Aim: A low physical activity leads to obesity and a decline in the physical function. The aim of this cross-sectional study was to examine whether the association between a low physical activity and low physical function was mediated by obesity.
Methods: A total of 73 community-dwelling elderly people participated in this study. The analysis included 56 participants without knee and hip osteoarthritis, low cognitive function (the Mini Mental State Examination score <24) and rheumatoid arthritis (mean age±SD: 73.3±4.1, female: 50%). The daily step count was collected as a measure of physical activity by a single axial accelerometer. The physical function was measured by the gait speed. Obesity was measured by the body mass index and waist circumference. To assess whether the association between the physical activity and physical function was mediated by obesity, linear regression models were fitted according to Baron and Kenny procedures for a mediation analysis. A p value <0.05 was considered to be statistically significant.
Results: The body mass index did not act as a mediator in the association between the physical activity and gait speed, whereas the waist circumference acted as a full mediator in the association between the physical activity and gait speed.
Conclusion: An increased waist circumference mediates the association between a low physical activity and a low physical function in community-dwelling elderly people.