Gait markers of age-associated differences in motor function in middle-aged adults: a cross-sectional study

Age-associated differences in motor function have been reported in older populations; however, variations in gait markers across different age groups in middle-aged adults remain insufficiently characterized.Clarifying these differences is essential for accurate motor assessment and targeted fall prevention in adults. This study aims to analyze the gait markers across age groups to identify candidate parameters associated with age-related differences in motor function. This study adopted a cross-sectional design and employed a digital intelligent gait stability monitoring system to perform three-dimensional dynamic imaging analysis of gait. Extracted parameters included spatiotemporal indices (step length-to-height ratio, step difference value, walking cadence, step length, walking speed, and bilateral swing and stance phases), joint kinematics (hip, knee, and ankle range of motion and angular velocity), and postural control parameters (trunk sway amplitude and mean trunk motion). Linear regression was applied to examine the associations between age and gait parameters. The primary outcome was to characterize the spatiotemporal parameters of gait, specifically step length and walking cadence, in relation to joint kinematics. Secondary outcomes were to examine the angular velocity profiles of the lower limb joints, including the hip, knee, and ankle. Among 203 participants (30–39 years: n = 86; 40–49 years: n = 63; 50–59 years: n = 54), those aged 50–59 years had significantly higher hip (β = 2.71, p < 0.001) and knee angular velocities (β = 3.30, p < 0.01), along with increased cadence (β = 6.66 steps/min, p < 0.001) compared with the 30–39-year group. Trunk sway amplitude was elevated in the 40–49 (β = 0.46, p < 0.001) and 50–59-year groups (β = 0.60, p < 0.001), accompanied by similar increases in mean trunk motion. In this middle-aged cohort, older groups showed higher hip and knee angular velocities and greater trunk sway amplitude compared with the youngest group. These parameters represent candidate markers that warrant further investigation in longitudinal studies to determine their utility for assessing age-associated motor changes. The study was registered in the Chinese Clinical Trial Registry ( https://www.chictr.org.cn ) (Registration No. ChiCTR2500112059; first registered on 14 October 2025) and approved on 10 November 2025.