The sports monitoring function of smartwatch has become one of its core selling points. It can record the user's sports data, such as steps, distance, calories consumed by exercise, exercise trajectory, etc., to provide users with a basis for sports analysis and health management.
Step monitoring is one of the most basic sports monitoring functions of smartwatch. Generally speaking, smartwatch uses built-in accelerometer to sense the movement of the wrist and converts it into steps according to a specific algorithm. In normal walking and running, the step monitoring of smartwatch is relatively accurate, with an error of about 5% to 10%. This is because the accelerometer can accurately capture the periodic swing of the wrist during exercise. However, when the user performs some atypical exercises, such as walking with a small arm swing, swinging the arm quickly but not moving the foot, the smartwatch may misjudge and cause inaccurate steps.
There are two main ways for smartwatch to calculate exercise distance. One is to estimate by steps and user-preset stride, and the other is to use GPS positioning technology. The accuracy of the distance calculation method based on stride depends largely on whether the stride set by the user is accurate. If the stride setting does not match the actual situation, there will be a large error in distance monitoring. GPS positioning technology can accurately record movement trajectory and calculate distance in an open outdoor environment, with an error of about 1050 meters. However, indoors or in places with weak signals, GPS signals may be lost or inaccurate, resulting in deviations in distance monitoring.
The calculation of calorie consumption is more complicated, and smartwatches usually estimate it by comprehensively considering the user's basic information (such as age, weight, height), exercise type, exercise intensity and duration. However, due to the different metabolic rates of each person, the calories consumed by the same exercise for different people will also be different, and it is difficult for smartwatches to accurately take these individual differences into account. In addition, there may be errors in the identification of exercise types. If the smartwatch misjudges one exercise as another, the calculation of calorie consumption will also be inaccurate. Therefore, the calorie consumption monitoring data of smartwatches can only be used as a rough reference, with an error of about 20%-30%.
In the case of a good GPS signal outdoors, the movement trajectory monitoring of smartwatches can accurately record the user's movement path. However, in urban high-rise dense areas or indoors, GPS signals are easily interfered with, resulting in drift or discontinuity in the movement trajectory. Some high-end smartwatches will combine other sensors, such as barometers, gyroscopes, etc., to assist in correcting the motion trajectory, but errors cannot be completely avoided. When exercising indoors, due to the lack of GPS signals, smartwatches can only perform relatively simple motion trajectory simulations through accelerometers, etc., with relatively low accuracy.
Most smartwatches use photoelectric heart rate sensors to monitor heart rate. This sensor calculates heart rate by emitting green light and detecting the degree of light absorption by blood. When stationary or in a light exercise state, the accuracy of photoelectric heart rate sensors is high, and the error is usually around 510 beats/minute compared to professional heart rate monitoring equipment. However, during strenuous exercise, factors such as wrist movement and sweating will interfere with light detection, resulting in a decrease in the accuracy of heart rate monitoring, and the error may reach 1020 beats/minute.
The sports monitoring data of smartwatches can provide users with valuable information to a certain extent, but due to the influence of many factors, the accuracy has certain limitations. When using the sports monitoring function of smartwatches, users should understand their error range and use it as reference data rather than absolutely accurate data. At the same time, with the continuous development of technology, the accuracy of smartwatch motion monitoring is also constantly improving, and it is expected to provide users with more accurate motion monitoring services in the future.
