Shahar Madjar, MD

I had written here before about the benefits of physical activity. In my last article, for example, I told you about the results of a recent study that showed that the risk of mortality associated with obesity is significantly reduced, or almost completely eliminated, by high levels of physical activity. In other words, I wrote, “overweight individuals who are engaged in moderate or high level of physical activity have the same, or almost the same risk of mortality as that of thinner individuals.” But a question persists: how much exercise is needed to maintain good health, to promote well being, and to prevent death?

A recent article written by Dr. Amanda E. Paluch and her colleagues and published in JAMA Network Open, attempts to partially answer this question.

The researchers tracked a large group of people (2,110 participants) who took part in a the Coronary Artery Risk Development in Young Adults study. The study began in 1985 and participants, who were young adults at the beginning of the study (18-30 year old), were medically evaluated every few years, some of them for longer than 30 years!

The participants wore an accelerometer (an advanced pedometer) that tracked their physical activity and measured the daily steps they took. The researchers then divided the participants into 3 groups: those who, on average, walked less than 7,000 steps a day, those who walked 7,000-9,999 steps daily, and those who completed more than 10,000 steps a day. These groups were referred to as the low-step, moderate-step, and high-step groups. As their end-point outcome, the researchers chose an unequivocal, binary measure: was the participant dead, or alive?

At the end of the study, 72 participants have died (3.4% of participants).

The first conclusion of the study wasn’t surprising. The researchers found that the risk of death was higher for those who were in the low-step group (less than 7,000 daily steps). Individuals who took more than 7,000 steps a day had a 50-70% lower risk of mortality. This was true for all subgroups: women and man, black and white individuals. This result isn’t surprising. After all, multiple other studies had shown that physical activity can improve or maintain good health, and that being physically active is beneficial for many conditions including cardiovascular disease, diabetes, and several cancers. Besides, researchers had proved that physical activity improves an individual’s quality of life. So the more physical activity, the merrier, right?

The second conclusion of the study was surprising: taking more than 10,000 steps a day wasn’t associated with further decrease in the risk of mortality. Why is it surprising? Because I have always believed that 10,000 steps was the appropriate goal. Haven’t you always believed in the same idea?

According to an article by Gretchen Reynolds that I found in the New York Times, the 10,000 steps a day was born in the mind of a Japanese clock maker in the 1960s. He “mass-produced a pedometer with a name that, when written in Japanese characters, resembled a walking man. It also translated as “10,000-steps meter,” creating a walking aim, that through the decades, somehow became embedded in our global consciousness — and fitness trackers.”

I was taken aback by this misconception of mine, until I learned that Gretchen Reynolds herself had learned this cute, interesting fact from Dr. I-Min Lee, a professor of epidemiology at the Harvard T.H. Chan School of Public Health and an expert on step counts and health.

Like many other healthy habits, when it comes to physical activity, some is better than none; plenty isn’t better than enough; and too much, well, is just too much. Overall, the news is good: you do need to move, but, at least by what we now know, you don’t have to sweat yourself to death. Anywhere between 7,000 and 10,000 steps a day would be just fine.

Editor’s note: Dr. Shahar Madjar is a urologist at Aspirus and the author of “Is Life Too Long? Essays about Life, Death and Other Trivial Matters.” Contact him at smadjar@yahoo.com.