Do you need a wearable health & fitness tracker?

Getting on track

Overwhelming evidence indicates three lifestyle choices can help humans optimize wellness: increasing physical activity behaviors, decreasing sedentary behaviors, and consuming a well-balanced diet.

As director of the University Weight Control Center for more than 12 years, I supported the use of “structured lifestyle interventions” to increase participation in physical activities. This included group or individual counseling, introduction of behavior change and self-monitoring techniques, written information, and phone/online counseling.

Our program proved effective for changing behaviors, as long as people were enrolled. When the 12-week program concluded, nearly half of the participants did not maintain their newly learned exercise/nutrition behaviors during a one-year follow-up. Those participants reported it was too difficult to “do it on their own.” They needed continuous interaction, support, reminders, hints, and to-do lists. On a positive note, 50% of the participants (approximately) reported “success” at maintaining their new behaviors at the same one-year follow-up.

What are you wearing?

Consumer-based health/fitness wearables can help one feel they are not doing this “on their own.” Wearables can monitor physical activity and specific health metrics and, when combined with a smartphone or computer, assist with a range of other motivational and health-monitoring tools. It’s just like the activities we performed in the clinic but with less expense. These tools include continuous heart monitoring with the diagnostic ability to detect rate and function abnormalities, blood oxygen saturation (PO2), sleep tracking, body temperature, blood pressure, and even blood glucose levels. These emerging technologies can provide ongoing support and motivation and interface with designated medical professionals.

The health & fitness wearable marketplace will be worth an estimated $63.48 billion by 2027! Wow! Rising health awareness is a vital factor in increasing this market growth.

What can fitness/health wearables measure?

Step counter/exercise trackers
Most wearable health/fitness devices include some sort of step counter that records how many steps and distances are covered for a given period. Prudent recommendations include a minimum of 7,000-10,000 steps daily to decrease sedentary risk syndrome (cardiovascular disease development). Most current wearable health/fitness devices also monitor acceleration, frequency, duration, intensity, and movement patterns. Some devices allow users to add running, cardio, dancing, cycling, and more. Summary information and recommendations data are available on request.

Vital sign monitor
Most modern wearables can track vital signs, such as resting and activity pulse rate, and make comparisons with individuals of one’s same gender and age, reflecting changes (improvements) over time. Some devices offer selected body temperature readings, perspiration tracking, blood-oxygen saturation, and menstrual cycle data. By combining physical and workout data, the user can get a better picture of their overall health. Moreover, these data also can be stored and forwarded to an individual’s physician.

There are roughly 32,000 gyms in the U.S. with about 64 million people who regularly exercise in them. Of these, about 55% use a smartwatch to track their exercise duration, heart rate, steps, distance, and more. (Image: iStock.)

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Sleep recorder
Keeping track of how much and how restful one sleeps is an important metric that offers important insight into health. Some trackers can discern and distinguish between sleep cycles, including REM sleep. Sleep quantity and quality represent an important indicator of health and wellness. In a previous column, I discussed different aspects of sleep and health.

Calorie tracking
Most health & fitness wearables can track the number of calories expended during rest and physical activity; some allow the user to track calories consumed by entering the foods consumed.

Sync with other devices
All health & fitness wearables can work with applications installed on a phone, tablet, or computer. Users can store data and compare progress with others (or just oneself) day-by-day or week-by-week. Some wearable devices are compatible with other tools, such as smart scales and clocks, or even specific exercise equipment. In some instances, one can instantaneously transfer data to a physician for review and evaluation. A growing number of devices can produce a medical-quality ECG (electrocardiogram) that offers a cursory evaluation of some heart anomalies and conditions like atrial fibrillation (AF), bradycardia, or tachycardia. These conditions may warrant further evaluation by a physician.

Expectations

Before you go out and buy a fitness/health tracker, make sure it’s worth it to you. Here are some of the pros and cons to consider.

Emerging technologies can provide ongoing support and motivation and interface with designated medical professionals. (Image credit: iStock.)

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Pros
For many, tracking different fitness/health metrics can provide a better understanding of how you’re doing, not how you think you’re doing. This is important. Properly used, wearable data can provide the first indicator that something has gone haywire healthwise, and offers the opportunity to be proactive, not blindsided by an unwanted diagnosis.

Also, trackers can be very motivating, particularly to those who like numbers, notifications, digital rewards, comparisons, and reminders. When it’s cold outside, going for a winter walk may be a non-starter for many, but a simple reminder from a tracker may motivate one to produce enough steps to reach the day’s goal. The trackers feed into our competitive nature, pushing us toward the finish line, even when difficult.

