June 14, 2023 5 min read

Fitness trackers ... such as watches, smartphone apps, Fitbits, and WHOOPs have exploded onto the fitness scene.

There are now countless options you can use to track almost any aspect of your health & fitness.

Steps, sleep, calories burned, heart rate, workouts ... these devices can track just about anything.

But then comes the question ... do they work & are they actually accurate with the information they provide? 

Let's take a look.

The Step Count on Your Fitness Device

Increasing your daily steps is a great way to improve your fitness. Shooting for a goal of anywhere between 10,000-15,000 steps per day can provide a ton of different health benefits.

And of course, tracking your steps in some form is part of hitting your daily step goal.

Using a step-tracking device, watch or app is virtually the only way to track your steps ... so how accurate are they at doing so?

A 2020 study done by the International Journal of Environmental Research and Public Health looked at 11 different trackers & mobile phone apps when it came to step count ... and then compared the accuracy between each device.

What was found, was that the accuracy was much greater during brisk, intentional walks.

There's some inaccuracy during general, daily activity ... and this usually stems from arm movements that get counted as steps. (1)

This shows that your device can be very accurate in tracking your steps, but it may be best to use that count when you're walking intentionally. This doesn't mean you can't factor in the other steps you take throughout the day ... just know that count maybe less accurate.

The Heart Rate Monitor on Your Fitness Device

Monitoring heart rate was actually one of the first reasons why these types of fitness trackers were made. To keep it simple, they use advanced light-emitting technology ... and this allows the device to "see" your heart rate. These devices have built-in algorithms that then use that information to give you a heart rate reading. Pretty cool stuff, huh?

But ... is this actually accurate?

You may be surprised to hear that a study done in 2018 did show that these devices can get accurate readings when measuring your heart rate. But there was a noticeable amount of variation between devices. Basically, showing that some devices are much more accurate than others ... which is to be expected. (2)

You're probably not going to get a super accurate heart rate reading with a cheap fitness tracker, but if you're willing to pop for one of the higher-end options ... you're typically will get some pretty accurate numbers.

The Sleep Tracker on Your Fitness Device

This is where it starts to get a little tricky ... because sleep & sleep stages are very complex. Most studies have shown that aside from tracking total time sleeping ... most devices are not accurate when it comes to tracking the different stages of sleep (REM, non-REM, etc.). Studies show that they either overestimate or underestimate the time you spend in each sleep stage.

This makes sense, because sleep is very complex ... and it's not easy, even for an expensive fitness tacker, to get accurate sleep readings.

The Calorie Tracker on Your Fitness Device

Tracking calories burned throughout the day or during a workout is one of the most common uses of fitness devices ... but are they giving you the right numbers?

Like sleep, the number of calories you burn on any given day is a complex subject. It's dependent on many different factors like height, weight, your activity factor ... and concepts like Non-Exercise Activity Thermogenesis (or NEAT). And neat includes aspects as detailed as how many times you blink per day.

So, you can see just from this ... it would be hard for even the most advance fitness trackers to measure all these factors accurately. 

A study done in 2018 by the International Journal of Environmental Research showed accuracy in step counting, heart rate monitoring, and sleep duration ... but failed to show accuracy when it came to energy expenditure (aka burning calories). (2,3)

It was later determined that of all the measurements a fitness tracker can provide ... calorie expenditure is probably the least accurate. There's just too many outside factors that influence how many calories you burn on a given day.

Should You Use a Fitness Tracker or Watch?

Now that you understand how accurate these devices are ... it brings us to the final question: Should you use a fitness tracker?

Should you rely solely on the numbers your watch, phone, or Fitbit are giving you when it comes to these different aspects of fitness? Probably not.

Like we talked about ... there's a lot of different variables that play into their accuracy.

But ... a study done in 2018 by the JMIR mHealth and uHealth did find that people who use fitness trackers tend to become much healthier & more active. (4)

The study showed that those using these devices typically got more steps in, improved their sleep ... and engaged in more vigorous exercise. It also showed that those using these trackers were more likely to maintain healthier habits in the long run.

So, when it's all said and done ... you certainly don't need to use a fitness tracker ... but research does show that they can play a role in helping you create long-term healthy habits.

And creating long-term healthy habits should always be your ultimate goal with fitness. 

Don't forget that we're always here to help as well! So, if you need a recommendation for fitness trackers (we use them ourselves!) or help with anything regarding your fitness ... just drop into see us at your nearest Supplement Superstores location! We're always more than happy to help.

*This post was written by Andrew Lynn, who has a B.S. in Nutrition & Dietetics. He's also a N.A.S.M. Certified Personal Trainer and N.A.S.M. Certified Fitness Nutrition Specialist.

1. Hartung V, Sarshar M, Karle V, Shammas L, Rashid A, Roullier P, Eilers C, Mäurer M, Flachenecker P, Pfeifer K, Tallner A. Validity of Consumer Activity Monitors and an Algorithm Using Smartphone Data for Measuring Steps during Different Activity Types. International Journal of Environmental Research and Public Health. 2020; 17(24):9314. https://doi.org/10.3390/ijerph17249314

2. Thiebaud RS, Funk MD, Patton JC, et al. Validity of wrist-worn consumer products to measure heart rate and energy expenditure. Digit Health. 2018;4:2055207618770322. Published 2018 Apr 13. doi:10.1177/2055207618770322

3. Xie J, Wen D, Liang L, Jia Y, Gao L, Lei J
Evaluating the Validity of Current Mainstream Wearable Devices in Fitness Tracking Under Various Physical Activities: Comparative Study
JMIR Mhealth Uhealth 2018;6(4):e94

4. Brickwood K, Watson G, O'Brien J, Williams AD
Consumer-Based Wearable Activity Trackers Increase Physical Activity Participation: Systematic Review and Meta-Analysis
JMIR Mhealth Uhealth 2019;7(4):e11819