Athletes who sprain their ankle often report that the ankle feels like it’s going to give way, a symptom called functional ankle instability (FAI). Physical therapists and athletic trainers work with these athletes to restore normal ankle function and prevent recurrent sprains or other ankle injuries. It makes sense that anyone who feels this way is at risk for recurrent injuries. But are they really? That’s what the authors of this study tried to find out.
Physical therapists and athletic trainers from Indiana University and a nearby high school teamed up to test and compare a group of active college athletes with and without ankle instability to see just what was their functional ability. One group of 30 athletes was perfectly normal (no previous ankle injuries). They served as the control group.
The second group of 30 college athletes tested positive on the Ankle Instability Instrument (AII) for functional ankle instability (FAI). These athletes were considered the FAI group. The FAI group was divided into two separate groups based on whether or not the ankle actually gave way during the AII test. No one in the FAI group had active signs of inflammation (swelling, warmth, redness) at the time of this study.
They used four different hopping-on-one-leg tests to measure function and performance and to identify any deficits. The four tests included: 1) figure-of-8 hop, 2) side hop, 3) 6-meter crossover hop, and 4) square hop. Everyone watched a videotape of these tests with a narrator describing exactly how to do each one. Each athlete was allowed to practice the hopping test skills (three trials each) before taking the test. The figure-of-8 test involved hopping on one foot in a figure-8 pattern around two cones set five meters apart (about 15 feet). The pattern was repeated two times as fast as possible.
The side-hop test required the test subject to hop on one foot sideways 30 centimeters (eight inches) and back 10 times (also as fast as possible). The six-meter crossover hop test required the athlete to hop over a four-inch wide line from the right side to the left side and back along a path that was eight feet long.
And finally, in the square hop test, a 10-inch by 10-inch square of tape was placed on the floor. The subjects had to hop in and out of the square all the way around (clockwise for the right leg/counterclockwise for the left leg). Each of the four tests was repeated three times and each trial was timed. The athletes in both groups were asked if the ankle on the hopping side felt unstable during any of the trials.
The control group had no trouble completing any of the tests on either leg. The FAI group had the most trouble with the figure-of-8 and side hop tests. There were reports of a sensation of giving way in the FAI group for the figure-of-8, crossover hop, and square hop tests. Even when all four tests could be completed, there was a difference between the side of the ankle injury and the uninjured side (slower times needed to complete tests on the involved leg). And as might be expected, for athletes in the FAI group who experienced a sensation (or actual) giving way of the injured ankle, the results of their tests were slowest of all the participants.
In any of the trials, if the athlete fell, missed the stopping point, hopped in the wrong direction, didn’t hop all the way over the line, or put the other foot down, the trial was invalid and they had to do it over. Remember, the whole idea behind this study was to find a way to identify who really needs rehab after an ankle injury and when they are ready to return-to-play safely.
The authors also pointed out that the hopping tests they used require more than just muscle strength. Speed, coordination, and agility are important components of these tasks. And testing an athlete’s agility is critical to the return-to-sports decision, especially for activities that require cutting and changing directions quickly. Moving with speed in different directions is a prime ingredient in functional sports performance.
So, can these tests be used to predict who can get back on the field and who needs more rehab? Maybe. The differences between the FAI group and the control group weren’t so broad that the authors could categorically say Yes, these hopping tests gave all the information needed to make the return-to-sport decision. The group most likely to need further help was the group who self-reported ankle instability (giving way).
But even within this group, there was a wide range of hopping ability and variable amounts of ankle instability. The authors conclude that just asking about the presence of instability isn’t enough. The two tests that provided the most accurate indicator of trouble ahead were the ones that stressed the side of the ankle where the original injury had occurred (figure-of-8 and crossover hop). Oh yes, and in case anyone is wondering — they did analyze whether or not leg dominance affects the performance of these tests and found that it was not a critical factor in the results. This finding was based on the fact that function and performance were equally good on both legs for the control group.
More research is needed in this area. But for now, it seems reasonable that the hop tests described here can be used to identify problems in athletes with known functional ankle instability (FAI). The same tests can give therapists and athletic trainers a better idea of athletes’ progress in rehab. And these hopping tests might prove very useful when prescreening athletes for possible ankle instability. Preventing ankle sprains makes a whole lot more sense than always retraining and rehabilitating athletes who have ankles that give way under them when in the heat of sports action.