When it comes to running shoes, size matters. Buying shoes on size alone won't always get you the best fit, though. As you run, the impact causes your foot to splay and your toes to push forward.
Running shoes that are too tight lead to blisters and toe pain, while shoes that are too loose cause your foot to slip around leading to ankle or knee injuries. Understanding where your shoe needs to have room and where it should be snug will help you get the best fit for your run, according to the American Academy of Orthopaedic Surgeons. If you can, buy your shoes at a specialty store.
Your running shoes should have extra space at your toes, fit you like a glove around the middle of your feet and be snug at your heels.
Roomy at the Toe
During a run, the extra blood and fluid flow and the impact of each strike causes your foot to swell. To accommodate for this, your running shoes should have extra space at the toe and the toe box, says the American Heart Association. When standing in your shoes, there should be a thumb's width of space between the end of your longest toe and the tip of the shoe. You should be able to wiggle your toes.
Glove-Like at Mid-Sole
To provide stability and support while still being comfortable, the middle portion of your running shoe should fit like a glove. The fit should be comfortably snug without having to overly tighten the laces. If you find a shoe that fits well but feels a bit too loose or too tight at mid-sole, different lacing styles can help change how the shoe conforms to the middle of your foot.
Snug at the Heel
A shoe that is too loose or too tight at the heel will leave you with blisters after even a short run. When trying on shoes, lace them up and walk around. If you feel the shoe slipping around at the back of your foot, the shoe is too large. The heel should also not feel tight or constrictive with the shoe laced up. There should be an overall snug feeling at the back of your foot, says the American Orthopaedic Foot & Ankle Society (AOFAS).
Great Fit All Over
A pair of running shoes should feel comfortable the moment you slip them on. If you buy shoes with the thought of breaking them in, those shoes don't have the best fit for your foot. When shopping for running shoes, wear the type of socks you normally wear on a run, and go in the late afternoon.
This is when your foot is somewhat swollen, says the AOFAS, so you'll get a better indication of how the shoe will fit during a run. In many cases, running shoes need to be half a size larger than other shoes so be willing to try on a shoe that is slightly larger than you normally wear. Above all, try out your shoes by running on the surface you run of most often.