Smartphone-Based Analysis for Early Detection of Aging Impact on Gait and Stair Negotiation: A Cross-Sectional Study

Abstract

Aging is associated with gradual mobility decline, often undetected until it affects daily life. This study investigates the potential of smartphone-based accelerometry to detect early age-related changes in gait and stair performance in middle-aged adults. Eighty-eight healthy participants were divided into four age groups: young (20-35 years), early middle-aged (45-54 years), late middle-aged (55-65 years), and older adults (65-80 years). They completed single-task, cognitive, and physical dual-task gait assessments and stair negotiation tests. While single-task walking did not reveal early changes, cognitive dual-task cost (DTC) of stride time variability deteriorated in late middle age. A strong indicator of early mobility changes was movement similarity, measured using dynamic time warping (DTW), which declined from early middle age for both cognitive DTC and stair negotiation. These findings highlight the potential of smartphone-based assessments, particularly movement similarity, to detect subtle mobility changes in midlife, allowing for targeted interventions to promote healthy aging.

Keywords: aging; gait; middle-age; mobility; smartphone-accelerometry; stairs.

Figure 1

The smartphone location and the measurement environments. (a) Participant walking with a smartphone attached to the lower back via an elastic belt for motion data collection. (b) Schematic of the circular corridor used for gait assessment under single and dual-task conditions. (c) Staircase (13 steps; 16 cm height, 30 cm depth, 155 cm width) used for ascent and descent evaluation at a self-selected pace.

Figure 2

Distribution of cognitive DTC (%) for gait velocity, variability, and similarity across age groups. Notes: DTC = dual-task cost. (a) cognitive DTC of gait velocity (%); (b) cognitive DTC of stride time variability (%); (c) cognitive DTC of DTW (%). The violin diagram shows the distribution of the groups: green for young adults, orange for early middle-aged, blue for late middle-aged, and purple for older adults. The box within the violin represents the interquartile range (IQR), with the center line indicating the median.

Figure 3

Age-related effects on stair ascent and descent: distributions of duration and movement similarity. Notes: DTW = Dynamic time warping. (a) Stair ascending total time (s); (b) DTW during stair ascent; (c) stair descending total time (in seconds); (d) DTW values during stair descent. The violin diagram shows the distribution of the groups: green for young adults, orange for early middle-aged, blue for late middle-aged, and purple for older adults. The box within the violin represents the interquartile range (IQR), with the center line indicating the median. Asterisks (*) indicate p < 0.001 compared to the young adult group, and plus signs (+) indicate p < 0.001 compared to the middle-aged group.