民间大测试：阿迪达斯等腕式心率监测仪真的精确无误吗？
We selected two testers to evaluate three wrist-worn cardiac monitors available on the market, converting the collected data into 24 charts. These charts provided us with first-hand insights into the performance of these devices. Can wrist-worn cardiac monitors truly deliver flawless accuracy? Can we really rest easy relying on them? The information gathered will help us answer these questions.
Smartwatches with built-in continuous heart rate monitoring have, unsurprisingly, sparked a frenzy among consumers this year. Traditional chest-strap monitors often become soaked in sweat after exercise, emitting an unpleasant odor. In contrast, wrist-worn smartwatch sensors take a different approach: by maintaining consistent contact with your wrist, they can accurately detect blood flow. This design is both convenient and ingenious. Furthermore, if your resting heart rate is gradually decreasing—a sign of improving fitness—the wrist-based monitor will detect this trend over time and notify you, potentially providing you with extra motivation.
But here lies the problem. Is the data obtained from this new type of wrist-worn monitor truly accurate and error-free? This issue warrants serious attention, because if the data are inaccurate, our daily exercise routines would be virtually meaningless.
☽☾ Why Do We Need a Detection Device with Precision Sensing?
The key to heart rate training lies in the fact that you cannot always train within a single heart rate zone; instead, you must train across different heart rate zones (a heart rate zone refers to the percentage of your current heart rate relative to your maximum heart rate; different heart rate zones during exercise correspond to varying physiological states and outcomes). Exercising in different heart rate zones activates distinct metabolic pathways, thereby influencing the quantity of enzymes in muscle tissue. Consequently, training in different zones exerts varied effects on the body.
Still unclear? Let me give you an example. The aerobic heart rate zone is generally between 70% and 80% of your maximum heart rate. Exercising within this range is commonly considered beneficial for strengthening cardiovascular and cerebrovascular health. You can estimate your maximum heart rate using a formula that only requires your age. However, the results obtained through this method can have significant margins of error. To determine your precise maximum heart rate, you could undergo professional testing; however, due to the cumbersome procedures involved in such tests, I do not particularly recommend it.
If you can monitor your heart rate zones in real time, you can tailor different workouts based on this data. If the real-time heart rate data provided by your monitor is accurate, such exercise can maximize your health benefits without overloading your body.
Chest-strap heart rate monitors have been on the market for some time. To obtain precise, real-time heart rate zone data, they capture the electrical signals transmitted through the cardiac muscle. According to tests conducted by fitness equipment brands such as Garmin, Polar, and Suunto, the data provided by this method is considered highly accurate. Therefore, chest-strap monitors enable users to train efficiently across different heart rate zones.
As for the accuracy of wrist-worn heart rate monitors, opinions remain divided.
☽☾How do manufacturers of wrist-worn heart rate monitors test the accuracy of their products?
Some mainstream companies, including the currently popular Mio, have publicly disclosed their accuracy tests for detection devices, with most results being positive. However, we found that the subjects of these tests were mostly not the detection devices themselves, but the sensors built into them. In other words, the sensors were removed from the detection devices and tested individually. The results of such tests are, of course, unreliable. Because in real-life scenarios, sensors are carefully housed within light- and vibration-free detection devices, the actual detection accuracy may not be as high as that observed in testing.
Furthermore, although most of these tests included assessments of running heart rate data, the running speeds selected during testing were significantly lower than those that users might actually achieve in real-world scenarios.
Worse still, apart from running, most of the heart rate data obtained from these tests were collected during walking or strolling, whereas most users rarely use the monitor to measure their heart rate while walking or strolling.
Based on the evidence we have found, the accuracy of wrist-worn heart rate monitors may be significantly compromised.
☽☾ A Major Test of Wrist-Worn and Chest-Strap Heart Rate Monitors!
Through these tests, we aim to determine just how impressive the latest wrist-worn smartwatches with heart rate monitoring capabilities on the market truly are. This experiment serves as a follow-up to the article “A Comprehensive Review of Single-User Wearable Devices.” In our proprietary testing survey, we will adhere to the criteria outlined in that article.
Are these monitors truly reliable in real-world scenarios? To find out, we designed a specific test. We selected two participants, each of whom wore both a wrist-worn monitor and a chest-strap monitor. It is important to note that the chest-strap heart rate monitors used by both participants in this trial had been verified as sufficiently accurate after a period of use; in other words, the data obtained from these chest-strap heart rate monitors are considered absolutely correct.
Why did we select two testers for the evaluation? Wouldn’t one have been sufficient? Our rationale was as follows: heart rates during running vary among individuals. By having the device measure a range of different heart rates, we aimed to verify its true accuracy.
Subject No. 1, namely the author myself, runs approximately 15–20 miles per week. Although I run at a slow pace, my heart rate increases significantly during exercise. This phenomenon is quite common in real-world scenarios, as even moderate running can elevate one’s heart rate to around 150 beats per minute, which is nearly exceeding the aerobic heart rate zone. During the experiment, I will wear three different wrist-worn monitoring devices, along with a Suunto chest-strap heart rate monitor (Ambit3 Run).
