The Fitbit Flex. Photo via Wikimedia Commons.
The Nike Fuel Band in action. Photo via Wikimedia Commons/IntellFreePress.

The Nike Fuel Band in action. Photo via Wikimedia Commons/IntellFreePress.

Technology used to be something external, we traveled to the office to use it – you sat  at your computer. Then technology became something we carried around – our cellphones, our laptops. Wearable tech used to be something of sci-fi and comic books – but now it is the norm. Among the most popular form of wearable technology is the fitness tracker. The old-school pedometer seems like an obsolete dinosaur next to the Jawbone, Fitbit, Nike Fuel Band and soon-to-arrive Apple Watch, which all sync data to your computer or phone, and give real-time measurements of steps taken, miles walked and calories burned.

Among fitness products, Fitbit is well in the lead for sales and hype – accounting for over 50% of the three million plus sales of wearable fitness devices across a one-year period in 2013 and 2014, and sales increasing at a breakneck speed. I can count myself among one of those sales, when I strapped the Fitbit Flex onto my wrist back in June of 2013. I was intrigued by the promise that the Fitbit would monitor my sleep and motivate me to exercise more.

Fitbit’s mantra is to make fitness part of your daily routine, allowing you to track your own data and use social media to “challenge” friends to meet their exercise goals. Fitbit has tapped into our need to be constantly connected by giving you live data – on your wrist – of how much you have walked each day. When you meet your daily goal, the Fitbit lets you know with a strong vibrating buzz. Not knowing exactly when that buzz is coming is like the variable reinforcement schedule that makes gambling so powerful.

From my own experience (and the testimonials of many others on the internet), the Fitbit can inspire you to exercise more to meet your daily goals (the default is 10,000 steps per day, but you can increase or decrease that amount if you choose). I know there have been times that I have marched in place before bedtime (apparently I am not alone), or walked somewhere instead of biking to tally some steps and get that rewarding buzz telling me, “goal achieved.”

Can fitness trackers increase activity levels? Photo via WIkimedia Commons/Kyle Cassidy.

Can fitness trackers increase activity levels? Photo via WIkimedia Commons/Kyle Cassidy.

But is this a trend that will last? Sixteen months later, I still love my Fitbit. But are these fitness devices actually helpful for the (perhaps less exercise-obsessed) general public? By being aware of how much (or how little) you are exercising, can the Fitbit motivate you exercise more? And perhaps more importantly, how well do fitness trackers work? Is the information (steps, distance, calories) even accurate?

As relatively new devices, there has not been a huge amount of scientific (published) research on many of these fitness trackers, but there a few recent studies exist (particularly on some of Fitbit’s older models, such as the One and the Zip). Let’s see what the science says about the reliability and efficacy of the Fitbit.

First of all, are they accurate? Do Fitbits measure what they claim to?  Research suggests that for some measures, yes. All models of Fitbits tested showed high accuracy when it came to the number of steps taken. One study had folks wear a Fitbit and a research-grade accelerometer, the Acti-Graph, while walking on a treadmill. The Fitbit showed high correlation with steps recorded by the ActiGraph. A comparison with the Yamax, the “Gold Standard” pedometer, also showed high accuracy of the Fitbit even when people took just 20 steps. Another study found a high validity, with resulting step count by the Fitbit being within 9% of the actual steps taken, unless the accelerometer was placed in a pocket, in which case accuracy was significantly decreased. This decrease in accuracy in the pocket was especially strong at high running speeds (greater than 8 km/hour).

Fitbit’s accuracy for distance travelled was not as impressive. In general, Fitbit output did not match treadmill output, but this effect was also dependent on speed. One study found that the faster the walking speed, the greater the error for the distance measure. This may be in part due to the fact that unless you specify a stride length in your Fitbit account, Fitbit picks a default for you based on your height.

Fitbit thinks you're burning a lot of calories when you carry groceries. Photo via Shutterstock.

Fitbit thinks you’re burning a lot of calories when you carry groceries. Photo via Shutterstock.

