It was a string of knee injuries – a torn ligament, then an avulsion fracture, and a meniscus tear followed by surgery – that convinced Richard Ehrlich to try the glove-like Vibram FiveFingers ultra-minimalist running shoes, joining hundreds of thousands of others inspired by Christopher McDougall's bestselling 2009 book Born to Run.
"I had to relearn running to reduce the pounding on my knee," says Ehrlich, a 55-year-old dentist in Palgrave, Ont. "The FiveFingers helped teach me to run with a mid-foot strike, and to land over my foot and not behind it."
This less-is-more shoe philosophy helped Ehrlich return to running. But on long trail runs, he's as likely to run in a pair of Hoka One Ones, the newly ascendant "maximalist" shoes that boast oversized "extreme cushioning" – a seemingly contradictory but surprisingly common choice that illustrates just how complex and confusing the science of running shoes has become.
As the New Year rings in a fresh crop of fitness and workout resolutions, would-be runners are in danger of whiplash as they try to decode the shifting advice about what they should put on their feet. Back in 2012, U.S. sales of barefoot-mimicking minimalist shoes soared to a peak of $400-million, buoyed by claims they promoted a more natural running stride that would eliminate injuries. But sales have tailed off, and last year Vibram agreed to pay $3.75-million to more than 150,000 FiveFingers customers to settle a class-action suit regarding its injury-prevention claims. Meanwhile, ultra-cushioned shoes like Hokas have surged in popularity.
So which is the right shoe for you? Well, it's complicated.
"I think in 2009 people were pushing minimalism as the cure-all to running injuries, whereas now we have research showing that injury rates are pretty much the same in traditional and minimal shoes," says Peter Larson, a biologist and running scientist in New Hampshire who left a tenured academic position in 2013 to focus on his shoe review site, Runblogger.com.
That doesn't mean there isn't a different injury potential between minimalist and conventional shoes, Larson points out. When the minimalist trend took off, shoe researchers launched dozens of studies that now are appearing in academic journals. The results paint a more nuanced picture than the sales figures. For example, biomechanical studies show that different shoes distribute stress to different parts of the body: feet and ankles from minimalist shoes, knees and hips from more-cushioned conventional shoes.
"The challenge now is finding the right shoe for the individual and their particular injury susceptibility," Larson says.
Varying running conditions may also call for different shoes. Hoka's mega-shoes, which boast twice the cushioning without adding weight, first caught on among ultra-marathoners and mountain runners when they were introduced in North America in 2010. The extra cushioning seemed to help deal with rough terrain, especially as fatigue set in late in long races.
That's what sold Brian Martin, a 36-year-old ultrarunner and doctoral candidate at McMaster University's Department of Kinesiology. He had spent nine months transitioning from conventional runners to FiveFingers, and loved the agility and strength he developed in his feet. But when he wore them for a 100-mile race along highly technical trails, he developed a bad case of plantar fasciitis. To recover, he began running in Hokas.
"Although I loved the Vibrams," he says, "with the Hokas, there's no thinking about foot strike. You just run, and run over everything." He now intends to alternate between minimalist shoes to strengthen his feet, and maximalist shoes to protect them.
Ehrlich, too, sees a role for both shoes. His coach, veteran ultra-runner Derrick Spafford, convinced him to try Hokas for 100-kilometre trail races. The first thing Ehrlich noticed was how easy it felt to run downhill. "I went from being a weak downhiller to being known as a downhill flyer," he says. He still uses a variety of minimalist shoes, but not for the longest distances. "At this point," Ehrlich says, "I will never run another long ultra in anything but a Hoka or similar cushioned shoe."
The Hoka trend has spread from ultrarunners to the mainstream (the company was snapped up in 2013 by Deckers Outdoor Corp., which owns brands such as Teva and UGG Australia). But is there any evidence that super-cushioned shoes have benefits for average runners?
Blaise Dubois is skeptical. The Quebec City-based physiotherapist, who lectures on running injuries, sees the potential benefits of Hokas as limited to those with unchangeable conditions in their feet such as Morton's neuroma or osteoarthritis. Similarly, he sees no reason to recommend conventional running shoes except to those who are currently running happily and healthily in them, and those with specific foot and ankle problems – and for the latter, mostly as a temporary measure. Several recent studies failed to find any benefit in conventional "motion-control" shoes, prescribed based on how much your foot pronates, Dubois points out. As a result, he argues the default option, particularly for children and new runners, should be relatively minimalist shoes that promote a more natural running gait.
Still, while Dubois has been recommending minimalist shoes to his patients for more than a decade, the recent flurry of research has convinced he and his colleagues to make two key changes in their clinical recommendations.
The first is the time frame for transitioning to new shoes. A minimalist stride may be "natural" for Kenyan runners who grew up barefoot, but people who have grown up wearing stiff, protective shoes require up to nine months to build the necessary foot and ankle strength. Rush the transition, and you're vulnerable to injuries such as stress fractures in the foot and Achilles tendon problems.
The second change is a realization that not everyone needs to go right to the shoe extremes. Along with his colleagues Jean-Francois Esculier and Jean-Sébastien Roy, Dubois has been developing a "minimalist index" that uses such factors as flexibility, weight, heel-to-toe drop and sole thickness to quantify exactly how close a shoe comes to simulating bare feet.
With these differences in mind, Dubois would steer a beginner with a history of injury in the foot or lower leg to a light training shoe that scores 40 to 50 per cent on the index, while someone with a history of injury to the knee or hip would be guided to a shoe that scores higher on the index.
These nuances make choosing the right shoe even more difficult. The old way of prescribing shoes has been debunked; the new way didn't fulfill the hype either. But almost everyone agrees that we're better off in one important respect: We have more numerous and varied choices.
The flowchart devised by Blaise Dubois and his colleagues at The Running Clinic looks more like the blueprint for a nuclear reactor than advice for buying shoes. It takes into account experience, injury status, running style and goals to suggest a shoe type and a timeline for adapting to new shoes. It's complicated – but so are humans.
Alex Hutchinson blogs about exercise research at sweatscience.runnersworld.com. His latest book is Which Comes First, Cardio or Weights?