Perceived physical activity and mortality: Evidence from three nationally representative U.S. samples.

OBJECTIVE: This research sought to examine the relationship of individuals' perceptions about their level of physical activity with mortality outcomes at the population level.

METHOD: This study used 3 nationally representative samples with a total sample size of 61,141 U.S. adults (weighted N = 476 million). Data from the 1990 National Health Interview Survey (NHIS) and the 1999-2002/2003-2006 National Health and Nutrition Examination Survey (NHANES) were linked to prospective National Death Index mortality data through 2011, yielding follow-up periods of up to 21 years. Cox proportional hazards models were used to determine the association between respondents' perceptions of their relative level of physical activity (compared with other people their age) and all-cause mortality, adjusting for actual levels of physical activity, health status and behavior, and sociodemographic variables.

RESULTS: Perceived physical activity relative to peers was associated with mortality risk. Individuals who perceived themselves as less active than others were up to 71% more likely to die in the follow-up period than those who perceived themselves as more active. This finding held across 3 samples and after adjusting for actual levels of physical activity and other covariates.

CONCLUSIONS: Individuals' perceptions about their level of physical activity strongly predicted mortality, even after accounting for the effects of actual physical activity and other known determinants of mortality. This suggests that perceptions about health behaviors may play an important role in shaping health outcomes. (PsycINFO Database Record