Research supports the premise that regardless of age, sex, race, and comorbidities (simultaneous presence of two or more diseases or conditions), there is an inverse relationship between cardiorespiratory fitness (CRF) and mortality.
By the same token, CRF has also been associated with a higher quality of healthy life – owning to reductions in the risk to coronary artery disease, high blood pressure, diabetes, stroke, and cancer.
According to research – Association of Cardiorespiratory Fitness with Long-term Mortality Among Adults Undergoing Exercise Treadmill Testing – which appears on JAMA Network Open Cardiology in October 2018, “newer evidence has suggested associations between habitual vigorous exercise and potentially pathologic cardiovascular findings, including atrial fibrillation, coronary artery calcification, myocardial fibrosis, and aortic dilation.”
As a result, researchers from the Cleveland Clinic Foundation, Cleveland, Ohio, chose to assess, “the association between aerobic fitness and all-cause mortality among the largest reported cohort, to our knowledge, of adult patients undergoing ETT (exercise treadmill testing) at a tertiary care center,” in a retrospective study. The Cleveland researchers point out that ETT, “is the most widely used method to measure CRF, and serves as an objective measure of aerobic fitness and moderate-vigorous physical activity, without reliance on self-reported data.”
The study population included consecutive adult patients undergoing stress testing at the Cleveland Clinic from January 1st 1991 through December 31st 2014. At the time of stress testing patient age, sex, height, weight, body mass index, medications, and comorbidities were recorded.
Performance stratification used data obtained during the ETT. “The CRF was quantified as peak estimated METs (measure of metabolism) and was determined based on treadmill grade and speed at peak exercise.
In addition, all-cause mortality information was obtained from the Social Security Death Index, when available – along with medical records of a patient’s death, using the institutional death index.
The conclusions included, “findings (that) emphasize the importance of aerobic fitness in overall health, including the magnitude of benefit of increased CRF in relation to traditional clinical risk factors and the incremental survival advantage of extremely high fitness.” And, “overall, increases in CRF were associated with a reduction in all-cause mortality at any level, without evidence of a plateau effect.”
A very important finding was that, “there does not appear to be an upper limit of aerobic fitness above which a survival benefit is no longer observed.” It was also observed that benefits of “extremely high fitness” may be reduced in individuals suffering with coronary artery disease or certain cardiac risk factors.
The Cleveland researchers concluded by commenting that, “cardiorespiratory fitness is a modifiable indicator of long-term mortality, and health care professionals should encourage patients to achieve and maintain high levels of fitness.”