Sitting around all day and not exercising can result in a risk of death that is three times higher than for smoking, a new study shows.
Conversely, being extremely fit reduced your risk of death by 80 per cent compared to modestly fit people.
The study is another powerful reinforcement of many recent findings that have established that moderate to vigorous exercise, such as regular bike riding, has powerful health benefits.
Interestingly, that is not what the researchers set out to find.
The group at the University of Cleveland was seeking to establish whether it was true, as some reports have suggested, that extreme exercise could be bad for the heart.
But they found the opposite: vigorous exercise is highly beneficial, and the more the better.
The researchers retrospectively studied 122,007 patients who underwent exercise treadmill testing at Cleveland Clinic from 1991 to 2014, to measure all-cause mortality relating to the benefits of exercise and fitness.
The study found that increased cardiorespiratory fitness was directly associated with reduced long-term mortality, with no limit on the positive effects of aerobic fitness.
Extreme aerobic fitness was associated with the greatest benefit, particularly in older patients (70 and older) and in those with hypertension.
"Aerobic fitness is something that most patients can control. And we found in our study there is no limit to how much exercise is too much," said Wael Jaber, M.D., Cleveland Clinic cardiologist and senior author of the study. "Everyone should be encouraged to achieve and maintain high fitness levels."
The risk associated with poor cardiorespiratory fitness was comparable to or even exceeded that of traditional clinical risk factors, such as cardiovascular disease, diabetes and smoking.
The study's findings emphasize the long-term benefits of exercise and fitness, even to extreme levels, regardless of age or coexistent cardiovascular disease.
The study found that extreme fitness provided additional survival benefit over more modest levels of fitness, and that extremely fit patients lived the longest.
"Extreme aerobic fitness was associated with the greatest survival and was notably beneficial in older patients and those with hypertension.
"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", the report concluded.