![]() To evaluate this hypothesis, we developed a new method to extract invariant spatiotemporal components from the simultaneous recordings of the activity of many muscles. Muscle synergies-coherent activations, in space or time, of a group of muscles-have been proposed as building blocks that could simplify the construction of motor behaviors. The many degrees of freedom of the musculoskeletal apparatus provide great flexibility but make the control problem extremely complex. However, data do suggest that sagittal hip and knee strategies are recruited more than ankle and frontal hip strategies during SLST.A central issue in motor control is how the central nervous system generates the muscle activity patterns necessary to achieve a variety of behavioral goals. It is not currently possible to correlate COPE velocity to a specific synergy group recruitment. CONCLUSION: There is insufficient evidence to claim that muscle group activations are different depending on fall risk grouped by COPE velocity. Negligible and insignificant correlations were found between frontal hip and sagittal hip synergies and COPE velocity ((r = 0.013, -0.068, p = 0.475, 0.367). Weak and negative correlations were found between COPE velocity and both knee and ankle groups (r = -0.309, -0.323, p = 0.059, 0.050). Low fall risk group was found to have significant differences between the sagittal hip and frontal hip groups (p = 0.038) and frontal hip and knee groups (p = 0.012). The ANOVA and Tukey post-hoc tests for high fall risk group found significant differences in co-activation index value between the sagittal hip and frontal hip groups (p = 0.022) and sagittal hip and ankle groups (p = 0.016). RESULTS: No significant differences in muscle synergy between the high and low fall risk groups were found (p = 0.476, 0.076, 0.064, 0.364). A Pearson correlation analyzed COPE velocity and co-contraction index value. Nonparametric Analysis of Variance (ANOVA) and Tukey post-hoc tests were run on the high and low fall risk groups separately to determine differences in co-contraction index value within high and low fall risk groups. An independent t-test was run on muscle synergy groups between high and low fall risk groups. Co-contraction indices were determined from linear envelopes plotted from muscle group EMG data. Muscle synergy groups were determined by common muscle pairings at the hip, knee and ankle. Balance ability was determined by COPE measurements during a SLST on a force plate. METHODS: Fall risk grouping was determined by average COPE velocity values calculated from previously reported fall frequency groups. It was hypothesized that i) co-contraction index values will differ between high and low fall risk groups, ii) there will be preferential activation of different synergy groups within the high and low fall risk groups, and iii) there will be a negative and direct correlation between COPE velocity and co-contraction index values for all synergy groups. The current study aimed to determine if the fall risk calculated by COPE velocity in children with CP is correlated with co-contraction index value in various muscle synergy groups. A recent study has correlated increased COPE velocity with a lower fall risk as determined by reported fall frequency, suggesting a more objective measure of fall risk. Center of pressure excursion (COPE) measurements collected during a single leg standing test (SLST) have shown to be more valid measurements of balance in populations with motor disabilities than a SLST alone. Motor coordination exhibited as co-contraction, has been subjectively quantified using gait analysis, but recent studies have begun to objectively analyze the amount of co-contraction by collecting electromyography (EMG) data. INTRODUCTION: Cerebral Palsy (CP) is a sensorimotor disorder characterized by dysfunctional motor coordination, balance problems, and loss of selective motor control.
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