From Steps to Sleep: What Do Fitness Trackers Do for Your Health?

It's been almost four years since I started wearing a fitness tracker. I work out, go out, and sleep with it — the only times you may see me without it are when I am charging it.

Honestly, I now sometimes have to deal with the feeling that my workout does not count unless it is tracked and available on my health app.

This raises a question: is having a fitness tracker on your wrist 24/7 actually helpful? If so, in what way?

In this article, I will explore​​ this and other questions related to fitness trackers that can help you make up your mind about whether it may suit your lifestyle.

A look back in time: the history of step counting

Have you stepped back to wonder why 10,000 steps per day is considered the gold standard?

It all comes down to marketing. Well, sort of.

In the 1960s Japan, Dr Yoshiro Hatano suggested that walking 10,000 steps daily could help maintain a healthy weight. Moreover, one of the earliest pedometers, Manpo-kei (literally translated as ‘ten thousand steps meter’), was developed. The Japanese Ministry of Health and Public Welfare decided to run with it and set a national goal to increase the total step count of their citizens by 1,000 additional steps per day. 10,000 became a slogan — although rather arbitrary.

Since then, fitness tracking has evolved dramatically, with modern wearables incorporating heart rate monitoring, sleep tracking, and even stress analysis. These devices are no longer used solely for daily step count tracking — they are designed to observe various aspects of one’s health.

How do fitness trackers work?

Fitness trackers collect data using multiple sensors, which may include, depending on the model, a heart rate monitor, accelerometer, gyroscope, GPS, and skin temperature sensor. These sensors send raw data to a software, which then uses algorithms and data processing techniques to interpret it.

For instance, you can track stress levels with some fitness trackers, but the data they will use to give you insights will depend on the model. Some of the data analyzed by the fitness trackers to estimate your stress levels may include heart rate (HR), heart rate variability (HRV), and temperature.

For this section, we asked Dr James Giordano, Professor of Neurology at Georgetown University Medical Center, to comment on heart rate variability and whether it can provide meaningful insights for mental well-being. Here is what he said.

James Giordano, PhD

Professor of Neurology

Heart rate variability is a valid measure of autonomic nervous system function, and can be a viable and valuable health assessment (relative to cardiovascular and sympathetic nervous system integrity and adaptability to life events and stress).

Heart rate variability assesses the interval between, and overall rate of cardiac contractions, which — in healthy people — should vary in response to particular life events and challenges.

It is important that measures of heart rate variability be standardized to each person’s baseline to most effectively use this measure as an evaluation of individual physiologic function, as HRV can differ among healthy individuals, and it is important to distinguish this healthy variance from those changes that may be indicative of less than optimal health.

However, keep in mind that in fitness trackers, heart rate variability is also calculated by algorithms, which may not always be reliable. Factors like heart rate sensor accuracy and environmental conditions can affect the results. While HRV can provide valuable insights into stress, it is essential to interpret the data with caution and consider it as part of a broader health assessment rather than a definitive measure.

My personal experience with fitness trackers

In 2021, I was gifted my very first smartwatch. I didn't realize it then, but it must have been one of the most thoughtful gifts I've ever received, especially since I was just trying to establish a regular exercise routine.

It worked like a charm. Probably because I love tracking things, and with this brand new toy, I had way more data to play around with.

At first, I signed up for the gym to do cardio (yay, elliptical machines!), but after seeing all the truly fit people working out with free weights, I decided to try it myself. Surprisingly, I loved it, and way more than cardio — so much so that now I go to the gym 4–5 times a week to lift weights. When it comes to cardio, well… Recently, I might have been skipping that more than I would like to admit.

Still, I went from someone who thought she hated sports to someone who tracks all the macros, takes creatine, and manages to talk about bicep curls during work parties.

What was about my watch that made it effortless to remain consistent with my exercise routine? I had to ‘close my rings’ (meet the fitness goals), set records, and receive silly achievements. Gamified fitness allowed me to create my routine, which I now do out of habit — without the encouragement of my fitness tracker.

I still never go outside without my watch — actually, the same one I was gifted 4 years ago. I sometimes do not reach all of my goals — after all, life happens and I allow myself to rest and recuperate if needed.

I also know that my workout does count even if my watch is out of battery. However, I prefer it to be charged and ready.

How accurate are fitness trackers?

I am not alone in having a positive experience. In fact, as indicated in one systematic review, wearing a fitness tracker may lead to increased physical activity. As per the same study, the increased activity approximately equated to 1,800 extra steps, 40 min more daily walking, and reductions of around 1 kg of body weight.

But not everyone has a positive experience with their fitness trackers. Having a tracking device that counts every move you make and every breath you take (quite literally) may come with drawbacks. Especially if ‘every’ is far from reality.

As shown by WellnessPulse original research, the accuracy of some trackers stands at around 67%. One experiment that analyzed the effects of deflated step count on overall health showed that incorrectly lower readings may lead to negative emotions, unhealthier food choices, and even increased blood pressure and heart rate. Another study on patients with atrial fibrillation also highlighted increased anxiety levels due to irregular rhythm notifications.

Moreover, due to a lack of accuracy, certain data should also be taken with a grain of salt. For example, if you are looking to lose weight, keep in mind that fitness trackers may be rather off with calories burned per day.

At the end of the day, these trackers are mostly beneficial as an encouragement to keep up with healthy habits and should always be used with caution.

Different types of fitness trackers

Smartwatches are not the only fitness trackers out there. Although some of them are rather uncommon or still in the development stage, different kinds of trackers can be better suited for specific situations or needs.

Selecting the right fitness tracker: key considerations

Which device is most suitable for your lifestyle will depend on various factors, including:

• Battery life. Some smartwatches may need to be charged every day — which could be a serious disadvantage if you are into hiking or long-distance running.
• Size. Some devices such as smartwatches with larger battery capacities may be rather bulky. For those who wish to have a smaller device, smart rings could be a suitable option. Some of them can last up to around 7 days between charges depending on the model.
• Individual needs. If, let’s say, sleep tracking is the main reason you are looking for a fitness tracker, you can find products that are tailored for this purpose alone. They tend to be smaller in size and, overall, more comfortable for sleep compared to multipurpose devices.
• Water resistance. If you are into scuba diving, check how deep you can go with your fitness device.

If you are not sure if the product suits your needs, search online for communities (e.g., Reddit) related to your hobby, sport, or fitness goal.

Final thoughts

For those who enjoy tracking their progress, fitness trackers simplify the process. It may boost motivation and make it easier to achieve certain health goals such as improving sleep hygiene and increasing movement throughout the day.

However, fitness trackers may also contribute to stress, especially since they are rather inaccurate. Moreover, for certain goals such as weight loss, fitness trackers may be unhelpful due to incorrect estimations of calories burned.