Cons
Not all fitness trackers are created equal. They have varying degrees of accuracy. Research indicates most trackers are reasonably accurate, but ‘reasonably’ isn’t perfect, which always leaves room for error. How much error depends on which device you choose. Inaccuracies can range from +/- 3% up to 20%. And another consideration is repeatability: Can the monitor accurately produce the same result on the same person on repeat use within a few minutes?

Any new gadget is fun for a while, and wearable trackers are no different. After some time, many individuals find themselves bored and over-stimulated with data, not to mention the need to constantly input and update data. The process can become anxiety-provoking, particularly for those who become obsessed with amassing the most data possible.

Another negative aspect is cost. There’s a tracker for every budget and style; you can spend $50, $1,000, or more. As with any technology, the more you spend, the more you get.

Let’s talk about accuracy

Scientists have done numerous validation studies on most mainstream health & fitness trackers. The results indicate that accuracy is variable, depending on the technology used and what the tracker is trying to measure.

Any fitness tracker needs to accurately assess your activity level to be able to calculate it. A recent research review of the latest health & fitness trackers found that wrist- or arm-worn trackers for measuring energy expenditure varied in accuracy, depending on the task being performed. When the body’s movement was the only parameter being measured, they were less accurate than when the tracker also included a heart-rate monitor or body-heat sensor. In another study measuring aerobic workouts, caloric expenditure tended to be overestimated when working at a slower pace and underestimated when working at a faster pace.

Yet, in another study that compared 11 different trackers, researchers found that accuracy varied between them when counting steps. They tended to be better at correctly counting steps during brisk walking than day-to-day activities and intermittent walking when arm movements were frequently miscounted as steps.

Earlier-generation fitness trackers came with a chest band to measure heart rate by tracking the body’s electrical signals. These devices are very accurate. In contrast, modern fitness trackers worn on the wrist that measure heart rate using photoplethysmography (PPG) are less accurate, by varying degrees, depending on the tracker. These trackers contain LEDs (light-emitting diodes) that send light waves into your skin, and a photodetector captures the light that bounces off the wrist, which is then turned into information that the device’s inbuilt algorithms can analyze to determine heart rate. While these trackers have been shown to be accurate enough for measuring the heart rate of an average person, they are not suitable for research purposes and tend to produce erroneous, extreme readings, which might misinterpret the real-time exercise intensity.

Conclusions

Overall, the research on fitness & health trackers indicates that most people who use them tend to become more active, increase their step counts, and expend more energy at moderate and vigorous levels. They also found that trackers helped maintain good habits in the long term and could be helpful to medical professionals monitoring the health of their patients.
 
 
References

• ACSM. Wearable technology named top fitness trend for 2024.
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• Chevance, G., et al. “Accuracy and precision of energy expenditure, heart rate, and steps measured by combined-sensing Fitbits against reference measures: Systematic review and meta-analysis.” JMIR mHealth and uHealth. 2022;10(4): e35626.
• Fuller, D., et al. “Reliability and validity of commercially available wearable devices for measuring steps, energy expenditure, and heart rate: Systematic review. JMIR mHealth uHealth. 2020;8(9): e18694.
• Gualtieri, L., et al. “Can a free wearable activity tracker change behavior? The impact of trackers on adults in a physician-led wellness group.” JMIR Research Protocols. 2016;5(4): e237.
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• Molina-Garcia, P., et al. “Validity of estimating the maximal oxygen consumption by consumer wearables: A systematic review with meta-analysis and expert statement of the INTERLIVE network.” Sports Medicine. 2022;52(7):1577–97.
• Perez, M.V., et al. “Large-scale assessment of a smartwatch to identify atrial fibrillation.” New England Journal of Medicine. 2019;381(20):1909–17.
• Piwek, L., et al. “The rise of consumer health wearables: Promises and barriers.” PLOS Medicine. 2016;13(2): e1001953.
• Shilaih, M., et al. “Modern fertility awareness methods: Wrist wearables capture the changes in temperature associated with the menstrual cycle.” Biosci Reports. 2018;38(6): BSR20171279.
• Spaccarotella, C., et al. “Assessment of non-invasive measurements of oxygen saturation and heart rate with an Apple Smartwatch: C0mparison with a standard pulse oximeter.” Journal of Clinical Medicine. 2022;11(6):1467.
• Swee Sun Tang, M., et al. “Effectiveness of wearable trackers on physical activity in healthy adults: Systematic review and meta-analysis of randomized controlled trials.” JMIR mHealth uHealth 2020;8(7);e15576.

Lead image: iStock.)