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Grimaldi Forum Monaco, Monte Carlo, Monaco 7–9 April 2011
Exploring dynamic stability in a group of intercollegiate athletes
  1. K Liu,
  2. G Gustavsen,
  3. T W Kaminski
  1. University of Delaware, Newark, Delaware, USA


Background Deficits in postural stability have been linked to an increased risk of ankle sprain. Repeated ankle sprains can lead to ankle instability. Time to stabilisation (TTS) has been used to measure dynamic stability.

Objective To determine if differences exist in TTS between stable and unstable ankles.

Design Controlled, cross-sectional.

Setting Biomechanics Laboratory.

Participants 64 Division I collegiate athletes (25 females and 39 males, age=18±0.9, height=180.5±10.3 cm, mass=82.5±18.9 kg).

Interventions Group status (stable vs unstable) was determined by the Cumberland Ankle Instability Tool (CAIT). Each participant completed hops onto a force plate from four different directions (forward, backward, medial, lateral) and were instructed to land in the middle of the force plate on a single leg, stabilise as quickly as possible, and remain motionless for 5 sec. Three trials were collected for each of the four directions. TTS was quantified as the time it takes the vertical component of the ground reaction force to reach and stay within ±5% of the participant's body mass after landing.

Main outcome measurements TTS (sec) data were analyzed using an independent t-test (p≤0.05) comparing the stable and unstable groups for each of the jump directions.

Results There were no significant differences in TTS (sec) between stable and unstable ankles.

Conclusion Contrast to other reports, our results indicate no difference in TTS between subjects that are classified as functionally stable and unstable. The CAIT determines functional instability without consideration for mechanical instability. Although not significant, it appears that the backward direction created the greatest discrepancy in TTS between the groups. We question the sensitivity of our TTS calculations as others have reported different techniques. Additional research is needed employing these refined methods.

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