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. Significance: A personalized exercise program to promote increased physical activity should be provided for older adults who report mobility difficulties. Future research is needed to examine causality between physical activity and mobility limitations.