Found on RunnersWorld.com and written by Jonathan Beverly
One biomechanist suggests that whatever feels right, is right.
Don’t worry about pronation control, stability, or even cushioning when choosing shoes—wear what feels good and you’ll be more efficient and have fewer injuries. That’s the bottom line of a recent discussion paper published in the British Journal of Sports Medicine that sparked a flurry of web stories, such as this New York Times piece.
The BJSM paper reviews studies on footwear and injury over several decades, revealing that there is little scientific evidence connecting pronation and running injuries, nor evidence that cushioning prevents injuries—two factors often used to choose running shoes. It goes on to propose that instead of correcting your stride, shoes should support each runner’s “preferred movement path” and the best way to assess that correlation with your personal stride pattern is the subjective filter of “comfort.”
Is it really as simple as “If it feels right, wear it?” Answering that requires looking at the concept of comfort and how well we can access it.
The ideas in the BJSM paper were first suggested in 2001 by Dr. Benno Nigg, lead author of the study and emeritus professor of kinesiology at the University of Calgary in Canada. He expanded the themes in his 2010 book, Biomechanics of Sports Shoes. This new review adds some evidence, particularly referencing a large 2014 study that shows mild pronators are the least injured runners, but the conclusions remain the same. Nigg’s hypothesis states that when runners select shoes or inserts they deem the most comfortable, they run more efficiently and have fewer injuries. From this, he proposes that the “comfort filter” is the best method for selecting shoes.
The Limits of Comfort
While other biomechanical experts concur with the lack of strong evidence for many of the ways shoes are categorized and marketed, they express reservations that comfort solves all problems. Biomechanics expert Martyn Shorten, who heads the Runner’s World Shoe Lab, applauds Nigg’s summary of how the old paradigms are not working and his suggestions of new ones, but Shorten points out that Nigg’s hypotheses have yet to be independently studied in controlled experiments. As Nigg clearly states in his papers, they are still suggestions that require much more research and validation to be accepted as overarching truths. Shorten also has concerns with the fact that comfort is a psychological outcome, not a characteristic of a shoe, and as such it makes it difficult to measure accurately.
“The sensation of comfort is imperfect and not very repeatable,” Shorten says. “On a given day, it is biased by each subject’s experience, their mood, the environment, and many other factors.”
Geoff Gray, president of the Heeluxe shoe research lab in southern California, says, “Comfort is part of the equation, but it can’t do everything.”
Gray expresses reservations about whether all runners have the ability to assess all the elements that make a shoe work for the running they are doing. “It depends on the population,” Gray says. “Competitive cross country runners who have a well-defined movement path might be very savvy about what shoes work for them, but for a group of beginners in a marathon training program, comfort might be only what they are used to or what fits best—and might not be the best running shoe for them in that setting.”
Jay Dicharry, director of the REP Biomechanics Lab in Bend, Oregon, and author of Anatomy for Runners, also agrees with Nigg’s ideas on preferred movement paths. His concerns center on whether runners can use comfort in a convenient way to select shoes. “A lot of runners don’t try enough different shoes,” Dicharry says. “They’ve been in the same shoe for a long time, and they’re not willing to try something slightly different, let alone radically different.”
Dicharry also fears that an emphasis on comfort, as generally understood, encourages the perception that more is always better, and that a squishy marshmallow foam that feels good while walking around a store will be deemed appropriate for one’s tempo runs.
What Is Comfort?
Nigg is quick to acknowledge limits to his conclusion. Even in the new paper, he and his colleagues admit, “Comfort is difficult to define and to quantify.” And understanding his “comfort filter” is key to utilizing it. Unlike the way we use the word in daily conversation, Nigg’s “comfort” represents more than fit, softness, or cushioning.
“Comfort is a more overarching term,” says Sandro Nigg, Benno’s son and owner of Biomechanigg Sport and Health Research. The Niggs tie the idea of comfort with the preferred movement path. Your body wants to move in a certain pattern unique to your bones and joints, and will naturally follow this path. This is why you can pick out your running buddy from an approaching crowd of runners a half mile a way.
While different shoes won’t affect this pattern much, Sandro Nigg explains, some will require you to use more muscles to achieve your preferred stride pattern. In effect, you are fighting the shoe in order to run the way your body prefers. The best shoes for you will let you run as you are built to run with the least muscular effort.
