Low-tech balance training decreases ankle sprain risk

The resources gap between the haves and the have-nots in youth sports is formidable. Columnist Rick Reilly's tale of two sixth-grade basketball teams in the March 12 issue of Sports Illustrated is a juxtaposition in point: the Texas Titans travel to tournaments on a private jet, stay in four-star hotels, and have meals planned by a trainer-nutritionist, while members of the D.C. Assault have to cram into a coach's minivan, eat at KFC, and share beds in fleabag motels where sometimes they're afraid to even sleep under the covers.

If a team's resources-or lack thereof-have this kind of effect on basics like eating and sleeping, you can be sure they also register an impact on injury prevention. Told that a number of studies have suggested that proprioceptive training can help prevent ankle sprains in adult athletes, a team like the Titans would likely spare no expense to give its athletes access to sophisticated computerized balance training equipment, not to mention skilled practitioners to implement the training.

Many, if not most, teams of young athletes don't have those kind of resources. They don't have money for special equipment or full-time trainers. And in many cases, time spent on preventive training programs is time taken away from practice.

"If the coach buys in and the school buys in, the kids will buy in. But coaches aren't being evaluated on how many injuries they're preventing," said Tim A. McGuine, PhD, ATC, senior athletic trainer and research coordinator at the University of Wisconsin's Health Sports Medicine Center in Madison.

That's why McGuine and others are focusing their efforts on developing balance training interventions that are inexpensive and can be easily incorporated into a team's practice schedule. Low-tech though they may be, research suggests that such training programs can significantly reduce rates of ankle sprain in high school football, basketball, and soccer players who are at increased risk of injury.

Grown-up ideas

The idea of using balance training to prevent ankle sprains is not new. More than two decades ago, a Swedish study published in the July-August 1985 issue of the American Journal of Sports Medicine found that ankle disk training significantly reduced the ankle sprain rate in 65 soccer players who had a history of ankle injury. In a study published in the June 1997 issue of the Scandinavian Journal of Medicine & Science in Sports, members of the Norwegian Volleyball Federation who had a history of ankle sprain experienced half as many injuries per 1000 player hours following the implementation of a prevention program that included balance board training. In the February 1999 issue of the same journal, Danish researchers reported a significant decrease in traumatic and overuse injury rates in handball players associated with use of a 10-month intervention that included 10 to 15 minute ankle disk sessions at all practices.

More recently, in a study published in the April 2004 issue of the British Journal of Sports Medicine, Greek investigators found that a season of proprioceptive training significantly reduced the incidence of ankle sprain in volleyball players. In research published in AJSM five months later, another Netherlands volleyball study found that a balance board training program significantly reduced rates of ankle sprain in those with a history of such injuries.

All of those studies, however, involved adult elite athletes. That their findings could be extrapolated to a younger, less skilled athlete population was not a foregone conclusion.

Test scores

In a 2000 study published in the Clinical Journal of Sports Medicine, McGuine and colleagues had documented that postural sway, as measured using a NeuroCom balance device during the first two weeks of two consecutive seasons, was associated with risk of ankle injuries in 210 high school basketball players during the course of those two seasons. The athletes who sustained ankle sprains had a preseason composite postural sway score of 2.01 plus/minus 0.32, while those who remained injury-free had a postural sway score of 1.74 plus/minus 0.31; those in the group with the highest postural sway scores were seven times more likely to sprain an ankle than those in the group with the lowest scores.

These findings, incidentally, were supported by those published last summer in the June issue of the Archives of Physical Medicine & Rehabilitation. Investigators from National Taiwan University in Taipei used force plate measurements to assess balance in 42 high school basketball players, then documented ankle sprain rates throughout the season using monthly questionnaires sent via the mail. They found that high levels of variation in postural sway were associated with significantly increased rates of ankle injury. Like the Wisconsin findings, these results suggest that balance training would, in fact, be an appropriate intervention for preventing ankle sprains in the high school athlete population.

To further test this theory, the Wisconsin researchers randomized 764 high school soccer and basketball players of both genders to either a balance training intervention group or a control group that performed only the conditioning exercises mandated by their coaches. The balance training program began with a four-week preseason regimen, involving five sessions per week, in which subjects initially performed the balance tasks on the floor but progressed to a balance board. During the season, the program involved three 10-minute sessions per week. Tasks included single leg stance with eyes open and eyes closed, single leg stance while performing sport-specific activities (e.g., dribbling a basketball or kicking a soccer ball against a wall), and double leg stance while rotating on the balance board; each task was performed for 30 seconds.

During the season, the overall rate of ankle sprain was 1.51 per 1000 exposures; those in the intervention group had a significantly lower rate than those in the control group (1.13 per 1000 versus 1.87 per 1000). Other than balance training participation, the only variable that contributed to risk of sprain was history of sprain.

