Hey there, and welcome to my weekly summary of research from the world of sports science.
This week’s studies cover all things wearable devices, including their accuracy for tracking data about your steps, energy expenditure, heart rate, sleep and more—read on!
The Reliability of Wearable Devices for Measuring Steps, Energy Expenditure and Heart Rate
This study reviewed the accuracy and reliability of popular wearable devices, such as Fitbit, Apple Watch and Garmin, in measuring step count, heart rate and energy expenditure. The review included 158 studies and found that most devices accurately tracked steps in laboratory settings, with Fitbit, Apple Watch and Samsung performing well. Heart rate accuracy varied, with Apple Watch and Garmin being the most reliable, while Fitbit often underestimated. However, no device was accurate in measuring energy expenditure. As wearables are frequently updated, the study emphasizes the need for ongoing research to evaluate new models.
My thoughts: Fitness trackers aren't too accurate for things like energy expenditure or step count (and they are for the easier things to measure, like heart rate). What's interesting though, is that they all gathered similar results. So, here's a question: do they need to be accurate, or are the changes in data what matter? If you double your step count, surely you're doubling your level of activity, even if the actual steps measured aren’t accurate.
The Accuracy of 3 Popular Wearable Devices for Sleep Tracking
This study systematically reviewed the accuracy of three popular wearable devices—Fitbit Charge 4, Garmin Vivosmart 4, and WHOOP—in tracking sleep compared to the gold-standard method, polysomnography (PSG). While PSG is highly accurate, it's expensive and inconvenient for long-term use, making wearables a potential alternative. The review found that WHOOP performed best for tracking total sleep time, light sleep and deep sleep but struggled with REM sleep accuracy. Fitbit Charge 4 showed the highest accuracy for REM sleep and performed better than Garmin Vivosmart 4 overall. However, all devices had room for improvement in tracking specific sleep stages. The study highlights the need for more research to improve the accuracy of these devices and suggests future studies should use standardized methods with larger sample sizes.
My thoughts: Wearables provide a reasonable picture of your sleep, but don't get too carried away with the data just yet. Consider them to be about 80% accurate and take the data with a grain of salt—they’re not perfect.
The Accuracy of Wearable Technology in Health Measurement
This study explored the accuracy of consumer wearable devices in measuring health metrics like heart rate, sleep and physical activity. Analyzing 24 systematic reviews involving nearly half a million participants, the study found that while wearables generally performed well for heart rate and arrhythmia detection, they overestimated aerobic capacity (VO2max) and had significant errors in measuring physical activity intensity, step counts and energy expenditure. Sleep tracking tended to overestimate total sleep time. Overall, only a small percentage of wearables have been fully validated for accuracy, highlighting the need for more standardized research and collaboration to improve the reliability of these devices.
My thoughts: Wearable technology is getting better and more accurate. This has caught the eye of the healthcare industry, and almost all the studies I read from this last year have focused on their use to detect, monitor, or help prevent the development of certain health conditions. Wearables aren't a flash in the pan. They'll be "implanted" in our lives in no time at all. For us athletes, this is great news as healthcare has deep pockets to invest in and continue the progress toward accurate, real-time monitoring of our physiology.
That’s all for this week! If you learned something new and are curious to know more, head over to the Blonyx Blog or my growing list of weekly research summaries where I help you further improve your athletic performance by keeping you up to date on the latest findings from the world of sports science.
– Train hard!
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