Heart Rate Sensor

[Oliver Parkes]

PolarGrit X2 Pro Titan is a rough and rugged outdoor sports watch crafted for adventure with sapphire glass AMOLED display in titanium casing, and a hi-tech toolkit of navigation and performance features for exploring the wonders of the world, and the body.

Polar Grit X2 Pro is a rough and rugged outdoor sports watch crafted for adventure with sapphire crystal glass AMOLED display, and a hi-tech toolkit of navigation and performance features for exploring the wonders of the world, and the body.

An ensemble of biosensing instruments, AMOLED display, dual-frequency GPS, maps, and the most comprehensive suite of training and recovery tools on the market. The stage is set, and the Polar Vantage V3 smart sports watch is ready to put in the performance of a lifetime.

Polar Pacer Pro is an ultra-light, new-generation sports watch with integrated barometer that equips athletes with advanced tools to improve running economy, training sessions, and sports performance.

An all-round multisport & running GPS watch for anyone who loves setting new records. Polar Vantage M is a slim, lightweight training companion that gives you all the data you need to improve your performance.

Polar OH1+ is an optical heart rate monitor that combines versatility, comfort and simplicity. You can use it both as a standalone device and pair it with various fitness apps, sports watches and smart watches, thanks to Bluetooth and ANT+ connectivity.

A heart rate monitor (HRM) is a personal monitoring device that allows one to measure/display heart rate in real time or record the heart rate for later study. It is largely used to gather heart rate data while performing various types of physical exercise. Measuring electrical heart information is referred to as electrocardiography (ECG or EKG).

Medical heart rate monitoring used in hospitals is usually wired and usually multiple sensors are used. Portable medical units are referred to as a Holter monitor. Consumer heart rate monitors are designed for everyday use and do not use wires to connect.

Early models consisted of a monitoring box with a set of electrode leads which attached to the chest. The first wireless EKG heart rate monitor was invented in 1977 by Polar Electro as a training aid for the Finnish National Cross Country Ski team. As "intensity training" became a popular concept in athletic circles in the mid-80s, retail sales of wireless personal heart monitors started in 1983.[1]

Modern heart rate monitors commonly use one of two different methods to record heart signals (electrical and optical). Both types of signals can provide the same basic heart rate data, using fully automated algorithms to measure heart rate, such as the Pan-Tompkins algorithm.[2]

The electrical monitors consist of two elements: a monitor/transmitter, which is worn on a chest strap, and a receiver. When a heartbeat is detected, a radio signal is transmitted, which the receiver uses to display/determine the current heart rate. This signal can be a simple radio pulse or a unique coded signal from the chest strap (such as Bluetooth, ANT, or other low-power radio links). Newer technology prevents one user's receiver from using signals from other nearby transmitters (known as cross-talk interference) or eavesdropping. Note, the older Polar 5.1 kHz radio transmission technology is usable underwater. Both Bluetooth and Ant+ use the 2.4 GHz radio band, which cannot send signals underwater.

More recent devices use optics to measure heart rate by shining light from an LED through the skin and measuring how it scatters off blood vessels. In addition to measuring the heart rate, some devices using this technology are able to measure blood oxygen saturation (SpO2). Some recent optical sensors can also transmit data as mentioned above.

Newer devices such as cell phones or watches can be used to display and/or collect the information. Some devices can simultaneously monitor heart rate, oxygen saturation, and other parameters. These may include sensors such as accelerometers, gyroscopes, and GPS to detect speed, location and distance.[3] In recent years, it has been common for smartwatches to include heart rate monitors, which has greatly increased popularity.[4] Some smartwatches, smart bands and cell phones often use PPG sensors.[5]

The newer, wrist based heart rate monitors have achieved almost identical levels of accuracy as their chest strap counterparts with independent tests showing up to 95% accuracy, but sometimes more than 30% error can persist for several minutes.[9] Optical devices can be less accurate when used during vigorous activity,[10] or when used underwater.

