Heart rate trekking between fitness enthusiasts is rapidly common, and makes sense. Whether it is a rugged outdoor smartwatch or a prudent smart ring, smart wearbals can help you determine if you have done enough exercise, resting well during sleep or have given a lot of emphasis during the day – just listening to your heartbeat.
some of the Best fitness trackers Even on the basis of how your health matrix can change over time, you can use machine learning to provide detailed exercise recommendations – not to mention that smart wareballs may be invaluable tools for endurance athletes. But how do fitness trackers measure your heart rate, of course? And how accurate are these measurements? We asked experts.
Most fitness clocks and smart rings depend on a technique called photoplethysmography (PPG). While its name can be the scarley complex, this technique is based on a relatively simple concept – light absorption by body tissues.
How does photoplethysmography work?
PPG uses optical sensors that detect heart rate By measuring the changes in the amount of blood flowing through small blood vessels and underlying connective tissue in the skin, Dr. Peter sogardProfessor and Chief Medical Officer of Cardiology at Aalborg University in Denmark VentricesA company that has developed a novel device to measure cardirespiratory fitness described live science by email.
With each heartbeat, Heart muscle Contracts to force and relax to force the next part of the blood in circulation. Contracting increases a temporary spike in blood volume and pressure on arterial walls, and is often referred to as a systolic phase of the heart cycle. When the heart relaxes between the beats, the blood flow decreases – it is known as a diastolic phase. PPG sensors measure these changes in blood volume and pulse pressure (difference between systolic and diastolic pressure), and then convert these matrix into heart rate measurement, Sogard said.
PPG sensors detect these changes in blood movement by emitting light on specific wavelengths in the skin. Blood components such as hemoglobin, protein in red blood cells, absorb some of that light. The tracker’s photodater then reflects the amount of light back. The more light the light is absorbed in the blood vessels, the more blood vessels have high volume – and it is what the fitness trackers interpret as a heartbeat, Sogard said.
“The most commonly used light sources are infrared and green LEDs,” Sogard said. This is because this wavelength of light is most effective in penetrating the tissues of the skin, according to the review of 2022, according to the review published. PhysiologyGenerally, the accuracy of PPG grows with light wavelength, the review authors said. Some optical sensors are also Mix several wavelengths to improve accuracy,
He is the principle. But how accurate are optical sensors in practice? The answer is less clear.
How correct is photoplethysmography?
“Many factors can affect the accuracy of PPG, tracker placement and body temperature to skin thickness, speed artifacts (deformities due to movement) and cardiovascular disorders Arrhythmia And peripheral vascular disease (a condition in which the arteries are blocked or compressed outside the brain and heart), ” Dr. Masaki NakamuraA cardiothoresic surgeon at the Baptist Health Miami Cardiac and Vascular Institute told live science by email.
For example, optical sensors provide more reliable heart rate measurements during comfort and sleep, as much as they do during exercise, according to 2020 meta-analysis Sports science journalScientists compiled 44 studies, which compared the accuracy of PPG fitness to more accurate ECG (electrocardiogram) and chest-strap heart rate monitor and found that the greatest discrepancies could be seen with weightlifting, cycling and other high-creating games. While most modern fitness trackers use accelerometer-based algorithms for rapid movements, motion artifacts may still affect their tracking accuracy.
Skin contact is another factor that can affect the PPG measurement, SOGAARD said. For example, a device that is very loose or too tight will not allow optical sensors to get a good reading. Skin temperature can also interfere with PPG. “If the patient’s temperature is low, Ships The contracted and the measurements go wrong, “Sogard said.
In addition, optical sensors can struggle with detecting heart rate in dark skin tones or tattoos. This is because both melanin, dark pigments in the skin, and tattoo ink can absorb light and reduce the amount of light reflecting the tracker back to the tracker, published according to a review of 2023. Racial and ethnic health inequalities journal,
Obese people can also struggle with obtaining accurate heart rate measurements. According to a review of 2021 published in the journal, body fat can lead to skin thickness and blood, ov, which is why it can affect the accuracy of optical sensors. biosensorsThe good news is that scientists are working on developing new techniques that will make PPG more accessible for these population groups.
PPG fitness trackers, according to Nakamura, may be useful for monitoring heart rate in some heart conditions. “Monitoring of continuous heart rate and blood pressure can be important for heart disease patients to prevent future events like a heart attack, Shock Or acute heart failure. The gold standard of blood pressure and heart rate assessment is the gold standard manual sphigmomometers (BP cuffs) and electrocardiograms. However, both these exams can only be measured and affected by such factors. White coat syndrome (A condition when a person’s blood pressure is high when measured in health care settings), caffeine or stress, “Nakamura said.
He said that experts believe that PPG-based heart rate reading should never be considered as an alternative to clinically valid tests conducted by healthcare professionals.
This article is only for informative purposes and does not mean to give medical advice.
