Contributions of fitness and physical activity to reducing mortality.

Source

Department of Family Medicine and Community Health, University of Minnesota, Minneapolis, Minnesota.

Abstract

OBJECTIVE:

: To investigate the combined and relative contributions of physical activity (PA) and cardiorespiratory fitness (CRF) to reductions in risk of all-cause mortality in men and women.

DESIGN:

: Cohort study.

SETTING:

: Preventative health clinic (Cooper Institute).

PARTICIPANTS:

: Men and women (20-82 years) who received preventive medical examinations during 1978-2002 were eligible. Persons who were relatively healthy (defined as having no history or evidence of cardiovascular disease or cancer and achieving ≥85% of their age-predicted maximal heart rate on a baseline treadmill test) and who had been followed for ≥1 year were included (31 818 men and 10 555 women; >95% non-Hispanic white; largely from the upper socioeconomic strata).

ASSESSMENT OF RISK FACTORS:

: Risk factors for chronic diseases were evaluated at the baseline clinical examination and from medical history questionnaires. Physical activity was assessed as self-reported leisure-time or recreational activity during the previous 3 months. Frequency, duration, and intensity of activities were used to calculate total metabolic equivalent minutes per week (MET min/wk) of PA, with a cut point of 500 MET min/wk (similar to PA recommendations). Fitness was measured by the total duration of a maximal treadmill test. Low fitness included the 20% of the cohort who achieved the shortest age- and sex-adjusted treadmill time.

MAIN OUTCOME MEASURES:

: The main outcome measures were the associations of PA and CRF, separately and in combination, with all-cause mortality. Mortality data to the end of 2003 were obtained from the National Death Index. Mean follow-up time was 14.6 years for men and 12.8 years for women.

MAIN RESULTS:

: There were 1492 (469 per 10 000) and 230 (218 per 10 000) deaths in men and women, respectively. Physical activity and CRF were positively correlated in men (r = 0.49) and women (r = 0.47) controlling for age. In multivariable Cox regression analysis, PA of >500 MET min/wk was not a significant modifier of relative risk (RR) for mortality among either men (RR, 0.90; 95% confidence interval [CI], 0.80-1.01) or women (RR, 0.85; 95% CI, 0.62-1.16). Moderate or high CRF was inversely associated with all-cause mortality in men and women, both before adjustment for PA (RR for men: 0.62; 95% CI, 0.54-0.71; RR for women: 0.60; 95% CI, 0.44-0.83) and after adjustment for PA (RR for men: 0.62; 95% CI, 0.54-0.72; RR for women: 0.62; 95% CI, 0.44-0.86). In analysis stratified by PA and CRF, PA was not associated with mortality among either fit or unfit men or women. High CRF was inversely associated with mortality among men and women who did not meet the PA recommendation (RR for men: 0.61; 95% CI, 0.53-0.71; RR for women: 0.63; 95% CI, 0.45-0.89) but not significantly among those who did meet the PA recommendation (RR for men: 0.64; 95% CI, 0.39-1.04; RR for women: 0.49; 95% CI, 0.16-1.46). Assessment of the combined benefit of PA and CRF found that recommended PA (≥500 MET min/wk) contributed little to mortality risk reduction in fit men or women (eg, for women, if fit and not meeting recommended PA: RR, 0.61; 95% CI, 0.44-0.86; if fit and meeting recommended PA: RR, 0.56; 95% CI, 0.37-0.85.

CONCLUSIONS:

: Cardiorespiratory fitness contributed more to reducing all-cause mortality among generally healthy persons than the recommended level of leisure-time PA.

TimAllenMDJD

Wednesday, June 27, 2012

From U Minnesota: Contributions of fitness and physical activity to reducing mortality