How much exercise will increase your lifespan?

It doesn't say anything about the answer to the question. Lots of blather but nothing objective. 

How much exercise will increase your lifespan?

Naveed Saleh, MD, MS, for MDLinx | March 27, 2019

People with elite-performance cardiorespiratory fitness had an 80% lower mortality risk compared with people with low cardiorespiratory fitness, according to the results of a high-powered study published in JAMA Network Open.

The greater your cardiorespiratory fitness level, the lower your risk of mortality, according to researchers.

On the other hand, “[t]he increase in all-cause mortality associated with reduced cardiorespiratory fitness was comparable to or greater than traditional clinical risk factors,” such as coronary artery disease, smoking, and diabetes, wrote the study authors, led by cardiologist Kyle Mandsager, MD, Cleveland Clinic Foundation, Cleveland, OH. “Importantly, there was no upper limit of benefit of increased aerobic fitness.”
This retrospective study included the largest reported treatment group of adult patients referred for exercise treadmill training at a tertiary care center (N=122,007; average age: 53.4 years; median follow-up: 8.4 years).
Results from exercise treadmill testing were age- and sex-matched into the following fitness groups: low (< 25th percentile), below average (25th to 49th percentile), above average (50th to 74th percentile), high (75th to 97.6th percentile), and elite (≥ 97.7th percentile).

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In total, 13,637 patients died during 1.1 million person-years of observation. The risk-adjusted all-cause mortality was inversely proportional to cardiorespiratory fitness, and was lowest among elite performers. Mortality benefits were observed with every subsequent performance group in a dose-dependent manner. In other words, any incremental increase in cardiorespiratory function resulted in improvement to mortality.
“Extreme cardiorespiratory fitness (≥2 SDs above the mean for age and sex) was associated with the lowest risk-adjusted all-cause mortality compared with all other performance groups,” the authors reported.
Upon subgroup analysis, the survival benefit of elite vs high performers was most notable in patients older than age 70. In this age group, elite performers had a nearly 30% reduced risk of mortality compared with high performers. In younger age groups, no statistical difference in outcomes was evident between elite and high performers.
For patients with hypertension, the elite performers again showed a 30% reduction in all-cause mortality compared with high performers.

U-shaped dose-response curve?

The negative association between cardiorespiratory fitness and mortality has been previously demonstrated in the literature. This phenomenon was shown to be independent of race, age, sex, and comorbidities. Moreover, heightened cardiorespiratory fitness has been significantly linked to decreased prevalence rates of coronary artery disease, hypertension, diabetes, cancer, and stroke.
Recent results from observational studies, however, undermine the logic that daily rigorous exercise may prolong life in patients. Specifically, the hemodynamic stress of such regular intense exercise can yield cardiovascular changes, such as increases in cardiac chamber volumes, a balanced increase in left ventricular mass, and changes in autonomic tone. These physiologic changes could lead to atrial fibrillation, aortic dilation, coronary artery calcification, and myocardial fibrosis.
“These findings have led some to propose a U-shaped dose-response association between exercise and cardiovascular events,” wrote the authors. “It remains unclear whether these associations are signals of true pathologic findings or rather benign features of cardiovascular adaptation.”

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This study was the first to evaluate the relationship between extreme cardiorespiratory fitness and mortality. The authors suggested that discrepancies between their findings and previous population-based studies could be due to biases in population-based studies, with subjects self-reporting activity levels as well as other variables unaccounted for, including genetic factors and unmeasured health habits.
One limitation of the current study is that it assigned performance levels based on only one exercise treadmill training test; subjects could very well change exercise habits during the multiyear follow-up period.
“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,” concluded the researchers.