Age-Related Differences in Joint Kinematics and Spatiotemporal Parameters During Ramp Walking and Level Walking: Cross-Sectional Study.

Background: Gait function is essential for mobility and independence in older adults. Although age-related gait decline on level walking has been studied extensively, there is less information on how aging affects gait during ramp walking, despite its relevance in daily life. Different biomechanical strategies are used during ramp ascent and descent; however, detailed joint kinematics remain unclear, particularly under real-world conditions. Objective: This study aims to investigate age-related differences in lower-limb joint angles and spatiotemporal parameters between level and ramp walking. Methods: Gait was assessed in 20 young (mean 31.3, SD 8.9 y) and 20 older (mean 64.2, SD 0.8 y) healthy adults using a markerless motion-capture system (Theia3D) in a living laboratory setting. Participants completed gait trials during level walking and on a 7° ramp (ascent and descent). Between-group comparisons of spatiotemporal parameters were performed using independent 2-tailed t tests, while joint angle data were analyzed using a linear mixed model with walking velocity as a covariate. Estimated marginal means were compared across age groups within each walking condition, and all P values were adjusted using the false discovery rate method. Effect sizes were calculated using Cohen d to examine whether between-group differences were more pronounced during ramp walking compared to level walking. Results: Ramp walking revealed multijoint kinematic alterations, while level walking showed limited differences (hip flexion and knee extension angles only). During ramp ascent, significant increases in knee flexion angle and reductions in ankle plantarflexion angle were observed. During ramp descent, multijoint changes were evident, including increased hip flexion and reduced knee extension and ankle plantarflexion angles. Effect sizes were particularly large during ramp walking (eg, knee flexion during ascent: |d|=2.37; knee extension during descent: |d|=1.87), while level walking showed large effect sizes for several parameters (eg, knee MaxExtStance: |d|=1.18; hip MaxFlexStance: |d|=1.17) despite reaching statistical significance for only a few parameters. Conclusions: In this cross-sectional sample, age-group differences in joint kinematics were more pronounced during ramp walking than during level walking, even after adjusting for walking velocity. This suggests that ramp walking may be a more sensitive task for detecting age-related adaptations compared to level walking. Markerless motion capture enables practical assessment in real-world settings. However, longitudinal studies are needed to determine whether these patterns predict functional decline.