At present, there are two main methods for monitoring the heart rate of the smart bracelet, one is the photoelectric transmission measurement method, and the other is the ECG signal measurement method. The so-called photoelectric transmission measurement method simply means that the regular beat of the heart will cause the change of blood light transmittance. Collecting this change information and converting it into an electrical signal corresponds to the heart rate information. There is a generator and a photosensitive receiver at the end of the bracelet that contacts the skin. When the generator irradiates a beam of a certain wavelength on the skin surface, the beam will return to the photosensitive receiver through transmission or reflection. During this process, the beam is affected by the wrist The absorption and attenuation of skin muscle tissue and blood, the intensity of light detected by the detector will be weakened.
Among them, the absorption of light by the skin and muscle tissue remains constant throughout the blood circulation, and the blood content in the skin will change regularly under the action of the heart pumping blood. When the heart contracts, the blood volume is the largest, and the light absorption reaches the maximum. At this time, the detected light intensity is the smallest. On the contrary, when the heart is dilated, the detected light intensity is the largest, so that the light intensity received by the light receiver is followed. Pulsatile changes.
The second method is the ECG signal measurement method. This method is similar to the ECG detection commonly used in hospitals, but the smart bracelet only needs to detect the heart rate data, and the complexity is lower. In each heart cycle of the human heart, the atria and ventricles are excited successively, accompanied by the successive actions of countless cardiomyocytes, which will cause potential changes. These changes in bioelectricity are called ECG. By detecting the periodic changes of ECG Heart rate can be detected. Every time a heartbeat occurs, there will be tiny electrode changes on the person’s body surface. The smart bracelet captures these electrode changes, and then the algorithm can restore the frequency of the heart rate beat, and then real-time monitoring of the heart rate can be achieved.
Heart rate (HR) and heart rate variability (HRV) have received a lot of attention recently.
However, both of these indicators have many advantages and disadvantages and should be considered before using one of them. In order to determine when to use these two indicators correctly, it is important to understand the basic science behind each indicator.
What is the difference between HR and HRV?
Heart rate (HR) is measured in beats per minute. It does not require an exact time, it is just the average of the beats in a specific time period. Generally, low HR means rest, while high HR means exercise. Heart rate is concerned with the average number of heartbeats per minute, while heart rate variability (HRV) measures the specific change in time (or variability) between consecutive heart beats. The time between beats is in milliseconds (ms) and is called “R-R interval” or “beat interval (IBI)”.
In general, a low HRV (or a small change in heart beat) indicates that the body is under pressure from exercise, psychological events, or other internal or external pressure sources. Higher HRV (or greater variability between heart beats) usually means that the body has a stronger ability to withstand stress or recover from previous stress. At rest, high HRV is usually beneficial, while low HRV is unfavorable. When in an active state, a lower relative HRV is usually advantageous, while a high HRV may be disadvantageous.
When to use heart rate (HR)
It is best to use your heart rate during exercise. It is an important tool for training the cardiovascular system or monitoring the impact of training on the cardiovascular system in real time.
When to use heart rate variability (HRV)
HRV is best for rest (usually the first thing in the morning, or a rest activity such as meditation). It is an important tool for understanding overall health, resilience and ability to withstand various stresses. HRV can be used as a routine physical examination to determine its readiness to withstand stress on a specific date.