This story first appeared on Triathlete.

If you’re in the market for a pair of insoles, don’t just turn to your training partner for a recommendation. A growing body of literature has highlighted how highly individual the prescription process can be. It turns out, when it comes to selecting insoles, your own intuition may be your best resource.

Research by famed biomechanist Benno Nigg suggests that our bodies follow a “preferred movement path,” which is unique to each individual. The thinking goes that when you alter that movement path, the surrounding muscles are forced to activate and work harder. In terms of insoles, either a heavily structured orthotic that prevents natural pronation or a flimsy insert that doesn’t provide any support can both potentially interrupt this process, depending on the individual.

Nigg tested this theory on a class of military recruits, offering them six different insole options with varying degrees of support and cushioning. At the end of basic training, they discovered that the recruits who selected an insole solely based on what they perceived to be most comfortable had a lower likelihood of developing an injury. It is hypothesized that when we rely on comfort, we are falling back on our own intuition to choose the option that best supports natural movement patterns.

“Comfort is the most important aspect of fitting not only insoles, but also shoes,” says Dr. Paul Langer, DPM, a podiatrist and the president of the American Academy of Podiatric Sports Medicine. “I educate my patients on how comfort can give clues about how the footwear—shoe, insole or orthotic—works with their movement pattern and that they should always select what feels comfortable, natural and least cumbersome.”

As for whether you need an insole in the first place, that depends on injury history and personal preference. Langer often prescribes them for general foot pain, patellofemoral pain and plantar fasciitis, among other issues.

“I always emphasize to my patients that an insole is a tool to be used as often or as little as needed based on their preferences,” he explains. “There seems to be a fear that if you start to use one, then you become dependent on it, which is certainly not true.”

The bottom line is if you suspect you may benefit from an insole—and have ideally had a doctor suggest you try them—let comfort be your guide in the selection process. For athletes with injuries and chronic ailments, consult your podiatrist to get a read on whether you should first try an over-the-counter option before taking molds for a custom-made variety. Regardless of what you put in your shoe, remember that if it doesn’t feel right, it probably isn’t.

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