Scientifically Speaking | How many steps should you walk in a day? The answer is more complex than you think - Hindustan Times

Scientifically Speaking | How many steps should you walk in a day? The answer is more complex than you think

ByAnirban Mahapatra
Apr 03, 2024 01:20 AM IST

The 10,000-step target started off as a marketing gimmick, but now there’s science to back it up.

Science is a gradual process of validation or rejection of ideas. It requires constant evaluation and modification by scientists because, at any given time, our knowledge of the world is imperfect.

What is the ideal number of daily steps for better health? PREMIUM
What is the ideal number of daily steps for better health?

Nowhere is this more apparent than in health studies. As we design better studies, recruit larger and more diverse participant groups, and develop more precise measurements, our understanding of the world deepens.

This leads to a dilemma. Science takes time, but people need to make informed decisions in the face of uncertainty. It's unsettling to navigate health choices without clear, definitive guidance. And when guidance changes, it can seem frustrating for all of us. During the Covid-19 pandemic, the world experienced this sentiment as new information on the effectiveness of various medical interventions became available.

All of us have finite lives. We need to know what to do now. The promise that future research will offer answers offers little comfort in the present. As John Maynard Keynes wrote in 1923, “In the long run we are all dead.”

In the next few columns, I will share some examples of how scientific knowledge has shifted over the years and how it’s led me to change my personal behaviour in the quest to improve my own health.

Here is the deceptively simple question for today: What is the ideal number of daily steps for better health? Despite extensive research, a definitive answer remains elusive, highlighting the complexities of linking activity levels to health outcomes.

Many fitness trackers worn on the wrist have a preset 10,000-step goal that many of us consider a benchmark for daily activity. This 10,000-step goal roughly corresponds to 8 kilometres or 5 miles of walking each day. It has become deeply ingrained in fitness culture as a minimum daily goal and is endorsed by countless health apps and devices. And I’m one of those who, for many years, felt the need to shoot for 10,000 steps either in a few brisk walks or through the course of each day.

We all instinctively know that some activity is better than none, but how much activity do we need? What is the science behind the 10,000-step goal?

Well, a 2019 article in The Atlantic proclaimed in its title: “You don’t need to walk 10,000 steps every day.” The story went on to say that “a clever bit of marketing has obscured the more nuanced nature of human well-being.” Central to the piece and other similar articles published at the time was the discovery that the 10,000 step-goal originated not from scientific research but from a Japanese company's marketing strategy in 1965. Apparently, the number was chosen more for its aesthetic appeal in Japanese characters, (the Japanese character for 10,000 looks like a person walking), than for any grounded health benefits.

Around the same time, a 2019 study published in the medical journal JAMA Internal Medicine further challenged the 10,000-step goal. In this study, involving 16,741 women with an average age of 72, researchers found that walking more leads to a lower chance of dying within the next four years. Specifically, women who walked about 4,400 steps a day had a lower risk of dying compared to those who walked only around 2,700 steps a day. However, the mortality rates progressively decreased up to approximately 7,500 steps, after which there were no clear advantages. The study also found that walking speed didn't have as big of an impact as compared to the number of steps taken.

All these discoveries were widely covered in both traditional and social media. For those of us who strived to get in our 10,000 steps, they raised questions about the sources of our health norms because it seemed like we were successful targets of a marketing strategy rather than following scientific evidence. After all, health guidelines should be rooted in research rather than catchy marketing slogans.

If I wrote this column last year, this is where it would’ve ended.

Now, we have a study led by Matthew Ahmadi and his team at the University of Sydney published in the British Journal of Sports Medicine which finds that walking between 9,000 and 10,000 steps per day significantly reduces the risk of mortality risk or risk of cardiovascular diseases by 39% and 21% respectively, after adjusting for other lifestyle factors. The study, conducted over seven years, tracked over 72,000 participants with an average age of 61 who wore trackers on their wrists.

The upshot is that the 10,000-step target, which was not based on any scientific evidence, now has compelling support in its favour! I doubt that this will be the end of the story. I don’t think future researchers will doubt the foundational advice that physical activity is good for you. However, the details will vary based on the populations and their risk factors, what types of exercise they performed, and how fast they walked.

For some people, we may find that 7,500 steps are enough, while for others we may continue to strive for 10,000 steps a day or more. And I’m not even getting into the accuracy of wrist-worn trackers, which is another topic altogether.

The bottom line is that health is complex and consists of many factors. There will always be a tension in public health communication between the need for simple, clear-cut health advice and the complex, nuanced reality (and limitations) of scientific evidence.

But sometimes, we need simple targets to achieve our goals. For me, my goal is a baseline of daily activity, and for now, I’m sticking with 10,000 steps.

Anirban Mahapatra is a scientist and the author of COVID-19: Separating Fact From Fiction. His second popular science book, When The Drugs Don’t Work: The Hidden Pandemic That Could End Medicine, will be published this year. The views expressed are personal.

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