SAN ANTONIO -- Kathleen McBride has run for nearly four decades mostly injury free until this year.

"I was starting to have a couple of little nagging things bother me. In my hip and my feet bothering me a bit, said McBride, who will run the San Antonio Rock 'n' Roll 1/2 Marathon on Sunday.

So after doing some research on the Internet about barefoot running, she decided to ditch her shoes.

"The hip thing cleared up in the first week of barefoot running," McBride said.

There are theories and studies both for and against running barefoot.

Proponents say humans were born to run barefoot and point to the Tarahumara Indians in Mexico, who routinely go on 50-mile or longer runs in either simple sandals or nothing.

But not all barefoot fans do it because of science.

"Honestly, I just don't like to wear shoes," said Teresa Morris, who's run four marathons barefoot and plans to also run in the Rock 'n' Roll Marathon without shoes.

They all agree that running on the road doesn't cause any problems because just like with shoes, you avoid objects in your path.

"The primary rule of barefoot running is relax, relax, relax," McBride said.

"My speed actually increased," Morris said. "My times in my races, like 5Ks, increased."

Kathleen got in touch with Teresa and other barefoot fans online and they now get together a few times a week for group runs. It's about the only time they don't get the stares or hear the whispers.

"They'll be running behind you ... saying, 'Why is she doing that?'" McBride said.

"If you're going to start running barefoot, you have to be somebody who doesn't mind a lot of attention negative, or otherwise, because you are going to draw attention," Morris said.

And maybe pick up a few more converts along the way.