(AP) - Last month, after returning from an eight-mile run, Tsuyoshi Yoshino heated up a three-inch sewing needle until it turned bright red. Then, he says, he plunged the glowing instrument into the ball of his foot, puncturing a three-inch-long blister.
Despite the risk of infection, he walked around his San Diego house for 20 minutes on the open wound to get used to the pain. "It's not something I like doing," he says. "But I have to."
While other marathoners train by carbo-loading, Mr. Yoshino has a more painful regimen. The 32-year-old graduate student at San Diego State University is one of a growing cadre of formerly shod distance runners making a torturous transition to running barefoot in the hope of improving their times and strengthening their soles. Blisters are an inevitable part of the journey. Mr. Yoshino estimates he's popped about 40 of them in the past 18 months.
Over the years, a handful of world-class runners have been able to compete barefoot because they had run that way all their lives, hardening their feet naturally from early childhood. Among them: Ethiopia's Abebe Bikila, in the 1960s, and South Africa's Zola Budd Pieterse two decades later. But for runners long-accustomed to cushiony footwear, making the switchover often involves bizarre, agonizing feats.
"I wish there was an 'Idiot's Guide to Barefoot Running,'" says Mr. Yoshino, a former collegiate cross-country athlete. In 2002, he completed the Boston Marathon, in sneakers, in two hours and 43 minutes, placing him among the top 260 finishers.
Nowadays he limps to a halt after eight miles because his bare feet heat up and blister. Since commencing barefoot training through the streets and hills of San Diego 18 months ago, he's consulted an acupuncturist for pain relief. A sports-injury specialist taught him to remove deeply embedded thorns from his feet with a box cutter.
Mr. Yoshino says he'll need to lance another 100 blisters before achieving his dream, an outer crust on his feet as hard as that of some Australian aborigines. "It's no picnic," he says.
Although no one knows how many competitive and recreational runners go barefoot, membership in Yahoo's barefoot discussion group has tripled to about 1,100 since 2003. Track teams at several colleges and high schools, including the state universities of Texas, Arkansas and Oregon as well as South Lake High School in Groveland, Fla., have incorporated barefoot runs into their training circuits.
Because it demands discipline and a high tolerance for pain, "I like to call barefoot running 'Accidental Zen,'" says Ken Bob Saxton, a 51-year-old marathoner and computer technician from Southern California. Known as "Barefoot Bob," he practices what he calls "toe yoga" for sole strengthening, placing his feet flat on the ground and using his toe muscles to point his toes straight up until the feet start to hurt. Mr. Saxton says he was one of eight barefoot runners to finish the Los Angeles marathon in 2005; in 2000, he was the only one.
Paul Keeley, a U.S. Marine at the South Carolina Military School, wants to run the Boston Marathon unshod next year. Last summer, he began training by pounding the streets of Charleston, S.C., in combat boots, hoping to nurture some preliminary calluses. He took off the boots this fall but soon landed on a surgeon's table for an abscess in his middle toe that required draining. Mr. Keeley, 18, says his calluses had hardened so well that he felt no pain when a pine needle or some other sharp object penetrated his skin and worked its way to the bone. He says he's still on track with his barefoot-in-Boston plan.
"Barefoot running isn't for sissies," says Jonathan Summers, a 37-year-old Boston horticulturist who took up the regimen this summer after seeing a couple of unshod runners pass him by at a local 10K race. "It's like running on sandpaper."
When his blisters hurt most, Mr. Summers dons a running shoe with ballet-slipper like soles to mimic the barefoot experience. Footwear maker Vibram USA sold 10,000 pairs of the shoe so quickly last spring that it is rushing out 30,000 additional pairs, which should hit store shelves in February. Nike also makes a similar model, called Nike Free, whose thin soles were designed for barefoot training.
Dr. Mary Beth Crane, spokeswoman for the American College of Foot and Ankle Surgeons, says only people college-age or younger should run without shoes because older joggers "don't bounce as well", and that even youngsters should limit barefoot training to grass under strict supervision. Among other dangers, she says, is a "very real potential" for foot infections.
Barefooters counter that, just as casts atrophy muscles, shoes weaken feet. Because barefoot running flexes the arches more than shod running, it builds up a matrix of tiny muscles between the sole and the ankle. Lack of use of those muscles, caused by wearing thick-soled shoes and arch supports _ is considered by some doctors to be a main cause of ankle injuries and plantar fasciitis, a common foot ailment.
"A lot of this shoe support stuff just makes your foot lazy and puts your foot muscles to sleep," says Dr. Irene Davis, a biomechanics researcher and director of the University of Delaware's Running Injury Clinic.
Barefooters also try to minimize pain and stress on their feet by changing their running style. They land on the balls and arches of their feet, rather than their heels as shod runners do, because the middle part of the foot is more flexible and absorbs much of the shock when the foot strikes the ground.
The ideal sole is thick and smooth from heel to toe with few cracks and crevices. That leaves little room for fungi and parasites to hide.
Rick Roeber, a Kansas City runner who's run 11 marathons and a 40-mile race this year, all in bare feet _ says his soles are "like leather, almost like a moccasin shoe." But getting there wasn't easy. "I used to lie awake at night just from the pain of my blisters," he says.
To facilitate toughening, he tried "a bunch of wild and crazy stuff," including applying fingernail hardener to his soles and wrapping his feet in duct tape while running. The hardener didn't help, while the tape unraveled after a couple of miles.
In time, he says, his feet got used to "the new barefoot me." Now he makes sure that he shifts his center of gravity slightly forward so that he lands on the balls of his feet as softly as possible. As if in rehab, Mr. Roeber proudly declares, "I've been 952 days, shoe free."
Not all runners are barefoot believers. "I'm sticking to my Asics Tigers," says Neil Murphy, a New York attorney who tried running without shoes through the streets of Brooklyn earlier this year after a friend recommended it. A barrage of nicks, cuts and bruises led him to declare recently, "Humans are too far up the evolutionary chain to be trying this kind of stuff."