UF Study: Ankle Strength May Not Be Key To Preventing Chronic Sprains

November 10, 1999

GAINESVILLE — Doctors, athletic trainers and physical therapists should alter their treatments for people who suffer frequent ankle sprains rather than rely on extensive strength training during rehabilitation, according to a new University of Florida study.

Lack of ankle strength may not be what causes 60 percent of people who have sprained their ankle once to sprain it again, said Tom Kaminski, an assistant professor in UF’s department of exercise and sport sciences. Instead, it may be that an ankle is more prone to future injury because of a small neuromuscular change sustained during the initial injury.

“In order for a muscle to fire correctly, it has to have an intact nerve,” Kaminski said. “The nerve carrying the message from the ankle to the brain may have been disrupted as a result of the injury, and you might move your ankle somewhat differently because of that.”

The finding could have widespread effect. About 1 million people in the United States sprain their ankles annually, according to the journal American Family Physician.

“People look at ankle injuries as being no big deal, and in many cases, this is the traditional viewpoint,” Kaminski said. “Because of that, not many people research this area, but it’s very important because of the large occurrence of ankle sprains in the general population.”

The finding that strength training alone isn’t enough to rehabilitate an ankle could change the way clinicians advise patients in rehabilitation, Kaminski said, because it calls into question the popular and long-held belief that muscle strength is the key to successful prevention of future sprains.

“This type of thought is cutting-edge,” Kaminski said. “We’ll see the explosion of this in the next five to 10 years.”

Kaminski’s study, which was published in September’s Journal of Athletic Training, used 42 subjects, half of whom had experienced chronic functional ankle instability, which is the repeated injury of a previously sprained ankle, at the time of the study. A control group was created by pairing each subject with another person of similar age, build and activity level.

Using an isokinetic dynamometer, a device that measures muscle strength, Kaminski tested each subject in a series of motions, all of which turned the sole of the foot outward. He chose eversion motions because they are required to balance out the tendency of the foot to turn inward during an ankle sprain, which is the case in 90 to 95 percent of sprains, Kaminski said. There was no significant difference between the ankle strength of subjects who suffered repeated ankle injuries and those who did not, he said.

“If a clinician finds that a patient’s ankle is strong, they may not be helping them by doing strengthening exercises alone,” Kaminski said.

People who suffer from repeated ankle sprains should talk to their physicians about neurological training in addition to strength training, Kaminski said.

“You may have to teach yourself to do things all over again, even if your ankle seems to be functional,” Kaminski said. “Learning to re-train movements a bit may be the future of ankle rehab.”

Effective rehabilitation is vital to the prevention of future damage to the ankle, said Glenn Pfeffer, an orthopedic surgeon in San Francisco and secretary of the Seattle-based American Orthopaedic Foot and Ankle Society.

“The most significant risk factor for a severe ankle sprain is having had a sprain already,” he said. “Appropriate rehabilitation will go a long way in preventing repeated sprains and possible permanent soft tissue or cartilage damage to the ankle.”