It’s a sad time for minimalist runners. First Vibram agreed that it would pay out $3.75 million to runners who bought its FiveFingers shoes.

This is the glove-like footwear that allows you to wriggle your toes, and feel almost as natural as going barefoot.

Then last week the whole minimal/barefoot running movement suffered a setback when the U.S. Army presented a big study casting more doubt on the benefits of running this way.

If you’ve got a pair of FiveFingers, you can now return them for $20-$94, and go back the thick-heeled running shoes that have dominated sports store shelves since the 1970s.

Or you can send them to me (size 81/2). I am a true believer.

Vibram got into its legal trouble for suggesting the FiveFingers might reduce the risk of injury.

The argument goes that running barefoot, or nearly barefoot, forces you to change your gait. With thick-heeled shoes, you pretty much have to hit the ground with the heels first. All that rubber protects your heel from the pain of that impact.

But if you strike first with the front or middle of your foot, your ankle tenses like the coil of a spring, reducing some of the shock. That protects every other joint in your body, especially your knee.

Some smaller previous studies, including one of runners on the Harvard University cross country team supported that idea.

And it has been exactly my experience. I had pretty much given up running until I got my FiveFingers because my left knee was hurting so much. Now I’m tearing up the trails again.

The Army Runners

But the new Army study suggests that lots of people — or at least the average soldier — won’t prevent injuries by avoiding heel strikes.

“There appears to be no difference in the prevalence of injury in heel-strike runners vs. non-heel strike runners,” the lead researcher, Maj. Bradley Warr of the U.S. Army Research Institute of Environmental medicine, told me.

We met in Orlando, Florida for the American College of Sports Medicine annual meeting. He had dressed in his red-white-and-blue uniform and was about to deliver the news to an audience of physiologists who have held long debates on this topic.

As Warr talked, I pictured guys in camo and lace-up boots jogging in formation. That’s not how it happens, Warr told me.

These days soldiers wear government-issued shirts and shorts, but they can pick their shoes for training, as long as they have closed toes. (No FiveFingers allowed, but shoes with thin soles and no padding in the heel are OK.)

For the study, Warr and his colleagues made video tapes of 1,027 soldiers running, then analyzed the tape to see how each soldier’s feet hit the ground. Then they looked in the soldiers’ medical records to see whether they had running-related injuries.

They found that 15% of the non-heel strikers and 18% of the heel strikers had reported injuries, but the difference was not statistically significant.

The study is sure to carry weight among experts because it’s the biggest one to look at the question of heel-strikes versus non-heel strikes. And it’s enough to convince Warr that the Army shouldn’t try to get all soldiers to stop striking with their heels. “If it’s not broke, don’t fix it,” he said.

But I still think there are reasons that everyone might want to try running barefoot or in Vibrams, and I explain why (and how) in my next post.

For more details on the Army study, see my report for Medscape Medical News.