Will Fitbit’s ‘magic number’ really step up your fitness game?


Where will Fitbit’s 10,000 steps a day lead you?
Where will Fitbit’s 10,000 steps a day lead you?
Photo: Graham Bower/Cult of Mac

Fitbit reported its best-ever holiday sales this week, but investors are fretting because the wearable maker’s guidance for the current quarter is lower than expected. Some analysts are questioning whether Fitbit can hold its own against competition from Cupertino.

Apple Watch has proved to be a fantastic fitness tracker for many Cult of Mac readers. So I was curious to find out how Fitbit’s trackers compare. They may be cheaper than Apple Watch, but are they as effective at promoting healthy habits?

This post contains affiliate links. Cult of Mac may earn a commission when you use our links to buy items.

What’s up with Fitbit?

Fitbit dominated the App Store charts over the holidays. Even President Barack Obama has taken to wearing one. Fitbit looks unbeatable in its sector. But then, so did BlackBerry — right up until the moment when it wasn’t.

Who can blame investors for getting antsy when Apple moves into the neighborhood? From MP3 players to smartphones, Apple has a successful track record of muscling in on sectors where there is serious room for improvement. And fitness trackers are no exception.

Research suggests one-third of wearables are abandoned within six months. Fitbit seems to be particularly affected by this problem, with data suggesting “more than 70% of Fitbit purchasers from the first three quarters of 2014 [stopped using their device] before the end of the year.”

Since Fitbit sells hardware rather than subscriptions, investors may not be too concerned about the millions of unloved Fitbit wearables gathering dust in the nation’s junk drawers. But for anyone who actually wants to get in shape, this raises serious questions about whether Fitbit actually helps.

Is a Fitbit tracker a step in the right direction?

At the heart of most Fitbit trackers is step counting. When you first install the Fitbit app on your iPhone, it nags you to walk 10,000 steps a day. This is the “default goal” Fitbit sets for all new members, and the company bizarrely claims it is a “magical number.”

But why is 10,000 magical exactly? Why not 8,000 or 12,000?

To back up the 10,000-step magic number, the Fitbit app offers a link to a blog post from way back in 2010. The article cites evidence from an American Heart Association app, but this turns out to have been “retired.” Not much magic there, then.

It is understandable that step-counter manufacturers like Fitbit choose to focus on step-counting goals, but this is not in line with most mainstream advice on how much we should exercise.

The World Health Organization, the American Heart Association, the American Cancer Society and the British National Health Service all recommend that adults (between 18 and 64 years old) get at least 150 minutes of moderate-intensity activity or 75 minutes of vigorous activity each week. That’s the equivalent of 30 minutes of moderate exercise a day, five days a week. In addition, most of these organizations suggest we do strength-training exercises two or more days a week.

I could not find any mention of the number of steps we should take, 10,000 or otherwise.

Fitbit recommends walking 10,000 steps a day
Fitbit recommends walking 10,000 steps a day.
Image: Graham Bower/Cult of Mac

Can 10,000 steps lead you to a better life?

Like Fitbit, Apple Watch counts your steps. You can see your total steps for the day if you scroll down in the first screen of the Watch’s Activity app. But steps are not used as a goal on any of Apple’s Activity rings.

Instead, Apple’s Exercise goal is 30 minutes of moderate-intensity exercise a day. Sound familiar?

Apple Watch can measure exercise intensity because it includes a heart rate monitor – something that most Fitbit devices, with the exception of the Charge HR and Blaze, do not. Fitbit claims that 10,000 steps is “roughly equivalent” to 30 minutes of activity most days of the week. But how accurate is that?

Not very, according to Brandon Ballinger, the developer of Cardiogram, a heart-rate analysis app for iPhone and Android. Ballinger has been using the data he has collected from his app to find out if there really is any benefit to walking 10,000 steps a day.

Not dying is a good start

Whether you are walking 10,000 steps or exercising for 30 minutes, the purpose of exercise for most people is to stay healthy. But what does this actually mean? Well, not dying is a good start.

Mortality is not something an app can realistically measure. So instead, to investigate the effectiveness of 10,000 steps a day, Ballinger looked at resting heart rates. Research suggests that a lower resting heart rate is associated with a lower risk of mortality.

The good news for Fitbit is that people who walked more steps per day did indeed reduce their resting heart rate. But only to a point. Beyond about 5,000 steps a day, it did not make much difference how many more steps users took. So Ballinger decided to look at intensity of exercise.

It is like the difference between quantity and quality. 10,000 steps is a lot of exercise, but if you do it over a long period of time, it is not very intense. Conversely, if you completed all 10,000 steps within a one-hour run, that would be very intense exercise.

Ballinger divided his users into three groups based upon the intensity of their exercise. Members of the high-intensity group got their heart rate up to 150 beats per minute for at least one hour a week. The medium-intensity group raised it to 130 bpm for an hour a week. And everyone else was bundled into the low-intensity group. Ballinger found that “even if you get 10,000 steps per day, if your heart rate doesn’t go over 130 bpm, there’s not much impact on your resting heart rate. In contrast, even 4,000 steps/day of high-intensity exercise delivers a benefit.”

Ballinger’s study may not be strictly scientific (users of the Cardiogram app, for example, are not selected to be very representative of the general population, and Ballinger does not mention how many people are included in his sample). But it is intriguing, and consistent with the World Health Organization’s exercise recommendations.

Fewer magic numbers, more evidence please

No one actually wants to walk 10,000 steps a day. You do these things because companies like Fitbit tell you it will “improve your overall health.” And that is a serious matter.

In general, it seems reasonable to suppose that more exercise is better than less. So a 10,000-step goal is probably better than nothing. But I think it is about time that Fitbit updated its advice on goals, with less emphasis on the “magic number” and more supporting evidence.

In the meantime, if you are considering buying a Fitbit tracker, I would recommend choosing one with a heart-rate monitor, like the Charge HR or the new Fitbit Blaze. Or better still, get an Apple Watch, so you can track your progress toward your daily 30-minute exercise goal.