Variability of the co-contraction indexes of the lower limb in children with Down syndrome during the initial period of gait acquisition

Ana Paula Bensemann Gontijo
UFMG

Mancini Marica Cotta
UFMG

Sergio Fonseca Teixeira
UFMG

Raquel Etrusco Luz

Flavia Maia Barbosa

Paula Lanna da Silva

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     Last modified: March 6, 2007

Abstract
Objectives: The aims of this study were to evaluate the variability of the co-contraction indexes (ICC) of the hip, knee and ankle joints and a total lower limb index of children with DS during the initial period of gait acquisition. The hypotheses were that the variability of the muscular components, given by the ICC, would decrease during the period of the study, and that the variability coefficient (VC) of the ICC would be different between the three joints.
Methods: Twelve children with DS were followed during five consecutive assessments: on the week they started independent gait and fifteen, thirty, sixty and ninety days after the first assessment. The ICC of three muscle pairs of the right lower limb, and a total index, were calculated through the quantification of the electric signal of the surface electromyography. A significance level of 0,05 was considered.
Results: the results showed significant differences for the ankle joint for the assessments between days 0 and 90 (p=0,047) and between days 15 and 60 (p=0,004) and 15 and 90 (p=0,003). There was also a decrease on the VC of the ankle joint during the stance phase (p=0,001). There was no significant difference on the hip and knee joints and on the total index on the stance phase as well as no significant differences of the VC were found for any of the joints during the swing phase.
Conclusions: These results illustrate the importance of the exploration of different neuromuscular mechanisms for the selection and enhancement of more efficient strategies during the acquisition of a new skill.