Injury Prevention

Biomechanics Experts Share Running-Injury Research and Advice

Irene Davis and Daniel Lieberman explain their views on how to reduce running injuries.

Veteran running injury researcher Irene Davis believes the key to healthy running is to run soft with good alignment. Evolutionary biologist Dan Lieberman says we should walk, run slow (with occasional sprints), dance all night long, and sit on our haunches or on rocks around the campfire.

Saturday morning, January 30, Davis and Lieberman summarized their views in 40-minute talks presented over Zoom in a symposium organized by World Athletics and the International Institute for Road Race Medicine (IIRM). After, they spent another 40 minutes answering questions from an audience composed largely of marathon medical directors from Boston, Houston, Madrid, and other major events.

Davis is a professor of physical medicine and rehabilitation at the Harvard Medical School as well as director of the National Running Center in Cambridge, Mass. She has been involved in various aspects of running-injury research for 40 years. In recent years, she has focused on the differences between forefoot and rearfoot running biomechanics, and on efforts to teach runners to adjust their running form. This was once believed almost impossible like changing your fingerprint. Davis has shown both that it can be done, and that it can help runners reduce pain and injuries.

Lieberman first hit the national running headlines in 2004 when he and colleague Dennis Bramble published an article that the editors of Nature magazine titled “Born to Run.” The phrasing struck, especially when it also appeared on the cover of Christopher McDougall’s best-selling book. Lieberman seemed at first mainly interested in barefoot-minimalist running, but has since expanded his perspective to evolutionary health, particularly the “mismatch” between the current environment and conditions one to two million years ago.

It turns out he’s not a cultist, but the opposite. He’s forever explaining how homo sapiens evolved with different approaches in different regions of Earth. There’s not one true and rigid path. His new book, Exercised, explores how our current fixation with exercise is WEIRD that is, limited to countries that are Westernized, Educated, Industrialized, Rich, and Democratic. We shouldn’t make broad generalizations, because “that’s only 9 percent of the world’s population,” he notes.

Put Running Injuries In Perspective

Lieberman believes that the risk of running injuries has been exaggerated, or at least taken out of context. There’s no universal definition for a running injury, he points out, and most probably occur among those who are just beginning to run and those who are pushing their limits. “Nobody would be running if injuries were as bad or as common as we hear,” he says. “Most of us in the middle between beginners and 100-miles-a-week aren’t doing badly.”

Besides, there are tradeoffs involved in all our activities. When some chimpanzees came out of the trees and evolved into bipedal runners, they ended up on “two tippy legs.” It shouldn’t be a surprise that this would lead to instability and injuries. The chimps who remained in trees also got injured. “Sixty-five percent of them got hurt falling from the trees,” Lieberman asserts. Every human activity involves risks and benefits.

He also advises that we don’t succumb to “paleofantasies.” Not everything that is natural and/or ancestral is good, not everything modern is bad. Running shoes are a great invention when it’s snowy and below-freezing in Cambridge, Mass., where Lieberman lives and runs through the winters (so are treadmills). “We shouldn’t be asking if shoes are good or bad,” he states. “That’s a silly question.” The sharper question is whether or not they serve us in certain conditions and environments.

Headshot of white man.
Evolutionary biologist Daniel Lieberman. Photo: Wikicommons

Hip Strength Alone Doesn’t Prevent Injuries

Davis spent a fair amount of her time discussing injuries apparently related to the hip adductors. Many studies have shown that bad things happen when the adductors allow the knee and lower leg to torque inwards too far. Physical therapists and others have logically deduced that strengthening the hip adductors should reduce these issues, and research has likewise shown that it is possible to achieve such an effect.

But there is one problem, according to Davis: Adductor strengthening doesn’t actually reduce injuries as hypothesized. That’s why she mounted a mirror in front of runners on a treadmill, and advised them to run softly and without excessive inward leg roll. As they got better at this, she gradually began removing the mirror a system she calls “faded feedback.”

After eight sessions, the runners were experiencing significantly less pain in and around the knee. “I liken strength to computer hardware,” she says. “You need it, but you also need the right software, which is the correct movement pattern.”