Currently, heart rate variability is less available on optical devices.[11] Apple introduced HRV data collection to the Apple Watch devices in 2018.[12] Fitbit started offering HRV monitoring on their devices starting from the Fitbit Sense, released in 2020.[13]

Samson McDougall is a journalist, copywriter, editor and science graduate. Samson specializes in making the complex simple, using the English language to democratize knowledge through highly effective, accessible communication.

Rich Scherr is an updates strategist and fact checker for Dotdash Meredith brands, including Health and Verywell. He is a seasoned financial and technology journalist who served as editor-in-chief of the Potomac Tech Wire for nearly two decades, and is a regular contributor to the sports pages of The Baltimore Sun. He has also been a news editor for America Online and has contributed to the Associated Press and The Washington Post.

HR monitors come in two types, as George Sopko, MD, MPH, Medical Officer and Program Director of the National Heart, Lung, and Blood Institute (NHLBI) explains. Basic models check your HR range, while advanced models provide detailed heart rhythm information and can indicate potential cardiovascular issues.

Remember that even though some smartwatches can track your heart rate, they may not be as effective as a dedicated heart rate monitoring device. Experts say that the type of smartwatch you use can impact data reliability, especially during arm-intensive exercises, and accuracy can decline with higher activity levels or sweating.

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As wearable technologies are being increasingly used for clinical research and healthcare, it is critical to understand their accuracy and determine how measurement errors may affect research conclusions and impact healthcare decision-making. Accuracy of wearable technologies has been a hotly debated topic in both the research and popular science literature. Currently, wearable technology companies are responsible for assessing and reporting the accuracy of their products, but little information about the evaluation method is made publicly available. Heart rate measurements from wearables are derived from photoplethysmography (PPG), an optical method for measuring changes in blood volume under the skin. Potential inaccuracies in PPG stem from three major areas, includes (1) diverse skin types, (2) motion artifacts, and (3) signal crossover. To date, no study has systematically explored the accuracy of wearables across the full range of skin tones. Here, we explored heart rate and PPG data from consumer- and research-grade wearables under multiple circumstances to test whether and to what extent these inaccuracies exist. We saw no statistically significant difference in accuracy across skin tones, but we saw significant differences between devices, and between activity types, notably, that absolute error during activity was, on average, 30% higher than during rest. Our conclusions indicate that different wearables are all reasonably accurate at resting and prolonged elevated heart rate, but that differences exist between devices in responding to changes in activity. This has implications for researchers, clinicians, and consumers in drawing study conclusions, combining study results, and making health-related decisions using these devices.

Wearable technology has the potential to transform healthcare and healthcare research by enabling accessible, continuous, and longitudinal health monitoring. With the number of chronically ill patients and health system utilization in the US at an all-time high,1,2 the development of low-cost, convenient, and accurate health technologies is increasingly sought after to promote health as well as improve research and healthcare capabilities. It is expected that 121 million Americans will use wearable devices by 2021.3 The ubiquity of wearable technology provides an opportunity to revolutionize health care, particularly in communities with traditionally limited healthcare access.

The growing interest in using wearable technologies for clinical and research applications has accelerated the development of research-grade wearables to meet the needs of biomedical researchers for clinical research and digital biomarker development.4 Consumer-grade wearables, in contrast to research-grade wearables, are designed, developed, and marketed to consumers for personal use. While research- and consumer-grade wearables often contain the same sensors and are quite similar functionally, their markets and use cases are different, which may influence accuracy (Supplementary Table 1). Digital biomarkers are digitally collected data that are transformed into indicators of health outcomes. Digital biomarkers are expected to enable actionable health insights in real time and outside of the clinic. Both consumer- and research-grade wearables are frequently being used in research, with the most common brands being Fitbit (PubMed: 476 studies, ClinicalTrials.gov: 449 studies) for consumer-grade wearables and Empatica (PubMed: 22 studies, ClinicalTrials.gov: 22 studies) for research-grade wearables (Supplementary Table 2).

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