RESUMEN
The aim of this study was to investigate anticipatory (APA), simultaneous (SPA) and compensatory (CPA) postural adjustments in individuals with and without chronic ankle instability (CAI) as they kicked a ball while standing in a single-leg stance on a stable and unstable surface. Electromyographic activity (EMG) of postural muscles and center of pressure (COP) displacements were calculated and their magnitudes analyzed during the postural adjustment intervals. Additionally, the COP area of sway was calculated over the duration of the whole task. The activities of postural muscles were also studied using principal component analysis (PCA) to identify between-group differences in patterns of muscle activation. The individuals with CAI showed reduced magnitude of EMG at the muscles around the ankle while around the hip the activity was increased. These were associated with a reduction in balance sway across the entire task, as compared with the control group. The PCA revealed that CAI participants assemble different sets of muscle activation to compensate for their ankle instability, primarily activating hip/spine muscles. These results set up potential investigations to examine whether balance control interventions enhance these adaptations or revert them to a normal pattern as well as if any of these changes proactively address recurrent ankle sprain conditions.
Asunto(s)
Articulación del Tobillo/fisiopatología , Inestabilidad de la Articulación/fisiopatología , Destreza Motora/fisiología , Músculo Esquelético/fisiología , Equilibrio Postural/fisiología , Desempeño Psicomotor/fisiología , Adulto , Articulación del Tobillo/fisiología , Enfermedad Crónica , Electromiografía , Femenino , Humanos , Masculino , Soporte de Peso/fisiología , Adulto JovenRESUMEN
Individuals with chronic ankle instability (CAI) usually experience deficits in balance control, which increase displacement in the body's center of pressure (COP) when they balance on a single leg. Little is known, however, about whether or not these individuals use the strategies of postural adjustment properly, especially during functional tasks that may predispose them to ankle sprain. The aim of this study was to investigate anticipatory (APA) and compensatory (CPA) postural adjustments in individuals with and without CAI as they kick a ball while standing in a single-leg stance with their ankle in neutral and supinated positions. COP displacements were calculated and their magnitudes (range) analyzed during APA and CPA intervals and over the duration of the whole task, represented by the COP area of sway and mean velocity. The CAI group exhibited a significant decrease in CPA and area of sway over the whole task, relative to controls. These results suggest that the decreased balance sway could be caused by the need for further stabilization of the ankle in more unstable postures to prevent recurrent sprain. Our findings could help clinicians to better understand the strategies of postural adjustments in individuals with CAI, and may assist and motivate new investigations into balance control interventions in such individuals, as well as proactively address recurrent ankle sprain conditions.