Effects of chronic ankle instability on energy dissipation in the lower extremity.

PURPOSE

This study aimed to investigate the influence of chronic ankle instability (CAI) on lower extremity joint energy dissipation patterns during a stop-jump task.

METHODS

Nineteen participants with self-reported CAI and 19 healthy control participants volunteered. Participants performed five double-leg vertical stop-jump tasks onto a force plate. Lower extremity kinetics and kinematics were examined with an electromagnetic tracking system interfaced with a nonconductive force plate. Lower extremity joint energy dissipations were calculated for the hip, knee, and ankle in the sagittal plane during 50, 100, 150, and 200 ms after initial contact with the force plate. Energy dissipation values were normalized to the product of body mass and height [J · (N · m)(-1)]. Individual joint contribution to total lower extremity energy dissipation by the ankle, knee, and hip was reported as the percentage of energy dissipation by each joint over the total energy dissipation of all three joints. Independent t-tests and standard mean differences were conducted to assess differences in each dependent variable between the CAI and the control groups. Significance was set a priori at P < 0.05.

RESULTS

The CAI group demonstrated significantly less percentage of knee energy dissipation (P = 0.04) and higher percentage of ankle energy dissipation (P = 0.035) of the total energy dissipation during the 100 ms immediately after initial contact compared with the control group.

CONCLUSIONS

We found altered energy dissipation patterns at the knee and ankle during a stop-jump task in the CAI group. These findings may provide insight into kinetic alterations that may be associated with CAI. Future research should consider this information as it may be used to develop more effective interventions to target these potentially modifiable energy dissipation patterns in those with CAI.