How important is exercise for health?
We all know that exercise is good for us. But just how good, and how much exercise do we need to be healthy? Exercise capacity powerfully predicts survival.
A just-published study in Heart quantifies the healthfulness of exercise in terms of reduction of the death rate, and compares it to chronological age as a predictor of mortality and survival.(1)
The study looked at over 57,000 people, median age 53, who had performed treadmill stress tests, which test exercise capacity. It then followed them for ~10 years for all-cause mortality, and ~5 years for myocardial infarction (heart attack).
Biological age, as determined by exercise capacity, varied widely, up to three decades within each decile of chronological age.
In other words, one person who was 50 years old and had a high exercise capacity might show a biological age of 35, another with low exercise capacity a biological age of 65.
The study found:
Higher exercise capacity was strongly associated with greater survival, with per-MET HR ranging from 0.82 in patients under 40 years of age, to 0.88 in those over 70 years of age. Biologic age varied markedly—up to three decades—within each age decile, and was a stronger predictor of mortality and MI than chronologic age.
Metabolic equivalent units: what they are and why they’re important
METs are metabolic equivalent units, a measure of exercise capacity. One MET is equivalent to the amount of energy expended by sitting quietly. The following table shows some sample activities and how they relate to METs.
According to the study, each incremental MET of exercise capacity was associated with an 18% reduction in risk of death in those under 40, and a 12% reduction in those over 70.
Presumably just about everyone could perform activities at about 2 METs, “walking, level ground, strolling, very slow”. So compared to that person, someone who can vigorously jump rope would have a much lower risk of death, a small fraction of the risk compared to a sedentary person.
Another example would be a person who could perform vigorous calisthenics at a MET of 8.0, vs someone who can perform jogging, at a MET of 7.0. If under age 40, the one doing calisthenics has a risk of death 18% less than the jogger; if over 70, the risk is 12% less.
Note that exercise intensity is key, which is one reason that high-intensity training is so effective and better for health than aerobics.
This study confirms the results of another study that I wrote about: How to live until 90. It’s worth repeating a sentence from that previous study:
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.
Exercise capacity as a factor in survival to old age was much more important than cholesterol, blood pressure or even a previous heart attack.
How to live until age 90
Here’s a chart that shows the survival curves for men (left side) based on low vs high exercise capacity between the ages of 75 and 90. By age 90, twice the number of men with high exercise capacity were alive compared to those with low. Since this was a simple dichotomy, high vs low, I would expect to see even more dramatic results in men who have a top level capacity for exercise.
Exercise capacity appears to be the single strongest predictor of survival, better than cholesterol, HDL, blood pressure, diabetes, or even angina pectoris (chest pain).
If you don’t exercise, you deteriorate.