When it comes to living longer through exercise, is more better?

Many factors -- including genetics, not smoking, quality of health care, diet and social engagement -- play an important role in successful aging, but adequate exercise helps protect against numerous age-related conditions including heart disease, sarcopenia (the loss of muscle associated with aging), cancer, obesity and loss of cognitive function.

“Even in old age, exercise and moderation can preserve something of young vigor,” Roman philosopher Marcus Tullius Cicero reported in 44 B.C. And since then, research into the important role of exercise for good health and longevity has confirmed his declaration.

Many factors — including genetics, not smoking, quality of health care, diet and social engagement — play an important role in successful aging, but adequate exercise helps protect against numerous age-related conditions including heart disease, sarcopenia (the loss of muscle associated with aging), cancer, obesity and loss of cognitive function.

Although the majority of the US population does not meet the Centers for Disease Control and Prevention’s recommended minimum weekly amounts of exercise (150 minutes of moderate activity or 75 minutes of vigorous), what about the small percentage who markedly exceed these recommendations? Do those folks live longer than the rest of us?

A comprehensive review article published this year suggests that the answer is “yes” when it comes to light to moderate physical activity (walking, golf, tennis). Those who engaged in the highest levels of this type of physical activity level lived on average 5.5 years longer than their sedentary counterparts.

Another study that looked at the exercise habits of more than 660,000 men and women found a 20% reduced risk of dying prematurely in those doing less than the CDC’s recommendations, compared with doing no exercise at all, and a 31% decreased risk of death in those performing up to twice the minimum. Researchers found an upper threshold for longevity benefit of 39% reduced risk of dying prematurely for those engaging in three to five times the weekly minimum recommendations.

The study also found no evidence of harm (but also no additional benefit) in those who exercised 10 or more times the recommended weekly minimum.

When it comes to vigorous endurance exercise, such as running marathons and ultra-marathons, competing in Ironman triathlons or doing long-distance bike races, the answer is not quite as clear.

A 2017 study found that older male endurance athletes with a low risk profile for heart disease were more likely to have a greater amount of calcium plaque in their coronary arteries (plaques are calcium deposits in the walls of the artery that can cause narrowing and stiffness) compared with sedentary men. However, more than 60% of both groups had no evidence of calcium in their arteries.

The authors of that study question the significance of this observation because plaques with calcium are more stable than non-calcified plaques and therefore less likely to cause a heart attack.

Conversely, a study of female marathon runners found that they had less evidence of coronary plaques than their sedentary counterparts. An older study found that longtime endurance athletes had about five times greater risk of the heart arrhythmia known as atrial fibrillation than sedentary individuals. And several studies have found an increase in myocardial fibrosis (scarring of the heart) in endurance athletes, but again, the significance in terms of the risk of dying prematurely is not entirely clear.

Despite these potential risks, a 2012 paper notes that “lifelong vigorous exercisers generally have low mortality rates,” and a study on former Tour de France cyclists (a race considered one of the most challenging sporting events in the world) found that they lived on average eight years longer than the general population.

A 2015 Finnish study that looked at former elite endurance athletes found them to have a five- to six-year increase in life expectancy, with a significant decrease in the risk of stroke and heart disease, which the researchers attributed in part to reduced rates of smoking.

More recently, a 2018 study of 67 ultra-marathon runners found that they had 11% longer telomeres (the protective caps on the end of our chromosomes that are a marker of biological aging), which corresponded to a 16.2-year younger biologic age compared with their healthy counterparts. And a 2018 century-long French study of former Olympians found a 6.5-year increase in longevity, mainly driven by a lower risk of cancer.

What is the bottom line when it comes to exercise and longevity? If your goal is to live longer (and better), don’t be sedentary. Make sure you get at least the CDC’s recommended daily amount of exercise.

In addition, there is no need to cut back on moderate physical activity if you exceed these recommendations (unless instructed to do so by your doctor), but you don’t need to go to extremes to live longer, either.

If you enjoy endurance sports, you don’t need to stop (again, unless instructed to stop by your physician), but you may want to get your heart checked out periodically, especially if you are over 40, have one or more risk factors for heart disease (high blood pressure, high cholesterol, diabetes) or have a family history of heart disease.