May 2014

Poor dynamic postural stability predicts risk of ankle injury in ball team athletes

iStock_000018439322_smBut exercises may not help those with CAI

By Jordana Bieze Foster

Poor dynamic ankle stability is predictive of injury risk in athletes, but exercises designed to improve dynamic balance may not be effective in athletes with chronic ankle instability, according to separate studies presented at the IOC conference in Monaco.

Investigators from the University Medical Centre Groningen in the Netherlands assessed dynamic postural stability and drop jump-landing technique in 42 athletes (mean age, 22.2 years) who played basketball, korfball, or volleyball at an elite level and tracked knee and ankle injury rates for one year. Dynamic postural stability index (DPSI) scores, with high scores indicating poor stability, were based on mediolateral, anterior-posterior, and vertical stability (time to stabilization) associated with single-leg jump landings onto a force plate in frontal, diagonal, and lateral directions. Drop-landing technique was assessed using the Landing Error Scoring System (LESS; higher score reflects poorer technique).

One year later, the Dutch researchers found that athletes who went on to suffer an ankle injury had significantly higher baseline DPSI scores for diagonal anterior-posterior, diagonal vertical, and lateral anterior-posterior components than those who had no ankle injuries. Athletes who went on to sustain a knee injury had higher baseline LESS scores than those with no knee injuries, but that difference was not statistically significant.

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Those findings suggest there may be an opportunity for intervention, such as balance exercises, to prevent ankle injuries in athletes with elevated DPSI scores. But a Belgian study presented at the IOC conference found that balance training did not significantly improve DPSI scores in recreational athletes with chronic ankle instability (CAI).

In 64 recreational athletes, 33 of whom had chronic ankle instability, researchers from Ghent University assessed DPSI before and after a home-based progressive balance exercise program. Athletes performed exercises three times per week for eight weeks. Progressions included adding arm movements, going from eyes open to eyes closed, and decreasing the stability of the exercise surface.

Baseline DPSI scores confirmed that dynamic postural stability was significantly poorer for the athletes with CAI than the controls, as were self-reported functional scores on the Foot and Ankle Disability Index (FADI). After the intervention, the FADI scores had improved significantly in the CAI patients, but the DPSI scores had not.

It may be that the balance exercises were not specific enough to improve dynamic measures, or that the DPSI was not sensitive enough to detect more subtle degrees of improvement, according to Roel De Ridder, a doctoral student in the Department of Physical Therapy and Motor Rehabilitation at the university, who presented his group’s findings in Monaco.

“I think athletes should do balance training, but to improve postural control we have to potentially think about incorporating other exercises or training techniques,” De Ridder said.

Another study from the same Belgian group may shed some light on the landing kinematics underlying the postural control deficits seen in athletes with CAI. In 96 recreational athletes, De Ridder and colleagues found that those with CAI had a stiffer landing technique during vertical drop jumps and side jumps than controls or “copers” who had a history of ankle sprain but did not have ongoing instability. A multisegmented foot model further distinguished CAI patients from copers, who demonstrated less plantar flexion and dorsiflexion range of motion in the lateral and medial forefoot.

Sources:

Van der Does H, Brink M, Lemmink K. A one year prospective study on ankle stability and landing technique: The occurrence of ankle and knee injuries in elite ball team athletes. Br J Sports Med 2014;48(7): 586.

De Ridder R, Willems T, Vanrenterghem J, Roosen P. Effect of balance training on dynamic postural control in subjects with chronic ankle instability. Br J Sports Med 2014;48(7):584.

De Ridder R, Willems T, Vanrenterghem J, et al. Multi-segmented foot landing kinematics in subjects with chronic ankle instability. Br J Sports Med 2014; 48(7):584.

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