People who start exercising at midlife reap longer-life benefit, study suggests

Did you go through your 20s and 30s without doing any kind of regular aerobic exercise?

If so, are you worried that those “lost years” have put you too far behind to reap the health benefits — particularly the chance of a longer life — that your peers who started exercising earlier are enjoying?

Well, it might not be too late. A new study — one that asked Americans about their exercise habits across four to six decades — has found that taking up regular exercise in middle age is associated with the same lower risk of early death as keeping active from the teen years onward.

The study also has a message for people under the age of 40 who are exercising regularly: Don’t stop. For, as the study also found, the health benefits of exercise begin to wane if the activity is not kept up.

The finding that individuals who become physically active later in life can “catch up” with life-long exercisers in regard to reducing their risk of early death was unexpected, say the study’s authors.

“We had anticipated that participants who maintained the highest levels of activity throughout adulthood would be at lowest risk and were thus surprised to find that increasing activity early or late in adulthood was associated with comparable benefits,” they write.

The study was published online Friday in the journal JAMA Network Open.

Habits across a lifetime

For the study, a research team from the National Cancer Institute used data on the exercise habits of 315,059 Americans, aged 50 to 71, who filled out a detailed questionnaire in the mid-1990s for a study on diet and health. The questionnaire had asked them to estimate their levels of moderate to vigorous physical activity at four points in their lives: at age 15-18, 19-29, 35-39, and during the previous 10 years (age 40-61).

Using those answers, the researchers divided people who reported being moderately to vigorously active at some point in their lives into three categories: “maintainers” (people who exercised consistently from adolescence onward), “increasers” (people who increased their activity at some point after early adulthood) and “decreasers” (people who were active in early adulthood but who became less active afterward).

The researchers then used national mortality records through the end of 2011 to determine which of the participants had died — and from what. They found that 71,377 participants had died from any cause by that date, including 22,219 from cardiovascular disease and 16,388 from cancer.

Finally, armed with all that data, the researchers compared the death rates of the three categories of exercisers.  They found that people who were “maintainers” — who exercised their entire lives — had a 36 percent lower risk of dying during the study period compared to people who’d never exercised.

But, unexpectedly, the data also revealed a similar decline — 35 percent — in the risk among the “increasers,” the people in the study who reported taking up regular moderate to vigorous exercise for the first time in their 40s or 50s.

This benefit was found among both men and women and was independent of any changes in body weight.

In terms of the two major causes of premature death — cardiovascular disease and cancer — ramping up exercise in midlife also appeared to offer significant benefits. The risk of dying from cardiovascular disease was 43 percent lower, and the risk of dying from cancer was 16 percent lower, among “increasers” compared to people who never exercised.

Those declines were similar to the ones observed among the “maintainers.”

As for the “decreasers” — people who by middle age were no longer engaging in regular moderate-to-vigorous physical activity — their risk of early death was similar to people who had never been physically active.

The study’s findings suggest, say the study’s authors, “that midlife is not too late to start physical activity.”

“Inactive adults may be encouraged to be more active, whereas young adults who are already active may strive to maintain their activity level as they get older,” they add.

Key message: Keep at it

The study comes with important caveats. Most notably, the study’s participants provided their own accounts of how much they exercised at different times in their lives. Some of those accounts went back decades, and therefore may not have been accurate.

The study was also observational, which means it can’t prove that the participants’ exercise habits were directly related to their risk of early death. Although the researchers took into account when doing their analysis many non-exercise-related factors that affect early death, such as educational level, smoking status, alcohol consumption and body mass index (BMI), other confounders may explain the study’s results.

Also, it’s possible that the people who took up exercise in midlife were going to live longer anyway because they were healthier to start with.

Still, as the researchers point out in their paper, their findings are consistent with those of other studies that have linked increased activity at midlife to a longer life.

The take-home message of this study is not, however, that you should forget about exercising when you’re young. Being physically active has immediate health benefits no matter what your age, including improved mood, sleep and energy levels.

“It’s good to maintain an active lifestyle at all times regardless of your age,” epidemiologist Pedro Saint-Maurice, the study’s lead author, told Time magazine reporter Alice Park. “But one good thing is that if you have not been active, you can still benefit if you start becoming active in your 40s and 50s, based on our results.”

FMI: You can read the study in full at the JAMA Network Open website.