Kinematics of treadmill stepping in Infants with Down Syndrome: Preliminary Results

Research Objectives: Down syndrome (DS) is a genetic disorder that causes significant motor, cognitive, and language delays. While typically developing (TD) infants begin to walk around 12 months of age, infants with DS begin to walk approximately around 24 months, thus delaying interaction with the environment and negatively impacting motor, social, and cognitive development. We have shown that early treadmill intervention can induce an early onset of walking and elicit better walking patterns. The preliminary results reported here are part of a comprehensive, longitudinal study in infants with DS who all receive an early treadmill intervention. Here we aim to understand the progress of joint biomechanics during treadmill stepping over time.

Design: Longitudinal, Interventional.

Setting: Home/natural environment.

Participants: 3 male infants with DS, mean age 10mo 9 days at Time 1 (i.e., entry into the study) and 12mo and 13 days at Time 2 (i.e., 3 months thereafter).

Interventions: Treadmill stepping.

Main Outcome Measures: Spatiotemporal and kinematic variables.

Results: All 3 subjects increased their step frequency between Time 1 and Time 2 (subject 1: 4.67 to 8 steps/min, subject 2: 1.33 to 3.33 steps/min, and subject 3: 5.67 to 20.33 steps/min). Also, from Time 1 to Time 2, subject 3 increased peak knee flexion (mean±SD: from 64.9±18.86 to 72.75±20.04 degrees), peak knee velocity (from 142.97±71.3 to 276.87±126.38 deg/s), peak hip velocity (from 155.01±58.41 to 162.12±53.89 deg/s), and step length (125.79±38.82 to 179.36±51.71 mm). In contrast, subjects 1 and 2 reduced these variables from Time 1 to Time 2 although they increased step frequency.

Conclusions: The preliminary results showed the high variability of joint biomechanics during the early phase of the treadmill training, as the infants with DS began to learn the new stepping skills on a treadmill. Different developmental trajectories in infants with DS support the developmental cascade framework as the goal is to achieve alternating stepping and walking independently for all infants with DS.

Author(s) Disclosures: No authors have any conflicts of interest to declare.