To examine whether analysis of smartphone-based accelerometry during sit-to-stand tests performed on a regular chair and a cushioned sofa could be useful for detecting subtle changes in mobility in middle age.
Twenty-three young (25.0±2.5 years), 25 middle-aged (52.0±5.2 years), and 17 older adults (70.0±4.1 years) performed the 5-times sit-to-stand test on both a standard chair (height = 0.46 cm, depth = 0.45 cm) and a cushioned sofa (height = 0.40 cm, depth = 0.50 cm). A smartphone attached to the participant's lower back was used to measure lower-limb muscle power, maximal vertical velocity (MVV) during rising, the duration of the total task and the sub-phase of transition from sitting to standing (SiToSt), and repetition variability using the dynamic time warping (DTW) method.One-way analysis of variance (ANOVA) or the Kruskal-Wallis compared between age groups, with post-hoc analysis as appropriate.
Middle-aged adults exhibited reduced lower-limb muscle power compared to young adults (5.25 vs 6.19 W/kg, p=0.034), with the difference being more pronounced on the sofa (6.23 vs 8.08 W/kg, p=0.004). Differences between middle-aged and young adults in terms of MVV (0.87 vs 1.02 m/sec, p=0.011) and SiToSt duration (0.41 vs 0.33 sec, p=0.038) were only detected on the sofa, and the middle-aged adults showed less variability compared to the older adults on the chair (1.1 vs 1.63, p=0.018). In either condition, there was no difference in total task duration between the middle-aged group and the young or older adults.
Smartphone accelerometry-derived measures, such as power and maximal rising velocity, may identify subtle changes in mobility performance in middle age. Our findings may offer a simple and accessible screening tool for mobility assessment in this population.
Growing evidence highlights the importance of assessing mobility before the age of 65 to identify preclinical mobility impairments. Traditional tests such as the 5-times sit-to-stand are often not sensitive enough to detect subtle deterioration in midlife. Our findings which demonstrated the utility of a smartphone accelerometry-based sit-to-stand in identifying subtle mobility changes in midlife can enhance physiotherapists' abilities that play a critical role in the early detection of functional decline and the adaptation of interventions. Additionally, physiotherapists should explore more challenging variations, such as performing 5-times STS from a cushioned sofa, to improve midlife mobility assessment and preventive care strategies.
Midlife
Mobility