For measuring overall activity level, Fitbit is also a little shaky. In order to measure calories burned, participants are typically hooked up to a metabolic analyzer, a device that has a mouthpiece and accurately determines how many calories you are burning by measuring the oxygen you are consuming. While the Fitbit doesn’t think you’re doing much when you’re not doing anything physical (e.g. riding in a car), the device did tend to underestimate the amount of energy expended (EE) during certain activities, such as cycling and doing laundry, and overestimated energy expended for others (apparently carrying groceries is a real Fitbit-fooler). Another study found that the Fitbit underestimated EE during brisk walking, but was more accurate at slow speeds. Yet another study, of folks in their 60s, also found that the Fitbit underestimated calories burned. That said the two models of the Fitbit had a lower error rate compared to both the Jawbone Up and Nike Fuel Band when it came to measuring caloric expenditures.

So when it comes to accurately measuring your activity, it appears that Fitbit is good for counting steps, might need some help when it comes to measuring distance, and is not particularly reliable for counting calories burned. But for the Fitbit to be useful, accuracy isn’t enough. You have to actually use it. Do people stick with their Fitbit? And does the Fitbit motivate them to exercise more?

Personalized feedback is highly motivating.

Personalized feedback is highly motivating.

While there are plenty of online testimonials of a loving, long-term relationship between an owner and their Fitbit, there are few studies, especially longitudinal studies, to examine whether people who start using a fitness tracker stick with it. One study determined that “success” was dependent on the level of self-monitoring and engagement with the Fitbit website (which suggests that maybe people who are more likely to use a Fitbit in the first place are already more motivated to track their activity). A longitudinal study found that 28% of participants lost their Fitbits, and another 32% reported technical difficulties with the Fitbit or website that made it difficult to collect complete data.

A recent study of how technology can motivate people to increase fitness suggests that some features of the Fitbit may be more motivating than others. Reasonable goal-setting was critical to engagement, including allowing primary goals (such as steps per day) and secondary goals (steps per week). Participants who received reminders to exercise reported being more likely to follow through, but the reminders had to be specific to the individual’s goals, not just “hey, exercise more today!” Receiving virtual rewards (such as ribbons and badges) was not motivating, and participants found them gimmicky. People were also hesitant to share their exercise reports via social networks due to embarrassment or fear of boring people with posts about their exercise goals.

2011 Obesity Map of the United States, courtesy of Wikimedia Commons/Falcorian.

2011 Obesity Map of the United States, courtesy of Wikimedia Commons/Falcorian.

Encouraging people to maintain healthy habits is a challenge that pre-dates technology. Fitness trackers allow people to track progress in the form of short-term goals (such as number of steps walked per day) before they reach some longer, more difficult goals (such as weight loss); achieving short-term goals might help people stick to their exercise routines. The live-time feedback from devices like the Fitbit allows individualized feedback, which may be key to motivation. But will we become a Fitbit nation or continue down a path toward nationwide obesity? We probably need a few more years to find out.

 

References:

Aarts, H., Paulussen, T., & Schaalma, H. (1997). Physical exercise habit: on the conceptualization and formation of habitual health behaviours. Health education research12(3), 363-374.

Gusmer, R. J., Bosch, T. A., Watkins, A. N., Ostrem, J. D., & Dengel, D. R. (2014). Comparison of FitBit® Ultra to ActiGraph™ GT1M for Assessment of Physical Activity in Young Adults During Treadmill Walking. Open Sports Medicine Journal8, 11-15.

Harrison, D., Berthouze, N., Marshall, P., & Bird, J. (2014, September). Tracking physical activity: problems related to running longitudinal studies with commercial devices. In Proceedings of the 2014 ACM International Joint Conference on Pervasive and Ubiquitous Computing: Adjunct Publication (pp. 699-702). ACM.

Lee, J. M., Kim, Y., & Welk, G. J. (2014). Validity of Consumer-Based Physical Activity Monitors. Medicine and science in sports and exercise.

Mammen, G., Gardiner, S., Senthinathan, A., McClemont, L., Stone, M., & Faulkner, G. (2012). Is this Bit Fit? Measuring the Quality of the Fitbit Step-Counter. The Health & Fitness Journal of Canada5(4), 30-39.

Munson, S. A., & Consolvo, S. (2012, May). Exploring goal-setting, rewards, self-monitoring, and sharing to motivate physical activity. In Pervasive Computing Technologies for Healthcare (PervasiveHealth), 2012 6th International Conference on (pp. 25-32). IEEE.

Phillips, E. M., Schneider, J. C., & Mercer, G. R. (2004). Motivating elders to initiate and maintain exercise. Archives of physical medicine and rehabilitation,85, 52-57.