Preferred Path and Support
Note that neither the concept of “preferred movement path” nor the “comfort filter” eliminate shoes that offer control. Through their own research at the German Sports University in Cologne, Brooks Running has developed a similar concept that is informing their shoe design and marketing. Brooks wants to build shoes that allow each runner to follow their own “stride signature.” That’s not the same, however, as saying all shoes should be similar to going barefoot.
Carson Caprara, Brooks’ senior global product line manager, explains that while the body has a way it wants to run in a vacuum, external forces such as gravity, inflexibility, or muscle weaknesses can make it hard to maintain that pathway. If you lose the ability to maintain your natural pattern, your body accepts help from the shoe. “The support of the shoe, instead of stopping motion, is supporting the preferred motion,” Caprara explains.
For Nigg, the comfort filter will, ideally, identify this. If you need a support post in your shoe—because your foot doesn’t want to pronate but is pronating because of fatigue—a shoe with a post will feel most comfortable on the run. But assessing this requires a lot of self knowledge and often doesn’t become clear until you’re in the middle of a long run at the end of a long week. Or it can change day to day depending on your speed, your fatigue, the time of day, or even your biorhythmic cycles.
Even the Niggs admit to difficulties in our ability to accurately assess comfort. Sandro points to a 2002 study conducted by their group that showed that two-thirds of the subjects struggled to provide a consistent assessment of the comfort of shoe inserts on a sliding scale from day to day. They were more consistent with a simple “Yes/No” response to “is this insert comfortable” but still had less than 50 percent consistency.
Help From an Expert
Given the limits and difficulties of the comfort concept, is there still room for advice from the shoe fitter you can find at a specialty running store? Every expert consulted (even Sandro Nigg) agrees that a knowledgeable shoe fitter can help you know if you need support and guide you to shoes that will end up being the best—and the most comfortable for you. The caveat is that not everyone giving advice is knowledgeable.
Brooks is working on a system that will measure your preferred path in a controlled setting, then see how far you deviate from that when you are running. That system is rolling out to specialty shoe stores during 2016.
Apart from such a methodology, one way to assess if a fitter knows his or her stuff is whether they look at the whole picture. A good fitter will ask you about the volume and type of running you do, your training history, and any pain or injuries. They will also look at your foot shape, measure range of motion, and acknowledge different stride elements—not focus simply on a single element like pronation.
When it comes to the shoes, an expert will also understand how the whole shoe works together. “How we ID a stable shoe is not necessarily what we think,” says Gray. “The Kinvara 3, for example, was a really stable shoe because it had a wide base and was low to the ground, even though it didn’t have support devices. You need to look at the entire shoe.”
With or without the advice of a shoe fitter, research suggests that you may want to trust your instincts more on what shoe feels right on your body. But finding comfort requires more than stepping in and lacing up. You can’t judge comfort sitting in a chair. “Go for a run—you want to push it a little bit,” Sandro Nigg says.
Dicharry agrees: “If you’re going to use the shoe for fast running, run fast in it. When speed changes, your stride changes, and how the shoe behaves changes.”
Make sure you try on multiple shoes. It is easier to compare comfort between shoes than to assign a value to one. “You may try on one pair and think, ‘These are pretty good,’” Nigg says. “But then you try on another and find they are better.” Don’t get locked into a certain category or brand: try shoes from a wide spectrum. At the very least, there may be a lower threshold of comfort, Nigg suggests. “You can tell when something is uncomfortable, and you can stay away from those ‘bad’ shoes for you.”
Time also affects your comfort assessment, Nigg points out. “You might buy a shoe and it feels good for the first or second run, but a week later you know that something isn’t right.” Pay attention to that feeling; it probably means the shoe is interfering with your stride. “It’s okay to make a mistake,” Nigg says. “Sometimes you may need to do something twice.”
In the end, what Nigg’s hypothesis suggests is that shoes that work for you are the right shoes for you regardless of any expert advice on what shoe category you “should” be in. Many experienced runners would agree that they know best what they need, which is one reason why our redesigned shoe guide in the September issue of Runner’s World starts with the question “Do you know the type of shoe that works well for your size, stride and preferred ride?”
If you don’t, we can help you narrow your choices. (You can’t, after all, put 100 test miles on every model made.) We do this by directing you to products that we expect to work for runners with your body type and running habits. In the end, your task as a runner is to find what works, what is most comfortable on the run, for the unique individual you are.