Mechanical energy exchange during plane walking and stepping over obstacle in subjects with Down syndrome

The purpose of this study is to compare mechanical energy exchange, and mechanical work and power generated or absorbed at the lower limbs joints in young adults with Down syndrome (DS) (21.6±7 years) with an age-matched control group of healthy subjects (CG, N) (25.1±2.4 years). The subjects walked along a walkway in two conditions: plane walking, and stepping over an obstacle (10% of the subject’s height). The tasks were acquired using an optoelectronic system for quantitative movement analysis. Also ground reaction forces were sampled from two force plates mounted in the middle of the walkway. Spatiotemporal, mechanical energy, and joints’ power and work parameters have been obtained and analyzed respectively with Smart Analyzer (Elit2002, BTS) and proper statistical software. Spatiotemporal parameters demonstrated a different motor strategy in DS compared to N in both conditions. DS walked slower, with shorter step length, and greater step width in both conditions. While potential energy exchanges were similar between groups, kinetic energy was lower in DS compared to N in both conditions. However, according to the literature, DS, compared to N used different motor strategies; they had similar values of mechanical energy recovery (ER) in all conditions. It means that DS can recover almost the same percentage of consumed mechanical energy with N during a gait cycle. Also, results showed that powers generated or absorbed in lower limbs joints and work produced in these joints were different across groups.