The Effect of Physical Activity and Cardiorespiratory Fitness on All-Cause Mortality in Hong Kong Chinese Older Adults.

BACKGROUND

It is unclear whether physical activity (PA) could predict all-cause mortality independently of cardiorespiratory fitness, and there are relatively few studies evaluating the combined effect of PA and cardiorespiratory fitness on mortality.

METHODS

We invited 1,242 Chinese older adults aged 69-94 years from the MrOs and MsOs cohort (Hong Kong) study for a 7-year follow-up. PA was measured by the Physical Activity Scale of the Elderly (PASE). Cardiorespiratory fitness, expressed as maximal oxygen uptake (VO2max), was assessed by performing symptom-limited maximal exercise testing on an electrically braked bicycle ergometer and 6-m walk test. We aimed to examine the independent and combined effect of PA and VO2max with all-cause mortality by cox proportional hazards models.

RESULTS

Ninety-nine deaths occurred over a mean follow-up of 5.3 ± 0.8 years. PA was inversely associated with all-cause mortality in unadjusted and fully-adjusted models, and the association was still significant after further adjusted for VO2max. In stratified analysis, PA was significantly related to all-cause mortality within both unfit and fit strata. As compared with those being active and fit, physically inactive and cardiorespiratory unfit individuals had the highest all-cause mortality risk. Physically active but unfit individuals and inactive but fit individuals had similar all-cause mortality risk.

CONCLUSIONS

Among older adults, PA was an important predictor of all-cause mortality independently of VO2max. High cardiorespiratory fitness does not necessarily confer low mortality risk in physically inactive older adults.