In athletes without a history of ankle sprain, the rate of injury in the intervention group was lower than in the control group (12 of 284 intervention versus 23 of 299 controls); although not statistically significant, that difference did approach significance (P = .059). Given the challenge of enrolling enough study subjects to achieve statistical significance in those without a history of ankle sprain, McGuine believes balance training should be implemented in all young athletes, not only those known to be at risk.

"It's a strong trend, and doesn't make you not want to do it," he said. "There's no indication that it's putting kids at risk, so why not have all the kids do it?"

Weighty issues

Meanwhile, researchers at the Nicholas Institute of Sports Medicine and Athletic Trauma (NISMAT) in New York City were approaching the same challenge from a different angle. Whereas the Wisconsin researchers had linked ankle sprain risk to balance deficiencies assessed using a high-tech method, the NISMAT team felt that a simpler, less expensive method of balance assessment might be easier to implement at the high school level.

In 169 high school athletes (male football players, female gymnasts, and basketball and soccer players of both genders), the researchers analyzed balance by determining the time out of balance each athlete spent on a tilt board during a one-minute single leg stance test with arms folded across the chest. A switch attached to the contralateral foot signaled whether movement of that foot was being used to maintain balance; time out of balance was defined as the time when the switch was activated.

The researchers found that balance ability, as measured this way, was not predictive of ankle sprain risk in their study population.

"The balance test we used may not have been a sensitive measure of balance," said Malachy P. McHugh, PhD, director of research at NISMAT and lead author of the study, which was published in the March 2006 issue of AJSM. "We were looking for something that could be used for mass screening, which is not feasible with a force plate."

History of ankle sprain, not surprisingly, was one predictive variable. The other predictive variable was body mass index (BMI): injury incidence among the overweight male athletes in the study group was significantly higher than in the rest of the male athletes (3.0 versus 0.8 sprains per 1000 exposures), and higher still in those who were overweight and also had a history of ankle sprain (5.58 per 1000).

Because all of the overweight athletes from the multisport study were football players, the researchers then retested the BMI hypothesis in a second, 152-subject study of athletes from four high school football teams. This second study, which was published in the same issue of AJSM, confirmed the findings of the first: incidene of ankle sprain was significantly higher in players who were overweight (2.03 per 1000 exposures) or at risk of being overweight (1.05 per 1000) than in those with a normal BMI (0.52 per 1000). Overweight players with a history of ankle sprain were 19 times more likely to sustain an ankle sprain than normal-weight players with no history of sprain. (Overweight was defined as being in the 95th percentile or higher according to the Centers for Disease Control and Prevention; at risk of overweight was defined as being between the 85th and 95th percentiles.)

Pad performance

Having identified those two predictive variables, the researchers then tested the effectiveness of an intervention-again, the objectives being convenience and affordability-that could be used as a preventive measure specifically in athletes who were overweight, had a history of ankle sprain, or both. They followed 84 players for up to two seasons prior to implementing the intervention and 125 players for as many as three seasons following the implementation, with players assigned to risk groups prior to each season based on BMI and history of ankle sprain. Those who were overweight, at risk of being overweight, and/or had a history of injury were included in the intervention group; those who were normal weight and had no history of ankle sprain served as a control group.

The balance training involved single limb standing on a foam stability pad (more portable and less expensive than an ankle disk) with eyes open for five minutes at a time on each leg, five days per week during a four-week preseason period and twice per week for nine weeks during the football season. The teams were able to incorporate the balance training into their normal training sessions by adding a balance "station" to their regular weight-room circuit, according to Timothy F. Tyler, PT, senior physical therapist and clinical education coordinator at NISMAT, who presented the study's results in February at the American Physical Therapy Association's annual Combined Sections Meeting.

For all players in the intervention group, the incidence of ankle sprain decreased significantly from 2.2 per 1000 exposures preintervention to 0.5 per 1000 exposures postintervention-a 77% reduction. Injury incidence did not change significantly for players who were not included in the intervention.

Finding the balance

The findings, which are slated for publication in AJSM, suggest that stability-pad training not only addresses underlying balance impairments in athletes who have a history of ankle sprain, it may also enable heavier players to more effectively negotiate changes in momentum that can contribute to injury. This may be a particularly important finding in football, where for many players the notion of decreasing injury risk through weight loss is just not practical.

"It's a lot easier to have someone balance for 10 minutes several days a week than to have them diet," McHugh said.

Indeed, the success of any preventive measures in youth athletes may depend on ease of implementation, which goes a long way toward winning over coaches and players. The only way to get total buy-in, though, may be for researchers to demonstrate that balance training not only decreases injury risk but also improves performance.

"If we could claim that balancing would increase your free throw percentage by fifteen points, then they'd all be doing it," McGuine said.

Jordana Bieze Foster is a freelance medical writer in Massachusetts and a former editor of BioMechanics.