports Medicine, the same research group hypothesized that if runners train regularly in maximalist shoes—rather than just wearing them for a single testing session—their biomechanics would adjust so that their legs would absorb less impact over time.
In the study, 28 participants (ages 18 to 45 years old, who ran at least 15 miles per week and hadn’t been injured in the last six months) were asked to do two 10-meter running tests: one wearing maximalist shoes (Hoka Bondi 5) and one wearing traditional shoes (New Balance 880v2). During the tests, participants’ average vertical loading rate (AVLR) and vertical impact peak (VIP) of the vertical ground-reaction force (vGRF) were recorded.
After performing this session, the participants—who were all rear-foot strikers—continued wearing the maximalist shoes for the next six weeks, gradually increasing the amount they wore them until they were running all of their mileage in Hokas. When this acclimation period was over, the runners came back to repeat the 10-meter running tests in maximalist and traditional shoes.
The results? After the six-week acclimation period, the runners’ biomechanics stayed the same while wearing both types of shoes. This meant that they made no form corrections—such as changes in foot strike or leg acceleration—to reduce the amount of impact their legs absorbed.
Additionally, the researchers found that the Hokas caused greater impact forces and loading rates than the New Balances both before and after the six-week period. Why do these forces matter? Well, common sense tells us that the more the impact our legs and feet absorb, the higher our injury risk.
But here’s the tricky part: While the load may be greater overall in maximalist shoes, it’s absorbed by different body parts than more minimal shoes.
“We’re probably not lowering injury rates with different shoe types, we’re just choosing different injuries,” Richard Willy, Ph.D., a physical therapy and rehabilitation science professor at University of Montana who was not involved in the study, told Runner’s World.
Since recent research has shown that running in maximalist shoes alleviates pressure from the feet, Willy explained, these shoes can be incredibly helpful to runners who struggle with foot injuries such as metatarsal stress fractures, plantar fasciitis, or heel pad atrophy.
But runners with knee issues might want to avoid maximalist shoes, as knee loads might be higher in these. On the opposite end of the spectrum, minimalist shoes increase loads on the 4th and 5th metatarsals, plantar fascia, and Achilles tendon, but they reduce loads on the knee, Willy says.
“No shoe has ever been shown to reduce or increase overall injury risk,” Willy said. “We need to be really careful in saying that a new shoe paradigm is going to reduce injury rates just because previous shoe types have not had an influence on injury risk.”
The study didn’t find enough evidence to recommend or warn against using maximalist shoes. What runners can take away from this study, however, is that no matter what shoes they wear, their biomechanics won’t change while wearing them. So if your shoes are aggravating an injury, they’ll probably continue to aggravate it as long as you run in them.
“If the goal is to reduce impact during running, it seems that there is likely a ‘sweet spot’ for cushioning in shoes,” Willy said. “The cushioning sweet spot is probably highly individual, but like most things, moderation [in regards to cushioning] is probably key.”
“[Maximalist] shoes may work for certain people, but right now we just don’t know who they are good for,” Christine Pollard, an associate professor of kinesiology at OSU-Cascades and a co-author of the study, said in a press release about the research. “The findings suggest that people aren’t really changing the way they run in the shoes, even after a six-week transition, potentially leaving them at increased risk of injury.”