Walking Parameters of Older Adults on Hilly and Level Terrain Outdoors.

Background/objective: To understand how older adults adapt their walking to various environments, it is important to study walking outdoors, including on hilly terrain. This cross-sectional study aimed to validate inertial measurement units (IMUs) for detecting older adults' walking parameters on uphill and downhill terrains and to compare these parameters between level and hilly terrains.

Methods: A sample of older adults (N = 35; Mage = 76 years, SD = 5; 71% women) walked on a level, uphill, and downhill route outdoors at self-selected speeds. Three IMUs were used to estimate walking parameters (step, stride, swing, and stance durations; cadence; step length; and walking speed). IMUs were validated against high-speed video camera data from six participants. After validation, differences in walking parameters between the three terrains were assessed with repeated measures analysis of variance and variability of the parameters (SD/mean × 100%) with Friedman's test.

Results: IMUs showed mainly good to excellent validity for temporal but not spatial walking parameters in hilly outdoor environments. Older adults exhibited longer step, stride, and swing durations, and lower cadence on level and uphill versus downhill. On level terrain, cadence was higher, and step, stride, and stance durations were shorter than uphill. Variability of temporal parameters was greatest uphill.

Conclusion: IMUs demonstrated potential to measure walking parameters of older adults in hilly terrain. The results suggest that older adults' outdoor walking parameters differ between level and hilly terrain. Significance/Implications: These results can inform the design of outdoor walking interventions for older adults by considering the usability of IMUs and the changes in walking parameters due to environment.