Does Exercise Benefit as Much as Smoking Harms?

[david_myers]

If you, dear reader, can indulge some slightly geeky calculations, I hope to show you that with daily exercise you can live a substantially longer and happier life. Indeed, per the time invested, exercise will benefit you more than smoking will harm you. Consider:

• An analysis of mortality data offers this memorable result: For the average person, life is lengthened by about 7 hours for every hour exercised. So (here comes the geek), the World Health Organization recommends exercising 150 minutes = 2.5 hours per week. Multiplied times 7, that equals 17.5 hours longer life for each week of exercise. Over 52 weeks, that sums to 910 hours = 38 days = 1/10^th of a year longer life for each year of faithful exercise . . . which, continued over 40 years would yield ~4 years longer life. (Though, more typically, say the researchers, runners live 3.2 years longer.)
• In another epidemiological study of over 650,000 American adults, those walking 150 minutes per week lived (voila!) 4 years longer than nonexercisers (Moore et al., 2012).

How satisfying to have two independent estimates in the same ballpark!

This potential life-extending benefit brings to mind the mirror-image life-shortening costs of smoking, which the Centers for Disease Control reports diminishes life for the average smoker “by at least 10 years.” Thus (geek time again):

• A person  who takes up smoking at age 15, smokes 15 cigarettes per day for  50 years, and dies at 65 instead of 75, will lose roughly 1/5^th of a year (equals 73 days = 1752 hours = 105,000 minutes) for each year of smoking. If each cigarette  takes 10 minutes to smoke, the minutes spent smoking (54,750 each year) will account for half of those 105,000 lost minutes.
• Ergo, nature charges ~2 minutes of shorter life for each minute spent smoking. . . but generously gives a 7-to-1 return for each hour spent exercising. How benevolent!

Massive new epidemiological studies and meta-analyses (statistical digests of all available research) confirm both physical and mental health benefits of exercise (see here, here, and here). A good double goal for those wishing for a long life is: more fitness, less fatness. But evidence suggests that if forced to pick one, go for fitness.

As an earlier blog essay documented, exercise entails not only better health but a less depressed and anxious mood, more energy, and stronger relationships. Moreover, clinical trial experiments—with people assigned to exercise or to control conditions—confirm cause and effect: Exercise both treats and protects against depression and anxiety.

The evidence is as compelling as evidence gets: Go for a daily jog or swim and you can expect to live longer and live happier. Mens sana in corpore sano: A healthy mind in a healthy body.

 K.C. Alfred/Moment/Getty Images

(For David Myers’ other weekly essays on psychological science and everyday life, visit www.TalkPsych.com)