“With the continuous advancement of the digitization process, the application of optical heart rate sensors in wearable devices is becoming more and more extensive.
With the continuous advancement of the digitization process, the application of optical heart rate sensors in wearable devices is becoming more and more extensive.
The countless apps on these devices provide everything from personal activity and fitness levels to health. Precise biometric sensor data can provide accurate fitness/health assessments, but what exactly can designers and engineers do with these assessments?
Most wearables on the market today are launched for sports and fitness use cases, but we can start to see wearables transforming into personal health devices that provide meaningful guidance on people’s health. This is because the photoplethysmography (PPG) sensors in these wearables have achieved a level of accuracy that is sufficient for many of the health and medical use cases that have been proven by electrocardiography technology.
Here are some examples of how these assessments can be used and how they can be applied to health and medical wearables in the future.
VO₂ max, a measure of physical activity and the physical responses associated with it, is a key factor in determining the level of improvement. Some wearables today are starting to use VO2max (maximum oxygen consumption) to measure chronic changes in cardiovascular fitness. The higher the VO2 max, the better the performance during aerobic exercise. However, wearable devices with the ability to measure VO2 max could also have applications in health and medical applications. For example, evidence suggests that higher VO2 max is also associated with a lower risk of death and improved recovery from heart disease.
Resting heart rate, the word “rest” may not be the first word that comes to mind when people think about fitness, but a resting measurement of heart rate can be a good indicator of fitness level. During periods of inactivity, a decrease in resting heart rate was associated with increased fitness. The lower a person’s resting heart rate, the more likely he is to slow the progression of cardiovascular disease.
Heart rate recovery, likewise, measuring heart rate recovery — the heart’s ability to return to normal levels after exercise — can also predict fitness levels and heart function. A healthy heart recovers faster than an unhealthy heart. A higher heart rate recovery rate indicates better endurance and better cardiovascular fitness. To assess your heart rate recovery, you can look at the difference between your heart rate during exercise and one to two minutes after you stop exercising.
Heart rate response, another useful assessment from the heart rate sensor, after about a minute of exercise, is the heart rate response to exercise, which is a physiological response. Increased working muscle activity leads to increased sympathetic nervous system activity. The lower the fitness level, the more responsive the heart rate is to exercise. With regular training, the body adapts. While heart rate still increases with exercise, the body has to work harder to achieve the same pace. A higher heart rate response, combined with chronotropic insufficiency, also helps predict carotid artery disease.
Cardiac efficiency, Regular exercise also improves cardiac efficiency, which is the ratio of the work the heart does to the amount of energy it needs to complete the job. The more efficient the heart is, the fewer beats it needs for physical activity. Cardiac efficiency is a major indicator of heart health. A drop in heart rate is associated with many cardiovascular diseases, including high blood pressure.
Heart rate variability (HRV), physical activity or stress on the body, can also be used to assess changes in time between heart beats by HRV. This measure can indicate psychosocial or mental stress, as well as excessive exercise. HRV monitors the physical impact of stressors, which is related to fatigue (mental and work capacity) and readiness to perform mental and work tasks. HRV can also predict the incidence of arrhythmias and atrial fibrillation. Professional athletes have been using HRVs for a while, but they are only just starting to gain traction on consumer devices.
There have been many announcements recently about new capabilities for wearables to detect atrial fibrillation, arrhythmias, core body temperature, and more. These capabilities are provided by the same optical heart rate sensors that use PPGs that are used in a plethora of wearables today.
All in all, wearables are transforming into personal health devices that provide meaningful guidance on people’s health.