Association Between Accelerometer-Measured Physical Activity and Mobility Limitations in Twins

Background: The associations between mobility limitations and device-measured physical activity are sparsely studied. In this study, these associations are studied among community-dwelling older twins. Methods: This cross-sectional study utilized data gathered in 2014-2016 for the MOBILETWIN study. Participants were twins born in Finland between 1940 and 1944 (774 participants, mean age 73 years). Physical activity was measured with a hip-worn accelerometer. Mobility limitations were assessed with a questionnaire. Results: Individual-level analyses revealed that physical activity was associated with mobility limitations. Participants with severe mobility limitations took 2,637 (SD = 1,747) steps per day, those with some mobility limitations 4,437 (SD = 2,637) steps, and those without mobility limitations 7,074 (SD = 2,931) steps (p < .05). The within-twin pair analyses revealed the same pattern for the 144 dizygotic twin pairs, but no associations were seen for the 117 monozygotic twin pairs. Conclusions: Accelerometer-measured physical activity and mobility limitations were associated in community-dwelling older adults. Genetic factors may explain some of the variations in physical activity.