Q: I exercise just about every day and feel great mentally and physically. A friend of mine claims, however, that all the time I am spending in exercise will not add up to a longer life. What can I tell him?
A: Tell him that the latest evidence supports that you can count on a longer life with regular physical activity. You already are reaping the benefits of a better quality of life. But as the years slip on by, the thought of a longer life becomes ever more important.
Life expectancy is defined as the average number of years of life expected for people of a certain age. For example, babies born today are expected to live 78 years on average, whereas 65-year-old people are expected to live an extra 18 years to age 83 years (1). Life span, on the other hand, refers to the maximum age thought to be obtainable by a certain animal species. For humans, the life span is thought to be about 115 to 120 years, and about 70 years for Indian elephants, 28 years for domestic cats, and 3 years for house mice. Most experts feel that exercise has little effect on the life span, but has a powerful impact on life expectancy.
We now have strong evidence that physically active and fit people are less likely to die early than those who are physically sedentary (2-5). Death rates for heart disease, some types of cancer, diabetes, and other diseases are lower in physically active and fit people when compared with those who largely avoid exercise, even after adjusting for differences in body weight and other lifestyle factors. According to I-Min Lee, M.D. (2), of Harvard University, "the most active or fit individuals experience mortality rates that are, perhaps, one quarter to one half lower than the rates among those least active or fit." Findings from the Harvard Alumni Health Study, for example, suggest that increasing amounts of physical activity are associated with decreased mortality, especially when conducted vigorously (e.g., uphill brisk walking) (3).
In practical terms, the most recent data indicate that middle-aged adults who are physically active on a regular basis gain on average about 2 to 4 years of life compared with their sedentary counterparts (4, 5). For comparison (and viewing this from the opposite direction), the average loss of life expectancy for smokers is 8 years, for obese individuals 7 years, and for hypertensive individuals 5 years (6-8). Regular physical activity has about half the effect on life expectancy as making the decision not to smoke. See Figure 1 for a graphic summary.
Although there has been some confusion, a growing sentiment among researchers is that most of the health benefits come from accumulating 30 to 60 minutes of moderate-intensity physical activity on most days of the week. However, additional health and longevity benefits come when people put in a greater amount of more intensive exercise (3, 9). Gains in life expectancy (not to mention quality of life) improve among those willing to put more time and effort into their physical activity regimens.
One of my favorite subjects during the past 20 years of research was Hulda Crooks (Figure 2). Hulda was born and raised on a Canadian farm, where she grew up on a diet of meat, milk, cream, butter, and eggs. By age 18 years, at a height of only 5'2'', she weighed 160 lbs, and decided she needed to improve her diet and lifestyle. She became a lacto-ovo-vegetarian, a diet she followed for more than 85 years.
She married a physician who encouraged her love for the outdoors, hiking, and brisk walking. After a busy career as a dietitian, she retired and began her second career as a mountain hiker. At age 66, after intensive training including stair climbing, Hulda climbed Mt. Whitney in California (14,495 feet) for the first time. At age 91 years, Hulda climbed Mt. Whitney for the 23rd time, becoming the oldest person, man or woman, to make it to the top. My wife, Cathy, and I had the privilege of accompanying Hulda on that historic trip.
Hulda also climbed Mt. Fuji in Japan at age 91 years, becoming the oldest woman to accomplish this feat. These two back-to-back achievements caught the imagination of the world press, and Hulda's story was told and retold both on the airwaves and in newspapers from China to the United States. I had tested Hulda's aerobic fitness in my human performance laboratory, and at age 90 years, she achieved a V˙O2max of 23 mL·kg·−1 min−1, an aerobic power equal to that of a woman 25 years younger.
Hulda told me her achievements were the payoff of having adopted several simple health practices: daily vigorous exercise, a healthy vegetarian diet, and the avoidance of cigarette smoking and alcohol. When I asked Hulda where her motivation came from she replied, "You only have one body. There are no retreads." Hulda encouraged those who would like to start an exercise program to first "make up their minds to do it. It's not easy to really make up your mind and think that you have time to do it. You find time and as you work at it, it becomes part of your program." Sound advice from a woman who lived a high-quality life until the age of 101 years.
1. Arias, E. United States life tables, 2003. National Vital Statistics Reports
54 (no. 14). Hyattsville, MD: National Center for Health Statistics, 2006.
2. Lee, I.M., and R.S. Paffenbarger. Do physical activity and physical fitness avert premature mortality? Exercise and Sport Sciences Reviews
3. Lee, I.M., and R.S. Paffenbarger. Associations of light, moderate, and vigorous intensity physical activity with longevity. The Harvard Alumni Health Study. American Journal of Epidemiology
4. Franco, O.H., C. de Laet, A. Peeters, et al. Archives of Internal Medicine
5. Jonker, J.T., C. de Laet, O.H. Franco, et al. Physical activity and life expectancy with and without diabetes. Diabetes Care
6. Pardo Silva, M.C., C. de Laet, W.J. Nusselder, et al. Adult obesity and number of years lived with and without cardiovascular disease. Obesity
7. Boyle, P. Cancer, cigarette smoking and premature death in Europe: a review including the Recommendations of European Cancer Experts Consensus Meeting, Helsinki, October 1996. Lung Cancer
8. Franco, O.H., A. Peeters, L. Bonneux, et al. Blood pressure in adulthood and life expectancy with cardiovascular disease in men and women. Life course analysis. Hypertension
9. Warburton, D.E.R., C.W. Nicol, and S.S.D. Bredin. Health benefits of physical activity: the evidence. Canadian Medical Association Journal