Subject No. 2 is Paul Radford, an ultramarathon runner (a long-distance running competition with distances exceeding the standard marathon distance of 42.195 kilometers). He has won five ultramarathon championships and broken four course records. However, he has not finished in the top ten since 2011. He runs approximately 80 miles per week, with an average heart rate of around 114 beats per minute during running. In the trial, he will use the Polar V800 chest-strap monitor as the control device for comparison.
Sean Radford, Paul’s younger brother, analyzes and studies the data obtained from our experiments. Sean is a physician and an avid runner. He is also the inventor of TrainAsOne, a running assistance device that allows users to upload data from their wearable devices to the platform. TrainAsOne then leverages this data to design personalized running training plans for each user; however, the system is currently still in the testing phase. Sean is highly proficient in evaluating exercise programs and can instantly determine whether a training plan is beneficial to a user. He has extensively reviewed medical reports and possesses thorough knowledge of most fitness equipment.
To increase the visibility of our experiments, we published our experimental charts in a journal. These charts were derived from our experimental data. The charts present various heart rate data sets, allowing readers to clearly observe discrepancies between the data obtained from wrist-worn monitors and chest-strap monitors.
Admittedly, our experiment lacks sufficient rigor. To scientifically investigate the differences between the two, a larger cohort of participants is required. Furthermore, to obtain more robust experimental results, it is essential to employ medical-grade equipment for data recording and to compare these findings with treadmill running data, among other measures. Although our study did not meet these stringent criteria, it did partially simulate real-world running conditions. Ultimately, we leave it to the readers to determine the validity of our experimental results.
▍Adidas miCoach Smart Run
The first wrist-worn device we tested was the Micoach smart RUN by Adidas. This wrist-worn device is slightly heavy and feels cumbersome on the wrist, with a white strap. Its overall design appears rather unremarkable. Although the display interface is somewhat cluttered, the large screen ensures that the information remains clear and easy to read at a glance.
Below are the advantages of this device. Like other wearables produced by Adidas, SmartRun features built-in continuous optical heart rate sensors manufactured by Mio. Liz Dickinson, CEO of Mio, has spoken highly of their sensor, praising it as a leader in its class and far more accurate than sensors used by devices such as Fitbit. Notably, Garmin’s first wrist-based heart rate monitor, the Forerunner 225, also incorporated this same sensor when it was first introduced. It is fair to say that this sensor has received widespread acclaim.
▍Garmin Forerunner 225
Following the completion of our experiments, we invited running enthusiast Kieran Alger to evaluate the Forerunner 225, a wrist-worn monitor equipped with MIo sensors. Kieran found that during testing, the heart rate data provided by the Forerunner 225 wrist-based heart rate monitor consistently differed from that of the Polar M400 chest-strap heart rate monitor by 3–5 beats per minute. This discrepancy is clearly visible in the chart.
Returning to the Smart Run, it proved to be highly accurate in recording my heart rate during running at an intensity of approximately 150 beats per minute (bpm). For the majority of the test duration (90% of the time), the Smart Run faithfully and accurately tracked my heart rate. Even when discrepancies occurred, the error remained within ±5 bpm, a margin negligible for practical purposes. Undoubtedly, wrist-based monitors with this level of precision can perfectly replace chest-strap heart rate monitors.
However, the Smart Run exhibited significant discrepancies when recording heart rates at Paul’s level (approximately 114 beats per minute). Although the Smart Run accurately recorded heart rate for the majority of the test duration (86% of the time), it occasionally displayed extreme deviations—occurring in roughly 1% of the test time—with errors spanning two heart rate zones. For a device specifically designed for running, such a degree of error can be considered a functional failure. Nevertheless, aside from these outliers, an average error rate of 10–14% is not excessive for casual runners and may suffice to persuade them to abandon chest straps in favor of wrist-based monitors. However, this level of accuracy remains far from adequate for runners with higher standards or those requiring precise measurements.
▍Basis Peak
The next wrist-worn device we tested was the Basis Peak. This device is highly versatile, capable of monitoring your heart rate not only during running but also every second of your daily life, including while you sleep. While aesthetic appeal is subjective, we found the design of this device to be rather unattractive and overall quite mediocre. Furthermore, possibly because the Basis Peak positions itself as an all-day heart rate monitor, the heart rate data it provides to runners during exercise is overly simplistic, lacking many key metrics that runners desire.
Basis stated that its monitor incorporates a specialized optical sensor with a unique operating mechanism, enabling continuous 24/7 heart rate monitoring. The company further claimed that the sensor was deployed only after passing internal testing, and that the test results would soon undergo third-party certification.
So, can the Basis Peak, equipped with this sensor, accurately record heart rate? The answer is: No. When recording my heart rate, the Basis Peak was accurate only 70% of the time, and there was a small probability (approximately 2% of the testing period) of data errors spanning up to two heart rate zones. Throughout the entire heart rate accuracy test, the device’s heart rate readings fluctuated continuously, averaging around 10 errors per minute.
