Validating stroke-induced bilateral ankle coordination deficits using bilateral ankle measure relationship with motor functions in lower limbs.

BACKGROUND: Coordinated control between the bilateral ankle joints plays an important role in performing daily life functions, such as walking and running. However, few studies have explored the impact of stroke on movement disorders that decrease the coordination control of the bilateral extremities and may decrease daily activities that require coordination control of the bilateral ankles. This study aimed to investigate the coordination control of the bilateral ankles using a novel bilateral ankle measurement system and evaluate the relationship of bilateral movement coordination control deficits with motor and functional performances of the lower extremities in patients with stroke. METHODS: Twenty-one healthy adults (36.5 ± 13.2 y/o) and 19 patients with chronic stroke (58.7 ± 10.5 y/o) were enrolled. A novel measurement device with embedded rotary potentiometers was used to evaluate bilateral ankle coordination control. Participants were asked to move their dominant (non-paretic) foot from dorsiflexion to plantarflexion position and non-dominant (paretic) foot from dorsiflexion to plantarflexion position (condition 1) simultaneously, and vice versa (condition 2). Alternating time and angle for coordination control with movements of both ankles were calculated for each condition. Motor and functional performance measurements of the lower extremities included the lower-extremity portion of the Fugl-Meyer assessment (FMA-LE), Berg Balance Test (BBS), Timed Up and Go Test (TUG), and Barthel Index (BI). RESULTS: Compared with the healthy group, alternating time was shorter in the stroke group by 8.3% (p = 0.015), and the alternating angles of conditions 1 and 2 were significantly higher than those of the healthy group by 1.4° (p = 0.001) and 2.5° (p = 0.013), respectively. The alternating angle in condition 2 showed moderate correlations with TUG (r = 0.512; p = 0.025), 10-m walk (r = 0.747; p < 0.001), gait speed (r = - 0.497 to - 0.491; p < 0.05), length (r = - 0.518 to - 0.551; p < 0.05), and BI (r = - 0.457; p = 0.049). CONCLUSION: Stroke decreases alternating time, increases alternating angle, and shows bilateral ankle coordination control deficits temporally and spatially. A higher alternating angle is moderately to highly associated with motor function and lower limb function in patients with stroke.

Analysis of Vibration Frequency and Direction for Facilitating Upper-Limb Muscle Activity.

We aimed to determine the effect of vibration frequency and direction on upper-limb muscle activation using a handheld vibrator. We recruited 19 healthy participants who were instructed to hold a handheld vibrator in their dominant hand and maintain the elbow at 90° flexion, while vertical and horizontal vibrations were applied with frequencies of 15, 30, 45, and 60 Hz for 60 s each. Surface electromyography (EMG) measured the activities of the flexor digitorum superficialis (FDS), flexor carpi radialis (FCR), extensor carpi ulnaris (ECU), extensor carpi radialis (ECR), biceps, triceps, and deltoid anterior muscles. EMG changes were evaluated as the difference in muscle activity between vibration and no-vibration (0 Hz) conditions. Muscle activity was induced under vibration conditions in both vertical and horizontal (p < 0.05) directions. At 45 Hz, FDS and FCR activities increased during horizontal vibrations, compared with those during vertical vibrations. ECU activity significantly increased under 15-Hz vertical vibrations compared with that during horizontal vibrations. Vibrations from the handheld vibrator significantly induced upper-limb muscle activity. The maximum muscle activations for FDS, ECR, ECU, biceps, and triceps were induced by 45-Hz horizontal vibration. The 60-Hz vertical and 30-Hz horizontal vibrations facilitated maximum muscle activations for the FCR and deltoid anterior, respectively.