Feet actually change as we age, says Isphording. "As adults," she says, "we rarely have our foot measured because we just assume we know our size."
Determining your shoe size is essential for a comfortable fit. Keep in mind, too, that the size you wear in a Saucony shoe may not be the size you wear in an Adidas shoe.
Not only the size, but the shape of our feet change over time, she adds. If your foot flattens, for example, you may need to change the type of shoe you buy from one designed for stability to one with motion control.
Dress the Part
Don't go shopping for a new pair of running shoes wearing a suit, or flip-flops and no socks, says Isphording. "Wear what you would wear to run," she says, "especially wear the right sock. And if you have special shoe inserts or orthotics, bring those along, too."
Be careful about buying a shoe for looks, warns Wilk.
"The average time a consumer takes to pick out a pair of running shoes is about 10 to 15 seconds," says Wilk.
Knowing that, he says shoe manufacturers will use characteristics like looks, weight (lightness) and cushion to sell shoes because these are tactile factors that appeal to consumers.
"Fashion running sneakers," he says, "are hourglass-shaped because that shape makes the foot look smaller," Wilk explains. "No foot is hourglass-shaped. It's either C-shaped or straight.
"Cool-looking running shoes that work is really an oxymoron because a running shoe that works, at some point, looks like feet."
Don't Overdue It
Even if you find out you are a pronator with flat feet and weak ankles, you may not necessarily want to buy the stiffest, bulkiest -- what people in the industry call the "motion control" -- shoe, suggests Pittsley.
"The human body was made to move," he says. "If the shoe is too bulky, it almost causes the shoe to compensate for your weaknesses. A person should be able to control his own ankles and should be able to control the shock (the natural occurrence of the foot hitting the surface) a little," he says. "If you do it all with the shoe, it's like crutches to you."
In other words, he says, you may be doing yourself a disservice by getting an injury prevention running shoe before you actually need it: "Medium-weight trainers might satisfy many people."