Association between physical activity, multimorbidity, self-rated health and functional limitation in the Spanish population.
BACKGROUND
Physical activity (PA) has been shown to improve the general health of patients with chronic diseases and to prevent the onset of such conditions. However, the association between multimorbidity and PA has not been investigated in detail, and recent studies of this topic yield dissenting results. The objective of this study was to examine whether PA levels were associated with multimorbidity, self-rated health and functional limitation.


METHODS
This was a cross-sectional study based on data from the 2009 European Health Interview Survey for Spain. The sample population included 22,190 adults over 15 years of age. The independent variables were multimorbidity (measured as the number of chronic diseases), activity limitations, and self-rated health status. The dependent variable was PA level, measured as a) a continuous variable in metabolic equivalents (METs) and b) a dichotomous variable based on international recommendations (</≥500 MET-minutes per week). The associations between the dependent and independent variables were evaluated across sex and age groups (16-24, 25-44, 45-64, 65-74, >74 years), using multivariate linear and logistic regression models that were adjusted for age, educational level and employment status.


RESULTS
An inverse association was found between PA and multimorbidity among older males and young females between 16-24 years. This negative association was also observed among males aged 25-44 years when analysing PA as a dichotomous variable. Self-rated health status was directly related to the achievement of minimum PA levels among middle-aged and older individuals, but the opposite happened among the youngest group of females. Significant associations between the existence of activity limitations and the performance of lower volumes of PA were consistently observed among subjects over 44 years.


CONCLUSIONS
There is an inverse association between multimorbidity and PA in the youngest and oldest age groups. In addition, both low self-rated health status and the presence of functional limitations were related to lower PA in most of the examined population groups. These features should be considered in the design and implementation of community-based approaches to promoting PA, if further corroborated in longitudinal studies.