Abstract

Introduction Both elevated levels of physical activity (PA) and high cardiorespiratory fitness (CRF) are associated with a decreased risk of all-cause mortality. The degree to which an individual's PA level and CRF status interact to influence mortality is not currently fully understood. This study investigated whether PA and CRF were independently related to all-cause mortality, and to what degree PA was associated with improved mortality risk in individuals with low CRF. Methods This is a prospective cohort study using health assessments on individuals gathered between 1975 and 2002. Health assessment data were matched with the National Death Registry to assess all-cause mortality. This study employed a self-reported measure of PA and Bruce protocol maximal treadmill to estimate CRF. Survival analyses were conducted using Cox proportional hazards regressions. Results Of 3,829 clients who were assessed, a total of 180 clients died within the follow-up period. The mean follow-up period was 25.4 ± 7 years. CRF was significantly and strongly related to all-cause mortality in a dose response manner. PA was not significantly related to all-cause mortality under a multivariable model. Discussion The primary finding was a strong inverse, dose response relationship between CRF and risk of all-cause mortality. This relationship further strengthens a large body of evidence suggesting that CRF may be a better predictor of all-cause mortality than an individual's self-reported PA. It is hypothesized that the apparent lack of relationship here observed between PA and all-cause mortality is largely due to the lack of specificity in the measure of PA employed, as well as the inaccuracy of self-report generally. Conclusion Physicians may benefit from employing objective measures of CRF in clinical settings instead of self-report-based measures of PA for the assessment of mortality risk. When studying the relationship between PA status and mortality, a more specific measure of PA than minutes of moderate to vigorous PA per week may be required. Further research should investigate the way in which PA is related to mortality in individuals with low CRF.

Degree

College and Department

Life Sciences; Exercise Sciences

Rights

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