Peruse the many claims and enthusiastic endorsements of "maximalist" running shoes like Hoka's One One, and you'll find breathless tributes to the support the shoes provide, their sturdiness and how surprisingly light they are, considering the sole is substantially thicker than that of standard shoes.
In numerous press releases Hoka celebrates the shoe's "unique ability to provide cushioning while still offering stability" and says "runners may greatly benefit from a product that is designed to greatly reduce the amount of stress on their lower legs and body."
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That's a lot of "greatly," but just as jazz is about the notes that aren't played, marketing vernacular can be best understood by examining the words that are missing.
Though stress reduction on the lower legs suggests a decrease in runners' injury risk, Hoka never flatly states that runners won't get hurt as often if they lace up the One Ones.
"There is no data at all to suggest one way or the other," he says. "But if this shoe is consistent with all other trends in footwear, we're not going to see a dramatic change in injury rate. Shoes don't seem to have that clear cut effect of reducing or preventing injuries as much as the manufacturers might suggest."
Maximalist shoes increase the amount of cushion in the shoe's sole without adding to the overall weight of the shoe by using low-density materials. They're popular – Hoka's 2014 sales were up 350 percent from the previous year – and, according to distance runner and Hoka spokesman Leo Manzano, an Olympic medalist in the 1,500 meters who holds the fifth-fastest event time in American history, are "like running on a cloud."
Maybe so, but Dr. Heiderscheit, also an orthopedics and rehabilitation professor in the University of Wisconsin School of Medicine and Public Health, will require a more rigorous review before offering his endorsement.
"We base our advice on as much science as possible," he says, "and there isn't a whole lot out there to back it up. We advise people based on what's comfortable for them. What feels right is a large factor in deciding what you should wear."
That's not to say shoe selection isn't important to distance runners. In his work at the Runners Clinic, Dr. Heiderscheit has traced the development of Achilles tendon and plantar fasciitis issues to a quick discard of more "structured" shoes in favor of flexible ones.
"When people change shoes and go from one style of shoe – not brand, but style – fairly rapidly, they can develop aches and pains," he says.
But common running problems like shin splints, stress fractures and knee and back soreness just as often can be traced to flawed running form or ill-conceived training habits.
"Seventy percent of all running injuries can be explained by training errors," Dr. Heiderscheit says. "People are putting on too much mileage, too quickly, and doing speed work before they're ready."
The Runners Clinic offers evaluations that not only critique a runner's training program but also include a complete history and physical examination that compares the runner's form to her body characteristics.
"Are you strong? Are you flexible? Are you well controlled?" Dr. Heiderscheit says in recounting the questions the Runners Clinic answers for each client. "We look at how you run and match your mechanics with your physical profile. Do those two go hand-in-hand or are you running in a way that is exceeding the ability of your body?"
More than choosing this shoe or that shoe, resolving biomechanical issues and harmful training habits will contribute to a healthy, successful running career.
"We want to make sure people understand the importance of running form," Dr. Heiderscheit says. "How the person runs plays a large role in injuries, and we can show people which running styles are more costly or less costly, and reduce their injury risks."