However, the accuracy of the Basis Peak was somewhat unsatisfactory when testing Paul’s heart rate. Although the device took a considerable amount of time to detect that Paul was running, and the initial heart rate data had an error margin of 18 beats per minute. By the way, this device does not require you to manually start it before running; it features automatic detection capability, which can automatically sense your running activity and begin recording data. However, once the device detected that Paul was running, its accuracy improved. During 75% of the test period, the device accurately recorded Paul’s heart rate, with the error margin consistently maintained at around 5 beats per minute. Even so, neither Paul nor I were entirely satisfied, as we believed that this device still could not replace chest-strap heart rate monitors.
▍Fitbit Surge
Fitbit Surge is the last wrist-worn heart rate monitor we tested.
Among the three monitors we evaluated, this model boasts the most aesthetically pleasing design. However, it is not without flaws; its display screen is somewhat small, limiting the amount of information shown. This may make it difficult for runners to read the display while in motion. Although the device is simple to operate and user-friendly, it suffers from a persistent issue: its accuracy remains questionable.
This device utilizes Fitbit’s proprietary PurePulse technology for heart rate monitoring. Notably, the Fitbit Charge HR, currently regarded as the world’s premier wearable health tracker, also employs this same technology for heart rate detection. We had initially intended to use the Charge HR as the subject of this testing experiment; however, due to our inability to access its complete dataset, we were compelled to use the Fitbit Surge for this test instead.
How did the Surge perform? I had been running for nearly five minutes before it began recording my heart rate, and the results were less than ideal; it only captured accurate heart rate data 77% of the time.
When recording Paul’s heart rate data, the Surge performed slightly better than it did when recording mine. Although the device began logging data only eight minutes after Paul started running, the recorded data remained fairly accurate; for approximately 82% of the duration, the data captured by the Surge was precise and error-free.
☽☾ Is it still necessary to use a chest-strap monitor?
As previously stated, this trial was not a research study and therefore lacked rigorous methodology. To obtain more robust results, additional trials are required to validate our findings.Our conclusion is that the data accuracy of these three wrist-worn heart rate monitors is inferior to that of chest-strap heart rate monitors.Among these three devices, the Adidas miCoach with a built-in MIO sensor offers the highest accuracy; however, its recorded data still exhibits a 10% margin of error compared to chest-strap heart rate monitors.
Why is this the case? Why do these three wrist-worn monitors fall far short of chest-strap devices in terms of accuracy? Our experiments reveal the underlying reasons.One reason is that wrist-worn monitors seem ill-suited for measuring your heart rate while running.It measures heart rate significantly more accurately when you are not running or are jogging, compared to when you are running.
Why does this occur? We believe it is highly likely that arm swing during running affects the accuracy of wrist-worn monitors. Generally, the faster your running speed, the higher the frequency of your arm swing. If your arms swing too rapidly, the monitor on your wrist will constantly shift position, or the sensor may fail to clearly detect blood flow. Both scenarios can reduce the accuracy of heart rate data.
Another possibility is that the wrist-worn monitor is worn too tightly or too loosely. Although this issue may seem trivial, a slight deviation can lead to significant errors; during running, this problem can be greatly amplified. We may follow the instructions in the manual and wear the wrist-worn monitor correctly, but one oversight—fastening the strap too tightly or too loosely—could still affect accuracy.
The above represents our reasonable hypotheses regarding the poor accuracy of wrist-worn monitors. However, there is another point that warrants deeper reflection. Why did Paul and I exhibit different error margins when using the same wrist-worn monitor during testing? If the same device is used for measurement, shouldn’t the errors be identical? This is indeed a puzzling issue. We speculate that the discrepancy may stem from the difference in our average heart rates. Among the three devices tested, two—Fitbit and Basis Peak—delivered more accurate results for individuals with lower heart rates, such as Paul, whose average heart rate is lower than mine. In contrast, Adidas Micoach performed more accurately for individuals with higher heart rates, like myself. Additionally, differences in wrist morphology between Paul and me may have also contributed to these results.
As previously stated, if the detector is equipped with built-in sensors from MIO, the data recorded by the detector may be more accurate.
Our final verdict is that if you are determined to break free from chest-strap monitors and are indifferent to a 10–15% data error rate, the Adidas miCoach is undoubtedly your best choice. Additionally, the Garmin Forerunner 225, which uses similar sensors and was also tested by us, is worth considering.
If you are simply looking to purchase a running watch and are not concerned about the accuracy of its heart rate monitoring, then these three devices will meet your needs. During your runs, they can all provide roughly accurate heart rate data. However, if you require precise, real-time heart rate zone data to structure your training regimen, or if you are a perfectionist who demands highly accurate metrics, we would not recommend purchasing any of these three devices. Our researcher, Sean, ultimately concluded thatConsumers should remain skeptical of wrist-worn heart rate monitors, as he believes that current models on the market fail to meet the demands of professional runners.
In other words, for the time being at least, you’ll still need to strap on that stretchy, sweat-stinking chest-strap heart rate monitor when you go for a run.
Source: WAREABLE
Original Author: Shane Richmond
Compiled by Huang Ziming
Edited by | Mo Renying