Many epidemiological studies have looked at various biomarkers to see how they are related to health. Perhaps the most familiar biomarker is total cholesterol level – although the doctors got that one wrong, since higher cholesterol is associated with lower total mortality in men, as can be seen in the following chart:
But the fact is, cholesterol isn’t a great predictor of mortality. So what is?
It turns out that exercise capacity is one of the best, if not the best, predictors of mortality in men. The higher your exercise capacity, the longer you’ll live. This is very good news, because you can always modify, that is, increase, your exercise capacity.
A meta-analysis that was published in the Journal of the American Medical Association looked at the relation between cardiorespiratory fitness and total and cardiovascular mortality. Cardiorespiratory fitness (CRF) was classified according to maximal aerobic capacity and measured as metabolic equivalent units.
Metabolic equivalent units, or METs, are a measure of exercise capacity. One MET is the amount of energy expended sitting quietly. (The precise definition is of course more technical.) Jumping rope comes in at around 11 METS. The people in the study were classified as to number of METs they were capable of in an exercise stress test, meaning maximal capacity.
Those with low CRF had a 70% greater chance of dying at any given age than did those with high CRF.
Another recent study wanted to discover what helped men and women live to old age, from the starting age of 75, to the age of 90 to be precise: How to live until 90 – Factors predicting survival in 75-year-olds from the general population. This study found that in men (but not in women), exercise capacity was the single largest factor in predicting survival from the age of 75 to the age of 90.
We report multiple factors that, both individually and jointly, predict survival until 90 years of age among 75 year-old community-dwelling residents from a defined geographical area. The most interesting finding, especially among men, was the strong association between survival and results from the exercise test, including high exercise capacity as measured by MET, high HRR after 4 minutes recovery, and high systolic BP rise during exercise. The prognostic importance of these factors greatly exceeded that of common prevalent diseases such as diabetes, hypertension, asthma, and angina pectoris/previous MI as well as that of conventional risk factors such as smoking, high BP, high level of TC, low level of HDL-c and obesity. Furthermore, both MET and HRR were significantly related to both shorter (10 year) and longer (10 to 15 year) survival.
For every one standard deviation increase in exercise capacity, the men had about a 60% lower chance of dying.
The authors don’t shy away from noting that traditional risk factors such as cholesterol seem to be far less important than exercise capacity.
The strongest predictive factor among men, exercise capacity, is clearly modifiable by physical activity, which then can improve both survival and quality of life. In contrast, traditional risk factor interventions such as the reduction of cholesterol levels and BP seem to be less important. Furthermore, exercise capacity clearly exceeds the importance of several established diseases to life expectancy. Therefore, a physically active lifestyle could compensate well for the prognostically adverse effects of such diseases. Taken together, the results of this analysis are important for preventive health care among the elderly.
The lesson here is clear: if you want to live to an old age, get moving and increase your exercise capacity.
I often get the response when I discuss extending lifespan that it’s better to live a full life without concerning oneself too much about long life. But aging means by definition more illness and disease. So if you’re only concerned about being healthy and avoiding the nursing home, you too need to exercise.