Focus on Form

“Did we evolve to run?” Lieberman asks. “The answer is, ‘Absolutely.’ But we didn’t necessarily evolve to race marathons or even to follow formal training programs.”

When he’s doing field work in Kenya and heads out for a morning run, the locals laugh at him. “In Kenya, the kids run when they are late for school, and adults only run if they think they can make money from it,” he observes. In Mexico’s Copper Canyon, home to the famous ultraruninng Tarahumara, there’s no word for “training.”

Lieberman believes that many Westerners adopt an individualistic, run-naturally approach to their running. They believe in running free that is, without much thought to how they are moving. In Kenya, by contrast, the athletes mimic each other with follow-the-leader running drills.

“I don’t think there’s anyone who doesn’t agree on several key running form patterns,” Lieberman says. These include: 1) Don’t overstride by placing the foot on the ground in front of the knee; 2) Don’t lean forward too much, particularly not from the waist; and 3) Don’t run with high, tight shoulders. Lastly: “We should make our running more recreational and more fun.”

College girl runs on treadmill while researchers examine her running form.
Dr. Irene Davis at the Spaulding National Running Center. Note: This photos was taken pre-Covid-19 and does not reflect the protective measures currently being taken at the center. Photo: courtesy of the Spaulding National Running Center

Be Leery of Shoes with Excessive Flare and/or Midsole Thickness

Davis is no fan of overbuilt shoes. In particular, she finds that shoes with a large heel flare or thick cushioning tend to increase lower leg movements to an extent that they lead to injuries. (Heel flare refers to an outward angling midsole that results in the outsole of the shoe being wider than the actual heel width.)

Her studies and others have shown decreases in knee pain among runners who switch to minimalist shoes. Davis advocates running in shoes with zero drop to 2mm, adding cushioning only if you need it. Yes, calf and Achilles issues can become a problem. The transition must be gradual, and you must strengthen the calf muscles and the foot muscles.

She doesn’t suggest a shoe change for anyone who’s running strong and injury-free in their current shoes. However, she does quote one study of novice runners who were trained to run “softer” (largely with a forefoot strike) and then suffered a 62 percent lower risk of injury in the next 12 months vs those who received no such training.

How can someone transition to forefoot running and more minimalist shoes?

Lieberman: “Very carefully. Very gradually. Remember that there’s a tradeoff in forces. Forefoot running will put more strain on the calf muscles and Achilles. You need to develop more foot strength. People transition too fast. They should realize that it takes the musculoskeletal system weeks and weeks to adapt to new forces.”

Davis: “Start by just walking in minimalist shoes before you use them for running. Build up the calf muscles. Do double-leg heel raises, then single-leg raises, then single-leg hops. Use a run-walk system that gradually decreases the amount of walking you do while increasing the runs. Pay attention to pain. Take days off when you need them. Age always matters. As we get older, we become less plastic.”

Are the new super shoes likely to cause injuries?

Lieberman: “We actually began to study that last winter, but then came Covid. We heard reports of runners who felt a yanking in their calf muscles from the built-up shoes. You have to realize that not everyone is Eliud Kipchoge. He has such strong calf muscles that he can run 26 miles in thick shoes and maintain a barefoot-like running form. Not many can do that. We should remind ourselves that elite runners are not relevant to most average runners.”

Davis: “We don’t know about the injury question yet. The guys running super marathons in super shoes are really strong and fit. I would never tell one of them not use the new shoes. But recreational runners are totally different from two-hour marathoners.”

What’s your wrap-up message?

Davis: “We need to move more. Movement is part of what gave us a more developed brain. You can run, or you can engage in any other form of movement. We should also free our feet more. Spend some time barefoot. Open your toes, spread them wide. Let your foot muscles have more chance to do what they were evolved to do.”

Lieberman: “We live in a challenging time. The pandemic has made it difficult to stay connected, and to keep exercising. I know my step counts are down. We should remember that running is one of our most basic physical activities one that keeps us mentally and physically healthy. We’ve seen too much evidence of increasing inequalities of access to healthcare and physical activity. We’d all be in a better place if we’d get out there more, have some fun, get our heart rate up. We should focus on the joy of movement more than anything else.”