Daily-Life Walking Characteristics of Older Adults in Relation to Age, Sex, and Physical Function: the HUNT4 Trondheim 70+ Observational Study.

Background: Knowledge about how older adults walk is crucial for the effective prevention and treatment of various mobility issues as well as treatment evaluation, but it is currently largely limited to laboratory-based measurements. Although laboratory-based data provide relevant information about what older adults can do under standardized conditions, they do not provide insight into how they actually walk in their daily life, a gap that needs to be addressed urgently. Objective: The objective of this study was to describe how older adults walk in daily life, in relation to age, sex, and level of physical function, using wearable sensor data from a large sample of older adults with a wide range of age and function from the HUNT4 Trondheim 70+ study. Methods: The current study is based on 1-week accelerometer data (Axivity AX3) from 1289 older adults (mean age 77.41, SD 6.06 years; age range 70-105 years; n=705, 54.7% women). Physical function was assessed using the Short Physical Performance Battery (SPPB). To investigate the effect of age and SPPB score on gait metrics (daily number of steps, 95th percentile speed, mode speed, 95th percentile cadence, mode cadence, and maximum walking bout [WB] distance) for women and men, univariate gamma regression models with log link were used for each outcome measure, with age and SPPB score in separate models. Sex differences were investigated using Mann-Whitney U tests. Results: Older adults showed a large variation in how and how much they walked in daily life across age, sex, and physical function, particularly younger participants and those with better physical function. Most gait metrics decreased at an increasing rate with higher age, with men maintaining their levels up to higher ages than women. Poorer physical function led to an exponential or close-to-linear decrease in all gait metrics apart from habitual cadence, which remained stable up to a high age. Women had a lower daily number of steps, gait speed, and maximum distance but higher cadence than men (P<.001 for all). On average, 63% of all WBs lasted <10 seconds, corresponding to a median accumulated time of 99 (IQR 66-128) minutes. For WBs lasting 10 to 30 seconds, 30 to 60 seconds, and >60 seconds, the median accumulated time was 105 (IQR 65-154) minutes, 31 (IQR 18-47) minutes, and 113 (IQR 37-219) minutes, respectively. Conclusions: Daily-life walking performance was affected more by functional ability than by age itself, except for the highest ages, and differed significantly between sexes. Although most WBs were very short, the total accumulated walking time in WBs shorter than 30 seconds was longer than that in longer WBs. Future research can build upon our findings by considering both the impact of short WBs and relevant group and sex differences when implementing daily-life mobility assessment in both clinical studies and patient follow-up.