A new study shows that people take shorter strides while walking in rubber slippers to keep them from flying off, which could lead to lower leg and feet problems.

But just try getting Hawai'i folks like Bob Becker to give up the worn-down pair of $1.99 slippers he buys at Foodland.

Becker, a 58-year-old construction worker from 'Ewa, even wears his slippers on the job and has dropped tools and materials on his toes and had screws and nails pop through the soles of his size-12 slippers.

Somewhere, in the back of his slipper-loving mind, Becker's always wondered if wearing slippers so much could lead to foot and leg injuries.

"But I have a hard time putting anything else on," Becker said. "I feel so confined wearing shoes."

The study by researchers at Auburn University in Alabama looked at 20 women and 19 men ages 19 to 25. They were videotaped in athletic shoes walking across a platform that measures force and then videotaped again — on a separate day — wearing slippers.

The result: People took shorter strides in slippers, or "flip-flops," as the study called them.

"We think you're using your toe to grip the flip-flop as you swing your leg through the stride," said the study's author, Justin Shroyer, a doctoral candidate in Auburn's department of kinesiology. "You don't want to kick your foot out as much and you're scrunching your toe, so you're actually taking more steps to go the same distance compared to walking in tennis shoes. Anytime you change your gait from normal, it's going to put a different stress on the lower legs and feet that they're not used to."

An abstract of the study was presented last month at the annual meeting of the American College of Sports Medicine in Indianapolis.

One of its recommendations — that slippers be thrown out every three to four months — also runs counter to a Hawai'i culture accustomed to people wearing the same pair for years and even patching them with duct tape.

"When the material is broken down and no longer provides the support and cushion that it once did, it's time to throw them out," Shroyer said.

INSPIRED RESEARCH

Shroyer, 27, is a personal trainer, distance runner, mountain biker and former high school athlete who enjoys wearing slippers in Alabama's heat and humidity.

"I have very flat feet and fallen arches," Shroyer said. "Wearing flip-flops with no arch support is not helping my foot structure. It's actually going to make it worse, or at least not correct it."

He decided to study the effects of slippers while working on his doctoral dissertation about athletic footwear and heard complaints about lower leg problems from members of Auburn's marching band.

"They showed up in flip-flops and then changed into standard closed-toe shoes for practice," Shroyer said. "As soon as they were finished, they'd change back into flip-flops. They're small and can easily fit into a bag — the ease of getting them on and off — and when your feet swell and they're hot, flip-flops are comfortable."

Shroyer's research found anecdotal references to abnormal changes connected to wearing slippers.

"But I believe I'm the first person to actually collect kinetic data on people walking with flip-flops," he said.

Shroyer has never been to Hawai'i and is unsure what the study means for an island population that grew up wearing slippers.

But he's certain it could provide important information for tourists who find themselves temporarily switching from their usual footwear to slippers for a week or two.

Eileen Dees, a real estate consultant, lives part-time in Bend, Ore., and part-time in Waikoloa on the Big Island.

"My feet always hurt when I wear flip-flops and my legs get sore," Dees said. "I need shoes with arches."

PREVENTABLE PROBLEMS

Dr. Garret Noguchi, a podiatrist at Kuakini Medical Plaza, sees both locals and tourists with arch and heel problems related to improper footwear.

"Those $1.99 slippers from Wal-Mart or Longs cause a lot of problems," he said. "It's preventable by proper footwear."

Up to 40 percent of Noguchi's clients complain of heel pain or plantar fasciitis, inflammation of the plantar ligament under the arch of the foot. Some 60 percent to 70 percent of those patients' problems appear connected to wearing slippers.

"I get tourists who come in with terrible pain," Noguchi said. " 'What have you been doing? Just going to the beach every day.' They're not used to that. They're used to wearing shoes all the time, even in the house."

But his recommendations are the same for local residents and visitors.

"I first tell them, 'Change your footwear. Don't wear slippers all the time,' " Noguchi said. "You've got to go back to athletic shoes or proper footwear, not flats. And rest. It is an injury."

Dr. Spencer Chang, an orthopedic surgeon at Straub Hospital and the University of Hawai'i's pole vault coach, does not believe there is a strong connection between wearing slippers and foot and leg problems.

"There are going to be different gaits when walking with shoes or slippers or barefoot," Chang said. "Is that detrimental? Not necessarily."

Chang attended 'Iolani School, where he went barefoot because slippers were not allowed. He acknowledges that he walks differently in slippers.

"I do have to grip them," he said. "It does affect your gait a little bit. But I would not, because of a study, stop using slippers. That's crazy."

So people like Big Island construction worker Thomas McIlvain of Waikoloa have found a middle ground.

"My feet and knees have been hurting for 20 years," McIlvain said. "The balls of the feet, toes, swelling."

Then in October, for his 45th birthday, a friend gave McIlvain a pair of high-end slippers with arch support.

The size-10 1/2 slippers were perfect for McIlvain and his problems.

"My knees feel better, my feet feel better," McIlvain said. "I love these slippers. I'm never getting another pair."

"I can see wearing them (slippers) would be a problem if you're used to wearing sneakers. I don't notice any difference because I wear them all the time at home."

"Some of our friends say their feet are sore — their heel and in between their toes."

"I've got a bad heel, and the regular slippers hurt. There's no support."

RAYNETTE BECKER | PAINTER, 'EWA

"You walk different (in slippers), especially in the sand. My calves get tighter. It feels like shin splints."

"Wear good-quality slippers with proper arch and ankle support."

STUDY FINDINGS

Researchers found that walking in slippers may change one's normal gait, which can result in problems and pain to the foot up into the hip and lower back.

Slipper wearers took shorter steps

Heel hits the ground with less force

Do not bring their toes up as much during the leg's swing phase, which results in a larger ankle angle and shorter stride length.

The study tested 39 participants who walked on a force platform; each had three trials alternating each day between slippers and sneakers.

Source: Auburn University study

See slippers, A2