Midlife Cardiorespiratory Fitness and Long-Term Mortality Risk
What is the association between cardiorespiratory fitness (CRF) and mortality in middle-aged men without known cardiovascular disease (CVD)?
The study population came from the Copenhagen Male study, which prospectively enrolled working men 40-59 years of age in 1970-71. Participants filled out a questionnaire, including questions on physical activity, and underwent a history and physical examination. Intake CRF was assessed by bicycle ergometer and Astrand’s normogram (Astrand PO, Ryhming I. J Appl Physiol 1954;7:218-21). A total of 5,107 formed the final cohort. The Danish Central Person Register and Danish Register of Causes of Death (death certificates) were used to determine all-cause mortality and cardiovascular mortality. Four categories of age-adjusted CRF levels were defined: 45% of participants in “low normal (LN),” 45% in “high normal (HN),” the lowest 5% “below lower limit of normal,” and the highest 5% “above upper limit of normal.” Multivariable and regression modeling were applied.
Over the 46 years of follow-up, 2,149 (42.1%) men died of CVD. Higher CRF was associated with significantly lower prevalence of hypertension, lower body mass index, higher self-reported activity, lower alcohol intake, and higher smoking rate. After multivariable adjustment, compared to the below lower limit of normal group, LN CRF was associated with a 2.1-year increased life expectancy; HN CRF with a 2.9-year increase; and above upper limit of normal with a 4.9-year increase. CRF was inversely associated with CV mortality incidence. When all men who died within the first 10 years of follow-up were excluded, the significant association between CRF and longevity was maintained.
CRF in a dose-dependent manner was significantly associated with increased life expectancy over 46 years of follow-up in middle-aged men without known CVD at the time of enrollment.
- Strengths: Over four decades of follow-up, over 5,000 subjects, both self-reported and objective assessments of physical activity.
- Limitations: Entirely male cohort, no data on influence of change in level of CRF over time, VO2 testing has evolved since the start of the study.
- Impact: This study provides additional evidence that CRF, even at LN levels, improves longevity. Physical activity or fitness should be a “vital sign” discussed routinely in the clinic.
- Of note, the rate of all-cause mortality incidence was steepest in the above upper limit of normal group beyond 30 years of follow-up; 200 (78%) in this group were self-reported smokers. However, prior studies have demonstrated CV detriment from intense levels of activity (i.e., the “U shaped” curve).
Keywords: Alcohol Drinking, Body Mass Index, Exercise, Exercise Test, Hypertension, Longevity, Middle Aged, Physical Fitness, Primary Prevention, Smoking, Sports
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