Sasaki, J. E., Hickey, A., Mavilia, M., Tedesco, J., John, D., Kozey, K. S., & Freedson, P. S. (2014). Validation of the Fitbit Wireless Activity Tracker® for Prediction of Energy Expenditure. Journal of physical activity & health.

Takacs, J., Pollock, C. L., Guenther, J. R., Bahar, M., Napier, C., & Hunt, M. A. (2013). Validation of the Fitbit One activity monitor device during treadmill walking. Journal of Science and Medicine in Sport.

Wang, J. B. (2014). A Wearable Sensor (Fitbit One) and Text-Messaging to Promote Physical Activity and Participants’ Level of Engagement (A Randomized Controlled Feasibility Trial) (Doctoral dissertation, University of California, San Diego).

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57 comments

  1. Pingback: How fit is that Fitbit? | cats and squirrels and other important things...

  2. Bonnie

    Great summary!

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  6. Hannah

    “How Fit is that Fitbit?” is an article where Mikel Delgado asks the questions, “Is the Fitbit a trend that will last or fade away?” and, “Will it actually help you to stay fit?”. Delgado provides research about how accurate the Fitbit is, as well as a description of how it is designed to motivate people to workout. He explains that the short-term goals of steps taken per day help lead people to accomplish long-term goals and “may be the key to motivation”. However, like many other technologies today, I see how the Fitbit could have a negative impact. Delgado himself says, “(The) Fitbit has tapped into our need to be constantly connected by giving you live data – on your wrist – of how much you have walked each day”. While the technology we have is a great gift that has given us many opportunities and benefits, some technology when used improperly, have in fact hurt more than helped us.
    I think the question that needs to be asked is, “What is our focus?”. I myself have a Fitbit, and found that although it was motivating, it also made me place too great of a focus on fitness. Until I had a Fitbit, I never ended a day being disappointed because I had not taken 10,000 steps. The fact that many people, including Delgado, admit that “there have been times that they have marched in place before bedtime” show that there is a misguided view of how to use this technology. While the Fitbit can be of use, I think it can lead to an unhealthy focus on fitness and, as a result, on people’s looks. If people are only looking for their 10,000 steps (which does not truly indicate one’s fitness) or if they only want to be fit because they believe their worth lies in how fit they are, then I think the Fitbit can be harmful. It’s live data feature also continues to condition us for immediate answers and results when in fact most things in life are not immediate. Things in life take time and effort, including fitness. This is not to say that the Fitbit is bad. For some people it might just be the push they need to get in shape. However, it is important to realize the effects different technologies can have on our lives.

    -4
    • t rollings

      People who argue that others are trying to just look better by being fit are usually not that attractive, don’t be that ugly girl Hannah

  7. Annette

    I love my fitbit! I use it to log exercise and calories, but more important, I am using it as a tool for behavior modification. I have almost reached my weight loss goal and I am thinking ahead to maintenance. The daily reminder of how many calories it takes to maintain a current weight is a powerful counter message to our “all you can eat” culture. It really keeps me mindful.

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  12. Ian

    Fitbit opened my eyes to how in- active my life was. Going to the office and then resting after a hard day, is not good for me. We hear recommendations that we do X amount of activity a day and fit bit shows me I am well below this.
    I was never really aware of the calories I ate every day, fit bit shows me what I’ve consumed and what I’ve burnt.
    Fitbit is not 100% but give it time and development and I believe this could benefit all of us.

  13. John Begley

    Really good summary.
    A mantra in business is “If you don’t measure it, you can’t manage it”. I have found the Fitbit very helpful in my quest to change some of the habits that are causing me to be unhealthy. And I agree with many of the points here: badges gimmicky; calories burned shaky; don’t publish on social media as its adding to the damaging filtered self-marketing trend etc. But, all in all, I believe that the trend for a more intelligent approach to improve the nations health by recognizing that the key is to modify habits and motivations is going to prove more helpful than previous attempts… well, at least, I hope so.

  14. dule

    These studies only look at trackers that count steps. The better trackers also monitor heart rate, which I imagine would get you much closer on the calorie count. I’d be interested to know if there were any studies into these trackers.

    • Mikel Delgado

      Dule, I think some of these products are relatively new, so I would guess as time passes, there will be more studies, including with ones that record multiple measures of activity.

  15. Mikel Delgado

    Annette, Joh, and Ian, I agree with you. The Fitbit has increased my awareness of my daily activity levels, and I think they can be helpful. As time passes, I have become less “obsessed” with meeting goals, I’m just using the Fitbit as a motivator when I can!

