Towards Sensor-Based Mobility Assessment for Older Adults: A Multimodal Framework Integrating PoseNet Gait Dynamics and InBody Composition

The acceleration of global population aging has driven a surge in demand for health monitoring among older adults. However, traditional mobility assessment methods mostly rely on invasive measurements or laboratory-grade equipment, making it difficult to achieve continuous monitoring in daily scenarios. This study investigated the correlation between dynamic gait characteristics and static body metrics to enhance the understanding of elderly mobility and overall health. A sensor-based framework was implemented, which utilizes the <i>Short Physical Performance Battery (SPPB)</i>, combined with <i>PoseNet</i> (a vision-based sensor) for dynamic gait analysis, and the <i>InBody</i> bioelectrical impedance device for static body composition assessment. Key variables comprised the dynamic metric <i>mean directional shift</i> and static metrics, including <i>skeletal muscle index (SMI)</i>, <i>skeletal muscle mass (SMM)</i>, <i>body fat percentage (PBF)</i>, <i>visceral fat area (VFA)</i>, and <i>intracellular water</i>. Nineteen elderly participants aged 60-89 years underwent assessments; among them, 16 were males (84.21%), and 3 were females (15.79%), 50% were in the 80-89 age group, 95% did not live alone, and 90% were married. Dynamic gait data were analyzed for center displacement and horizontal directional shifts. A Pearson correlation analysis revealed that the mean directional shift positively correlated with <i>SMI</i> (ρ=0.561, p<0.01), <i>SMM</i> (ρ=0.496, p<0.01), and <i>intracellular water</i> (ρ=0.497, p<0.01), highlighting the role of muscle strength in movement adaptability. Conversely, negative correlations were found with <i>PBF</i> (ρ=-0.256) and <i>VFA</i> (ρ=-0.342, p<0.05), suggesting that greater fat mass impedes dynamic mobility. This multimodal integration of dynamic movement patterns and static physiological metrics may enhance health monitoring comprehensiveness, particularly for early sarcopenia risk detection. The findings demonstrate the framework's potential, indicating mean directional shift as a valuable dynamic health indicator.