One of the most widespread beliefs in the mainstream fitness community is that 10,000 steps a day is the best thing any person can do for their overall health. Walking has been linked to improved cardiorespiratory capacity and cognitive function in old age. While the benefits of walking are not in dispute here, what about the magic number? Why 10,000 steps and not 8,000 or 12,007?
According to a recent article in The Atlantic, the much-touted magic number was originally a marketing gimmick pulled from thin air by a Japanese pedometer manufacturer: The number “was chosen for the product because the character for ‘10,000’ looks sort of like a man walking.”
This reasoning obviously is grossly insufficient for deriving a specific recommendation for the general population. Is there any better evidence available to set walking goals for the average person?
A study of 17,000 elderly women showed a correlation between longevity and the total number of steps taken per day. Women who walked the least were shown to have the highest mortality rate. Mortality rates continued to decrease up to 7,000 steps and then leveled off. The author of this study suggests walking an extra 2,000 steps a day (roughly one mile) to improve your health. However, the study was observational and did not measure whether changes in activity produced health benefits. This type of study can’t tell us whether people are healthier because they walk more or they walk less because they have underlying health problems.
We can also derive information by studying walking patterns for hunter-gatherer groups. Their lifestyle more closely resembles our evolutionary past than our modern, mechanized lifestyle. Estimates of the distance covered by hunter-gatherers vary from 3.7 to 10 miles per day, depending on the season and other environmental/dietary factors. A recent study of the Hadza people of Tanzania tracked participants’ daily movements with GPS smart watches and measured their total energy expenditure. Male Hadza averaged seven miles a day in their foraging tasks, which included hunting small game and collecting honey. Women covered 3.6 miles a day gathering plant foods.
What is interesting is that their metabolic rates were similar to Westerners in spite of their much higher physical activity level, even when accounting for differences in body mass. This is bad news for anyone hoping to lose weight by walking it off.
As Dr. Aseem Malhotra argued in “Take off That Fitbit. Exercise Alone Won’t Make You Lose Weight,” “You can’t outrun a bad diet.”
It is widely believed that creating a calorie deficit through daily activity can compensate for a bad diet, but that’s a dangerous myth — a very popular and profitable one. Several studies of wearable activity trackers have shown that people actually lose less weight when they track their steps.
At the conclusion of a 24-month trial, researchers observed that usage of a wearable device in combination with a behavioral weight loss program resulted in less weight loss when compared to those receiving only the behavioral weight loss program. In fact, participants without physical activity trackers showed nearly twice the weight loss benefits at the end of the 24 months. Participants who utilized wearable devices reported an average weight loss of 7.7 pounds, while those who partook only in health counseling reported an average loss of 13 pounds.
One problem is people feel entitled to reward themselves when they reach their daily steps target. This concept is called “moral license.” It’s the same as giving money to charity and then cutting someone off in traffic or going to church on Wednesday so you can party on Friday. If you burn 300 calories on a treadmill and then eat a piece of cake, you have just erased your calorie deficit. Worse, you have messed with your hormonal balance, which is more important than “calorie balance.”
Another pitfall of the 10,000-step recommendation is the inevitable lack of variance it entails. Variation is natural. A fixed target like 10,000 steps is profoundly artificial. A hunter won’t call it a day when he reaches his daily step target. Some days he’ll kill an elk within easy reach of his hut. He won’t keep walking circles around his kill just to reach his daily steps goal. Other days, he’ll wander for hours and come home empty-handed. And these steps aren’t on a treadmill. They take him over hills, through creeks and away from predators. You severely discount the quality of the steps when you only measure the quantity.
So the 10,000-step program is lacking in variance, but what about intensity, another of the key pillars of CrossFit? Instead of walking more, how about walking faster?
A meta-analysis of nine studies tracking the gait speed of 34,000 senior citizens showed a strong correlation between walking pace and mortality: “At age 75, predicted 10-year survival across the range of gait speeds ranged from 19% to 87% in men and from 35% to 91% in women.” The gait speeds ranged from below .9 mph to above 3.1 mph. The men in the highest quartile for gait speed were more than four times as likely to be alive after 10 years. They are most likely in better health to begin with, so it’s not purely out of choice that they were faster walkers. Since the study was observational, it can’t tell us whether a conscious effort by a slow walker to speed up would increase their lifespan.
But a slower walking pace has also been associated with accelerated aging. Another study measured 19 biomarkers associated with age and found the slowest walking subjects “had been aging 5.0 years faster from ages 26 to 45 years than participants with the fastest gait.” The study also rated each participant’s facial appearance, and the slow walkers looked significantly older.
This study also observed a 16-point difference in IQ between people in the lowest and highest quintiles of walking speed at age 45. To put this in perspective, a difference of 16 IQ points is roughly equivalent to:
- The average person (IQ of 100) and the average office manager (IQ of 116).
- The average person in 1945 and the average person in 2000. (The IQ of the general public has increased steadily over time. IQ tests are periodically recalibrated to maintain 100 as the average IQ. This trend is called the “Flynn Effect” and has been attributed to a variety of public health factors as well as the increasing cognitive demands of modern life.)
- David Letterman (IQ of 120) and Oprah Winfrey (IQ of 136).
Once again, these studies can’t tell us if faster walking makes people healthier or if healthier people naturally walk faster. CrossFit has always contended that the beneficial effects of exercise are driven by intensity. For most people, walking falls well short of a workout that will drive adaptation through intensity. Thus, while a brisk walk may confer its own discrete benefits, no amount of walking can elicit the same benefits as a high power output workout.
What can we take away from all this? Don’t blindly follow the recommendation of a gadget manufacturer. Get outside to walk and play in the natural environment as much as possible. Fresh air and sunlight provide benefits a treadmill cannot. Instead of adding 2,000 steps a day, as many experts suggest, try walking faster. If your daily walk to work normally takes 10 minutes, try to get there in nine. Don’t bother quantifying your steps when you can improve their quality or be active in other ways, like playing with your kids or pets. And if your brisk walk ends at a local CrossFit box, even better.