Fitness trackers: 4 things you should know

March 16, 2020


By: R. Max Lystrup, MD*

Fitness trackers are fun tools that can help you be more active. Here are some things to know before you invest in one. 
  1. What’s the best fitness tracker out there? 
    This is like asking what kind of car you should buy. The best device is one that has the right capabilities you need, you’ll wear every day, and fits your budget. There are hundreds of options out there with different capabilities and price points, and they come in many forms. Most devices are some sort of wearable wristband, while others fit on your shoe, arm, belt, and even around your finger. You can spend anywhere from $1,300 for a fancy smartwatch or just download a free app to get started. 
  2. How do fitness trackers work?
    Here are the basic components of a modern fitness tracker: 
    • Accelerometer. This tiny chip on a spring senses your motion in 3 dimensions. It estimates step-counts, tracks movements, and can even detect sleep patterns. High-end devices contain multiple accelerometers and use specialized algorithms to show differences for running, cycling, swimming, weight lifting, and other activities. 
    • Global Positioning System (GPS). If you like to run or bike outside, this is a good option for fitness tracking. GPS is more accurate than accelerometry at detecting actual distances travelled. Most phones also have GPS, and you can download many free apps to track your fitness on them. When using a fitness tracker or app with GPS, make sure it follows your service’s policies on location tracking and sharing. 
    • User interface. The device itself can take many forms, so pick one that looks nice and is easy to use. Various software platforms integrate your physical activity, water intake, sleep, and food choices and give feedback. Many also have social media integration and virtual activity groups, which can help motivate you through social comparison. 
    • Other components. Some devices monitor heart rate, respiratory rate, sweat, temperature, altitude, and ambient light. Make sure you’re not paying extra for a device that has these features unless you’re sure you’ll use them. 
  3. How can a fitness tracker help me reach my goals? 
    The ultimate goal of using a fitness tracker is to make your life better by improving your day-to-day choices. Like any tool, these devices can both help and hinder your progress. 

    If walking is your thing, and you want to increase your activity throughout the day, a step-counter is a great option. This can help motivate you to accumulate activity over the day by changing your lifestyle. For instance, you could park your car far from the office, take a walk over your lunch break, or walk to someone’s desk rather than email. A good baseline threshold for a walking program is 10,000 steps per day, depending on the person. 

    However, don’t let the numbers game become a hindrance. I joined a workplace step-tracking group and competed to get the most steps in a day. I stopped weight lifting, swimming, and biking because they “didn’t count” and instead just walked around a lot to rack up the steps—and I was bored! I let step-counting turn my fun, varied workout routine into something less fulfilling for me. Make your device the tool, don’t be the tool. 

    If competition or social comparison motivates you, consider tracking your activities with a device that shares your progress with others on a leaderboard. These groups help many people achieve their goals because they know people are watching. If you like working out with other people, let a virtual group get in the way of a real-life interaction. Use your device to find a workout buddy with similar interests, then go work out together! For example, go to a group class at the gym or compete in an actual competition such as a 5K. 
  4. Will my fitness tracker help me lose weight?  
    Step-counters have been shown to make people walk an average of 750 more steps per day (about a lap and a half around a 400 m track). That’s about 37 extra calories burned per day, which theoretically translates into about 2–4 pounds per year of weight loss. However, the evidence that fitness trackers promote weight-loss in the short term is mixed. This is likely because people feel they can eat more when they work out. 

    If you’re using an activity tracker to aid in weight loss, keep in mind that you can easily out-eat your calories burned. For example, a cookie has about 250 calories, which equates to about 5,000 steps. If you walk an extra 750 steps per day and eat a cookie as a reward for your hard work, you’re probably not going to lose weight. You can’t outrun a diet! 

    Many activity trackers also have built-in diet functions to help you track your daily food intake, calories, macros, etc. These apps can give you an idea of your caloric intake vs. calories burned to determine if you’re on track to meet your weight-loss goals. While it’s no magic bullet, a fitness tracker is a good tool to help you with your fitness goals. 
Bottom line

Fitness trackers can help you meet your goals, and you can start with the one built into your phone. Be sure to check out HPRC’s review of some popular options and pick one you and your wallet both like!

About the Author 
R. Max Lystrup, MD, is a board-certified family medicine/sports medicine physician who graduated from the Uniformed Services University in 2015. He completed his residency in 2018 in Family Medicine at Nellis Air Force Base, NV and his Sports Medicine fellowship at Fort Belvoir, Virginia. He’s authored multiple publications on activity trackers.

* The opinions and assertions expressed herein are those of the author and do not necessarily reflect the official policy or position of the Uniformed Services University of the Health Sciences or DoD. The contents of this publication are the sole responsibility of the author and do not necessarily reflect the views, opinions, or policies of The Henry M. Jackson Foundation for the Advancement of Military Medicine, Inc. Mention of trade names, commercial products, or organizations does not imply endorsement by the U.S. Government. The author has no financial interests or relationships to disclose.

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