Up and down: analyzing physical activity and posture with wearable sensors during partial bodyweight supported play for young children with down syndrome

Background and objective Children with Down syndrome experience delays in motor development. Open-area partial bodyweight support (PBWS) systems can help support motor development, but no study has objectively reported motor behavior changes, such as increased leg activity or time spent upright. This study quantified changes in physical activity and posture during exploratory play with a PBWS system for pre-ambulatory children with Down syndrome. We hypothesized that PBWS would increase both physical activity levels and upright posture duration.Methods This randomized, multisite crossover trial included children with Down syndrome who could sit independently but were not yet walking. Each child completed nine 30-minute play-based sessions with and without PBWS. Physical activity and posture were measured using shank-worn accelerometers, capturing the percentage of time spent in high physical activity and upright. Nonparametric Mann-Whitney U tests compared outcome measures between PBWS and non-PBWS conditions.Results Fifteen children (mean age: 19.4 months, range: 12–31 months) completed study procedures. Across all participants, high physical activity did not noticeably increase from the first to last session. The median change was −5.0% (IQR: −13.4- +9.05%) with PBWS and −2.53% (IQR: −13.7- +12.9%) without PBWS. Time spent on feet showed a median increase of +2.38% with PBWS (IQR: −0.96 – +12.24) and a decrease of −1.08% without PBWS (IQR: −7.70 - + 1.02%). A statistically significant difference between conditions (p = .042) indicated greater improvements in time on feet during PBWS sessions versus without.Discussion PBWS did not increase time spent in high physical activity, but did support increased upright posture over time. These findings suggest PBWS systems may provide a supportive environment for practicing upright postures in early motor development for children with Down syndrome. Longer interventions may be needed to evaluate the full impact of PBWS on motor development. This study adds to growing evidence supporting early, engaging, and accessible motor interventions for children with DS.Trial registration This study was registered at ClinicalTrials.gov (CT #NCT05307523).