Cohort effects in physical inactivity A neglected category and its health economical implications

Marked age-dependent physical inactivity is generally assumed in the health science literature. On the basis of cross-sectional studies it is assumed that the probable physical inactivity increases linearly with increasing age. Health economical analyses based on this assumption result automatically in the conclusion that an aging society and the associated increasing inactivity will lead to higher health-care costs. The object of this paper was to check the validity of this underlying assumption. The data records of the German Socio-Economic Panel Study (GSOEP) for the years 1985-2001 served as a basis. With the aid of longitudinal and cohort sequence analyses, it was shown that not only the effects of age, but also those of period and cohort effects always influence health behaviour. The effects of age can be absolutely compensated for, or in part even overcompensated, by the period and cohort effects. For this reason, the aging of society itself does not necessarily lead to higher health-care costs owing to certain parameters of health behaviour, even if cross-sectional studies show an increasing incidence with age.