Too Much of a Good Thing?

Story and Photos by Ian Vorster

Out on the Trail

Anecdotal evidence carries a hefty kick in athletic circles. If a long-distance runner tries on a new pair of shoes and says that after 4 or 5 miles she notices significantly less muscle fatigue than before, her running buddy might be inclined to try a pair. But with super-cushioned running shoes, also known as maximal shoes and first produced by running shoe company HOKA ONE ONE, it’s more a case of oil and water — some love them, others hate them.

Sherri Dean hates them. The OSU-Cascades undergraduate research assistant and recreational runner has completed many 5K and 10K races since relocating to Bend, including last year’s Silver Falls Trail Half Marathon. Dean enters the races to remain motivated and to partake in the social side of the sport, and she enjoys the trails with her dogs and her children if she can get them to join her.

“I did try maximal shoes once, but they didn’t suit my running style,” she says. “I just did not enjoy them. Within a mile, I had knee pain. Never had it before, never had it since. But that’s just me.”

Erin Kevin loves them. She started running last year and describes herself as overweight and fast approaching middle age. She was inspired by Mirna Valerio, author of the Fat Girl Running blog and the book A Beautiful Work in Progress, because Valerio promotes running as an accessible sport for all body types.

“I used to be an active hiker, but I wanted the scenery to go by a little faster,” she chuckles. “And my dog has a lot of energy so together we started running.”

Kevin has run a 5K and a 10K and is now training for a half-marathon. She was introduced to maximal shoes in February after turning her ankle on a rock on the Deschutes River Trail, producing severe foot pain.

“I wanted a stable shoe with more cushioning and started running in a pair of HOKAs in March,” she says. “I completed the first mile with some difficulty and then the next three without any discomfort at all.” That was Kevin’s first post-injury run, and she now regularly runs up to 6 miles in her maximal shoes without pain.

Back in the Lab

Sporting a broad smile in a lab at Oregon State University-Cascades in Bend, Dean stands with her feet placed squarely beneath her shoulders and her arms arched above her head. Christine Pollard and JJ Hannigan are attaching marble-sized reflective balls to Dean’s shoes and at points on her knees, thighs and waist. Pollard is the director of the Functional Orthopedic Research Center of Excellence (FORCE) Laboratory, and Hannigan is a postdoctoral researcher.

Eight high-speed infrared cameras located on scaffolding just beneath the ceiling will project light, capture the reflections from these small spheres and transmit them to software on a nearby computer. The software will then overlay the reflective points on the skeletal system of a runner. As Dean is running along the test lane, she will step on a platform that measures the impact generated by her footfall.

Why is Pollard so interested in this? “I started out as a physical therapist so my goal is to better understand lower extremity movement to reduce injury,” she says.

Both Pollard and Hannigan are interested in exploring some of the conflicting anecdotes made by maximal shoe users. The FORCE Lab provides cutting-edge research and correction strategies for injuries, especially as related to knees, ankles and hips. Since the lab supports Central Oregon’s population of elite and recreational athletes, it is interested in squaring those anecdotal reports with research findings.

Hannigan, who as a competitive track and cross-country athlete struggled with injuries, echoes Pollard’s sentiments and adds, “We’ve heard many subjective reports from runners who previously experienced knee pain several miles into their run and are now pain-free after switching to HOKA shoes. But we’ve also heard the opposite.”

Recent History

Traditionally running shoes have had a moderate amount of cushioning, with the various brands being differentiated by how much control they provided for pronation — or inward rotation — of the feet. The heel of the majority of these shoes was at least a half inch higher than the toes — known as heel-toe drop.

“Between the ’80s and about 2009, most footwear companies produced a range of running shoes that had one thing in common — all had a reasonable amount of heel-toe drop,” Pollard says. “At one end of the spectrum, they had more stability, and at the other end they were more cushioned. But all had more cushioning under the heel than they did under the forefoot.”

In 2009, the industry produced two innovations — minimal running shoes and maximal running shoes. Both styles had far less heel-toe drop, but the minimal shoes had less than a quarter inch of cushioning while the maximal shoes had almost an inch.

Help or Hindrance?

In this context, the science of biomechanics focuses on the effects of forces on the body when subjected to different athletic and recreational activities. More importantly for runners, it includes the study of injury prevention. Researchers focus on the relationship between force, the body and motion. The principle concerns for protecting runners against injury are the need for cushioning, rear-foot control of pronation and forefoot stability. To study these concerns, biomechanists use a device known as a force-platform along with high-speed video capture and other types of measurements.

Using force-platform analysis — a test that involves a runner stepping on a platform to measure the force exerted — scientists are able to identify the most prominent footfall pattern where the heel strikes the ground before the toe. Researchers found that there is an initial peak, referred to as the impact or passive peak, and a second peak, known as the push-off or active peak.

The body has to mitigate the shock through the bones and cartilage or by changing its geometry — in other words by compensating. It was, of course, believed that footwear should help cushion the foot-ground collision, but surprisingly it was found that a softer midsole offered no benefit over a hard midsole.

Which is why Pollard and Hannigan thought they would see these reductions in the HOKA shoes. “But we didn’t, we saw the opposite,” says Pollard. It may be that runners are relying too heavily on the maximal soles and are not using their internal musculoskeletal structures to dampen the forces adequately.

“And we didn’t see any change in the loading rate or impact peak after six weeks of acclimating to the HOKA shoe either,” says Hannigan. The average loading rate and impact peak were still significantly higher in the HOKA shoe compared to the traditional shoe.

In other words, the FORCE Lab has now twice found that maximal shoes actually provide less functional cushioning than the old traditional, tried and tested training treads. Could too much of a good thing be bad for runners? If runners love their HOKAs, then the answer might be a resounding no, but if they hate them, the FORCE Lab’s next study might show why.