The effect of anterior cruciate ligament reconstruction on lower extremity relative phase dynamics during walking and running.

The purpose of this investigation was to use relative phase dynamics to evaluate gait in individuals with a reconstructed anterior cruciate ligament (ACL) during walking and running. Relative phase dynamics can describe the coordination strategies between the interacting segments at the lower extremity. Ten subjects who had undergone ACL reconstruction using the central third of their patellar tendon and ten healthy controls walked and ran on a treadmill at a self-selected pace.

Modeling dynamic resource utilization in populations with unique constraints: preadolescents with and without Down syndrome.

In this study we used a damped inverted pendulum and spring with an escapement function model to compare the global levels of stiffness and forcing used by 12 preadolescents with Down syndrome (DS) and 12 with typical development (TD). Participants walked overground at their self-selected speed and on a treadmill at speeds slower and faster than overground. Children with DS, who are characterized as hypotonic with reduced capacity for producing muscle force, exhibited significantly higher levels of stiffness and forcing (angular impulse) when walking on the treadmill and higher forcing but not stiffness overground, than children with TD.

Dynamic stability of gait cycles as a function of speed and system constraints.

The purpose of this study was to examine the dynamic stability of two groups of children with different dynamic resources in changing contexts. The stability of the lower extremity segments of preadolescent children (8-10 years old) with and without Down syndrome (DS) was evaluated as children walked on a motorized treadmill at varying speeds. Tools from nonlinear dynamics, maximum Lyapunov exponent, and approximate entropy were used to assess the behavioral stability of segmental angular displacements of the thigh, shank, and foot.

Nonlinear dynamics indicates aging affects variability during gait.

Objective: To investigate the nature of variability present in time series generated from gait parameters of two different age groups via a nonlinear analysis.

Design: Measures of nonlinear dynamics were used to compare kinematic parameters between elderly and young females.

Background: Aging may lead to changes in motor variability during walking, which may explain the large incidence of falls in the elderly.