“I don’t run to add days to my life, I run to add life to my
days.”
That quote is catchy and memorable because the
first part is expected; we know that running and being active makes you live
longer. The point of the quote is that it goes beyond that.
But today let’s focus on that first part. How many days are
we talking about, really? Research recently published in PLOS
Medicine attempted to quantify that number. The authors pooled findings from a couple
of large studies (such as the Women’s Health Study and the NIH-AARP Diet and
Health Study) and accumulated data on close to 650,000 people. The studies included reports from a ten-year follow up and so the authors were able to correlate amounts of exercise with how long people
lived. A quick perspective to understand the numbers on the graph below: physical activity
was quantified as metabolic equivalents (METs); 7.5 MET-hr/wk is roughly equal
to 150 minutes of brisk walking per week, or 75 minutes of vigorous activity
(such as running.) 7.5 MET-hr/wk is about the recommendation doctors and public
health advocates encourage for a healthy lifestyle.
In the graph, you can see that as "leisure time physical
activity" (i.e. exercising in your free time, such as running or walking) increases, years of life increase as well.
As you can tell from the sharp increase to the left of the graph, just getting
off the couch for an hour or so each week helps a lot. (Activities such as brisk
walking for 75 minutes/week increased life expectancy by 1.8 years.) People
getting the recommended amount of exercise (150 minutes of walking or 75 minutes
of running) increase their life expectancy by 3.4 years. Incredibly, although
the effect lessens, it keeps going up with more activity. (No, marathoning likely won't kill you.)
The study goes on to talk about the relationship between
BMI, physical activity, and longevity. This is the relatively new concept of
being “fit and fat.” Annoyingly, some people can’t seem to lose weight despite
a rigorous and routine exercise program. Are these people better off health
wise than those much hated skinny people who never have to exercise?
So far, the research says yes: even if you don’t lose weight, exercise has
other (perhaps less superficially obvious) benefits to your health. So fit and
fat people are better off than those inactive, normal weight people (the lean
and lazy? skinny and slacking? slim and slothful?)
This study provides more evidence. Overweight people (BMI
between 25 and 29.9) who were active lived 4.7 years longer than inactive, normal weight people (BMI between 18 and 24.9.) Even active obese people (BMI between 30-34.9) lived 3.1 years longer than those lean and lazy people. However, this
effect disappeared when people had BMIs greater than 35 (severely obese
category.) It seems that at that point, the health risks of being overweight
outweigh (no pun intended!) the benefits of working out.
In summary, it tells us what we already knew: running can
add days to our lives. Now we know just how many: approximately 1,241 (3.4
years) for 75 minutes of running per week. But the life added to our
days? That’s harder to quantify.
Dream big,
Teal