How Much Data Is Too Much?

Fitness trackers can be a powerful training tool, but only if you use the info correctly.

Photo: Getty Images

Heading out the door? Read this article on the new Outside+ app available now on iOS devices for members! Download the app.

Running purists will say the only thing you need to be a runner is a good pair of shoes, but there’s another piece of gear that’s nearly as ubiquitous: the fitness tracker.

Wearable technology—including fitness trackers, smart watches, heart rate monitors, and GPS tracking devices—was named the number-one fitness trend for 2022 by The American College of Sports Medicine; it’s been in the top three since the category was introduced in 2013.

In 2020, one in five U.S. adults was regularly wearing a smartwatch or fitness band, according to the Pew Research Center. That number has only grown; global smartwatch shipments grew by 47 percent year over year in the second quarter of 2021, according to Strategy Analytics.

For runners, data tracking can help you dial in your workouts, assess your current fitness level, track your sleep and recovery, and so much more. But it can also lead to information overload and can be overwhelming, confusing, and downright distracting if you’re not using it in a healthy way.

RELATED: Why You Should Be Skeptical About Your Wrist-Based Heart Rate

How Data Can Be Helpful

There are definite benefits to tracking activity: People who used fitness apps and trackers logged an extra 1,850 steps per day compared with non-users in a December 2020 analysis published in the British Journal of Sports Medicine—and they were still moving significantly more 13 weeks later.

The objectivity of fitness tracking can be really helpful to runners, says Angie Winter, a sports psychology consultant and high performance coach at HigherEchelon. “Fitness tracking gives you a way to see where you’re improving and hold you accountable to that hard work you’re putting in,” she says. While going by feel certainly has a place in running, by tracking trends in how your body responds to changes to distance, pace, elevation, heart rate, and certain environmental conditions, you can learn so much more about your current fitness level.

It’s not just about what you do during your workouts, though—continuous physiologic data throughout the day such as activity tracking can also be useful, says Kevin Longoria, a clinical exercise physiologist and chief science officer at Biostrap. “Being a habitual runner does not necessarily guarantee that moderate- to vigorous-intensity physical activity recommendations are being met for health and well-being,” he says. A fitness tracker can give you a more holistic view of your health and encourage you to do more outside of each run, which will help supplement your running goals.

While fitness trackers aren’t inherently linked to health benefits like lower blood pressure or cholesterol levels, they can boost your motivation to work out, according to research published in 2019 in the American Journal of Medicine—and science has repeatedly shown that regular exercise does make you healthier.

Fitness trackers serve as a visual reminder, says Winter. “That accountability is so powerful,” she says. “As a society, we know the basics around fitness and nutrition. But we really struggle to put those basics into action. Wearables, though, give us feedback every day. It’s almost like having a workout buddy on your wrist.” And the more tuned in you are to certain habits, the more power you have to change them.

“The real power of biometric data is the ability to zoom out and see the big picture,” says Longoria. “Was changing your pre-sleep routine responsible for the improvement in sleep quality? Did that new recovery modality have a quantifiable effect on your nocturnal heart rate variability, beyond just ‘feeling good’? These are all great uses and examples of how wearable technology can provide insights into all aspects of training.”

fitness trackers for runners
(Photo: Micheli Oliver)

When It’s Time to Step Away from the Metrics

The problem comes when you get too caught up in your data, which, a) may or may not be accurate; and, b) can’t account for the nuances of being a human.

“Humans can’t be just data points,” says Winter. These data points are just one piece of the puzzle, but they don’t factor in subjective things like a stressful day at work, drinks out with your friends the night before, or that really tough hill workout you did earlier in the week. “There’s so much power in looking at why something happened,” she says—and an algorithm can’t tell you that.

That’s especially true if you aren’t getting accurate data. A 2020 systematic review of 158 studies found that, in laboratory-based settings, Fitbit, Apple Watch, and Samsung appeared to measure steps accurately. Heart rate measurement was more variable, with Apple Watch and Garmin being the most accurate and Fitbit tending toward underestimation. For energy expenditure, no brand was accurate. Even your GPS can be off; a 2016 paper in the International Journal of Geographical Information Science determined that fitness trackers are guilty of a “systematic overestimation of distance.” Sleep tracking accuracy depends on the device you’re using, according to research published in 2020 in the journal Sleep, and wearable nutrition trackers are so new that “few are reliable for obtaining accurate and precise measurements of diet and nutrition,” a 2020 study published in JMIR mHealth and uHealth determined.

“The harsh reality is that there are no regulations that require these device manufacturers to benchmark their data outputs relative to any type of gold standard medical equipment, causing significant disparities in data integrity within and between wearable technologies,” says Longoria.

Plus, once you’ve quantified performance feedback—whether it’s accurate or not—it’s hard not to think about how you’re performing any time you re-engage with that activity. A 2020 study from the University of Copenhagen concluded that activity data from wearable devices can result in increased levels of uncertainty, fear, and anxiety, and lead to obsessive and dependent behaviors.

RELATED: Why I’ll Never Use A Run-Sharing App

If you feel yourself veering towards those kinds of feelings, “the best thing you can do is not track,” says Winter. “Or maybe you only track once a week.” Some athletes use tape to cover tracking screens during workouts, adds Longoria.

The big problem: For some people, wearables can make you feel like fitness is something you have to do, which can actually sap your motivation. When you start quantifying pleasurable activities, it makes them feel more like work, which reduces enjoyment and decreases subjective well-being and engagement in that activity, according to a 2016 study published in the Journal of Consumer Research.

“With the advent of more sensors, devices, and data, it is not uncommon to feel overwhelmed by the data,” says Longoria. “Many runners know the ‘runner’s high’ or the feeling of being ‘in flow’ during a workout. These internal states are blissful and worth pursuing in their own end. If a runner finds themselves unable to reach those states because they are constantly pulled out to check their current pace or heart rate, then it is time to stop using the data for a while and focus on reconnecting with the inner self.”

How to Have a Healthy Relationship With Your Tracker

At the end of the day, the most important thing to remember is that a fitness tracker is just one tool at a runner’s disposal. “Data is valuable, but wearable users should not blindly trust these numbers and remove their intuition from the training equation,” says Longoria. “These sensors are meant to observe and describe an athlete’s responses, not control an athlete’s training.” Track your data, but don’t take it as gospel.

While trackers can give you some objective data points, pair that with self-monitoring and self-reflection. “I highly recommend some kind of journal alongside the numbers,” says Winter. “Runners tend to be high achievement motivated individuals who put a little bit more focus and emphasis on what goes wrong; this can help you look back and see what went right—and that even if you didn’t hit one workout, you still got better.” Plus, it provides that context around your training the algorithm can’t.

Remember: You are your best data point, and you know your body better than any computer. Use wearables to help dial in your training, but pay just as much attention to how you feel on any given day, your larger patterns, and how your lifestyle affects your training. That’s what’s going to help you do your best.

RELATED: 5 Ways To Make Sure You Feel Good During Workouts

Trending on Trail Runner Magazine

Want to Know What It Takes to Finish at Western States? Just Ask Hellah Sidibe.

Find out what happened when this six-year run streaker and HOKA Global Athlete Ambassador took on an iconic ultramarathon in California's Sierra Nevada