  16. Tadgh78

    Can the fitbit tell you how fit you are?

    • Mikel Delgado

      The fitbit can really only tell how much you are moving…not how fit you are!

      • Karina

        BUT! I agree, it can only tell you how much you are moving. In my particular case, it came at just the right moment in my fitness psyche. I became aware of my level of inactivity and discovered how incredibly competitive I am with myself.

        As a direct result of purchasing my Fitbit Zip in mid-March, I have lost 34 pounds (most from May through July), I have taken up starting to run and my stamina has improved to a level it hasn’t been in decades since I had moved from a city environment to a suburban one.

        The habits I began as a part of having the fitbit are reasonably ingrained at this point. Maybe once they are a complete and total part of my being, *maybe* I won’t weird out if I go a couple hours without my little critter, but right now, that grinning potato guy has given me so much.

  17. Marc

    intereating and helpful. I would just point out that, to the extent that Fitbit tends to underestimate certain values, e.g., calories burned, that does not make it less useful for weight loss and fitness. My principal concern is that I will be misled if the Fitbit is too generous. Also, it seems to me that any sensible user would assume that Fitbit data are merely good-enough approximations–but good enough to help you meet your goals over time. My guess is that anyone who becomes frustrated by the kind of inaccuracy levels reported here is looking for an excuse. Why do I think so? Because I have been looking for excuses for 40 years, and blaming your tools is one of the best.

  18. mike

    In another article people are complaining because the fitbit told them they can eat “xxxx” amount of calories, which is absurd to think about. Within 2 days my fitbit had me researching average calories burned for someone my size & the way different carbs are processed throughout the body (I enter every meal and slightly overestimate to cheat to the positive). As a few comments alluded to, just a little thought and understanding of how this works and can help goes along way. For example, I started taking mine off when Im at my desk so it doesnt interpret certain hand movements as steps; after noticing it added 20 steps while standing still washing my hands.

    I starting using on a Monday and by Friday already felt slimmer because it made me aware of what I was or wasnt doing properly.

    -2
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  20. Michael

    Mikel,
    I was thinking of using fitbit to try to track activity of some subjects. The two attributes that I’m a bit more interested in are: 1) posture – time spent sitting and laying down versus standing/walking, and 2) longitudinal tracking – getting the activity data out to follow the same subjects over several months. I’d enjoy talking with you more if you have any helpful thoughts on these. Please feel free to email me.
    Yours, Michael

    • Mikel Delgado

      Michael,
      Your research sounds interesting, and you could possibly get current users to sign up for such a study. I have to admit, that aside from being a user and doing a little research for this article, I am no expert on movement tracking/physiological research…you might even want to contact the fitbit folks!

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  25. Anonymous

    Nice article! Really useful! I really liked it!

  26. Anonymous

    I rely heavily on my elliptical machine and I’m religious to it, but I’m not so diligent about other forms of fitness, my diet, or sleep patterns. I had a pin pedometer, but it was extremely dependent on my clothes IE extremely inaccurate. Id like to get the Fitbit to remind me of my health when I’m not on a cardio machine, to get a general idea of my heart rate during fitness routines, and for the social aspects of community fitness goals.

    I’ve read online that the battery life is about 48-60 hours and takes roughly 2 hours to charge. When do you charge it if you wear it in your sleep? They should come with a basic step monitor for when it’s charging. I also read about a lawsuit regarding inacurate heart rate measurements, but I don’t expect 100% accurate readings…well, maybe I do for that price.

    Fitbit is rather expensive imo, especially for a beta market. $100-$300 seems like a lot of money to pay for generalized personal data. I feel like this company is intentionally misleading consumers to believe that this is a medical device when it’s about as medically reliable as a diet pill.

    I’m not sure I’m ready to jump on the Fitbit bandwagon just yet. If I could get one for $50-$70, Id buy it. I’m looking for promotions, contests, coupons, discounts, and trials right now. Unfortunately, I’m getting a lot of the spam that comes with the free iPhone bs. I wish I could earn one by getting lower payments for reaching a goal – yeah right. This is the kind of stuff that makes me feel poor. Perhaps I can find a refurbished flex or HR once the fad dies down. I’m definitely not eager to spend about $200 on something that could help as much as my elliptical or end up on the dresser beside my pedometer.

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