Fifteen minutes daily physical activity may be a new best target in older adults: The proof cohort study

Abstract

Aging is associated with a decrease of the activity level of the Autonomic Nervous System (ANS). With aging, the decline in activity coincides with the occurrence of deaths. It is well established that physical activity (PA) is an efficient strategy for successful aging. This work focuses on the regulation of the ANS by PA and their close relationship in the prevention of cardiovascular events. The PROOF (PROgnostic indicator OF cardiovascular and cerebrovascular events) cohort study was designed in 2001 to prospectively assess the predictive value of ANS activity level among a healthy retired French population. PA was assessed every 4 years with self-administered questionnaires and was measured in Metabolic Equivalent of Task (MET)-minutes. We looked at the associated risk of mortality for four categories of weekly PA in MET-minutes, defined as inactive (< 1 MET-min/wk), low (1–499 MET-min/wk), medium (500–999 MET-min/wk) or high (≥ 1000 MET-min/wk). ECG recording were performed every 4 years and SDNN (standard deviation of RR intervals) reflected the regulation of the heart rate by the ANS. Out of the 1011 65-year-old subjects initially included in 2001, the 15 years of follow-up has been currently completed for 688 (68%) subjects, and 89 (9%) deaths were reported. The relative risk of death (all causes) was reduced by 22% (RR = 0.78 [95% CI: 0.25–0.90], P < 0.05) for subjects achieving a low dose of PA compared with an inactive lifestyle. For active subjects even for a low dose of PA, SDNN was stable compared with inactive subjects during the follow-up. Our data from the PROOF cohort suggest that the positive effects of a low dose of PA could thus be, at least partially, explained by its protective impact on ANS activity. ANS up-regulation by the low dose of PA might thus be key for a successful aging.