NEUROMUSCULAR CONTROL DURING PERFORMANCE OF A DYNAMIC BALANCE TASK IN SUBJECTS WITH AND WITHOUT ANKLE INSTABILITY.
METHODS
Cross-sectional, controlled laboratory study.


BACKGROUND
Lateral ankle sprains are common injuries and often lead to chronic ankle instability (CAI). Individuals who previously sustained a lateral ankle sprain, but did not develop CAI, termed copers, may have altered postural control strategies compared to individuals who have developed CAI. These altered postural control strategies may allow for more appropriate dynamic stabilization of the ankle joint after injury compared to those seen in patients who have developed CAI.


OBJECTIVE
To compare lower leg biomechanics, as well as electromyographic (EMG) activation of the tibilias anterior and peroneus longus muscles, during the posteromedial reach of the Star Excursion Balance Test (SEBT) in individuals with healthy ankles, copers, and those with CAI.


METHODS
30 participants (12 control, 9 copers, 9 CAI) divided into three groups based on ankle sprain history and Cumberland Ankle Instability Tool score. Kinematic, kinetic, and EMG data were collected during three posteromedial reach trials on the SEBT.


METHODS
Primary outcome measures include SEBT normalized reach distance in the posteromedial direction and average integrated EMG activation of the tibialis anterior and peroneus longus muscles during the reach. Secondary outcome measures included sagittal and frontal plane ankle complex angles and moments and sagittal plane knee angles and moments. Data were analyzed between groups using a one-way ANOVA model.


RESULTS
No significant differences in reach distance or kinematic and kinetic outcomes were found between groups. The activation of the tibialis anterior and peroneus longus muscles was significantly different between groups (p=0.033 and p=0.014, respectively). The post-hoc analysis revealed that the coper group had significantly higher muscle activation compared to the control group, but not to the CAI group.


CONCLUSIONS
CAI did not alter kinematic, kinetic, or reach performance during the SEBT. When compared to controls, copers appeared to have greater activation of the ankle musculature, which may increase stability of the ankle complex during a dynamic balance task.


METHODS
Prospective Cohort level II.
Biomechanics and Movement Science Program, University of Delaware, Newark, DE, USA.
Federico
F
Pozzi
Department of Physical Therapy, New York University, New York, NY, USA.
Marilyn
M
Moffat
Department of Physical Therapy, New York University, New York, NY, USA.
Gregory
G
Gutierrez
Copers; Star Excursion Balance Test; electromyography; motion analysis