What's the No. 1 quality to look for in a running shoe? Plain old comfort

Wondering about the best shoes to wear for summer running? Neutral? Minimalist? Stability? Motion control? Cushioned heel?

Confused?

Of course you are. But sports medicine specialists have good news: You can stop worrying about fallen arches, overpronation and putting your feet on a Paleolithic regimen. The latest thinking about how to choose the best running shoe is to let comfort be your guide.

Since the 1970s, running shoes have evolved from puny slabs of rubber sewn to canvas shells into engineering feats for the feet. And each new technological development has been accompanied by promises of running bliss.

"Historically, the push has always been to look at foot pronation," said Bryan Heiderscheit, a professor in the department of biomedical engineering at the University of Wisconsin-Madison.

Runners were told to wear shoes that would correct for the foot's tendency to roll inward or outward, on the theory that this would correct biomechanical flaws and prevent injuries to the knees and lower back.

"But the best studies that have been done in the last 10 years have not substantiated that claim," he said.

In 2010, the American Journal of Sports Medicine published a study of 1,400 Marine Corps recruits. Half the group was given shoes based on a careful evaluation of the shape of their feet. The control group's shoes were chosen randomly.

"Assigning shoes based on the shape of the plantar foot surface had little influence on injuries," the authors concluded.

When Heiderscheit tries to explain this to members of the running-shoe industry, he gets "pushback."

That's not surprising, he said, considering that the $20 billion athletic-shoe market sustains itself on innovation. Most companies release new models twice a year, offering features designed to improve performance and prevent injury.

The idea that almost any shoe is fine if it's comfortable also is apt to meet resistance from runners for whom theory has become dogma.

For instance, believers in barefoot running or minimalist shoes are unlikely to be convinced. Both types of shoes are fine, Heiderscheit said, as long as converts do not make the switch too abruptly.

Speaking from personal experience, he said that it's easy to get injured if you decide to toss your cushiony sneakers and immediately start racking up miles in a pair of barely-theres. It can take months to adapt. He recommends exercises to strengthen muscles in the calf and foot and using the minimalist shoes for short, easy runs at first.

"You should feel so comfortable in a shoe that you could sleep in them," said Jon Woo, a sports medicine specialist at the University of Washington in Seattle.

Experts say that just as everyone's feet are unique, so are their running styles.

"There is no absolute biomechanical ideal," Heiderscheit said.

One of the world's fastest marathoners, Pescah Jeptoo, has a knock-kneed gait that has carried her through 26.2 miles in a blazing two hours, 20 minutes and 14 seconds. For the record, she runs in Nike Zoom Streak 3s, a lightweight, breathable shoe with some support and cushioning. Online reviews of the shoe range from "I got huge blisters" to "Perfect!"

If this proves anything, experts said, it is that the one true authority on which shoes are best is the runner who wears them.