Wearable Trackers Estimate Fitness Levels Without High-Intensity Exercise
May 27, 2020
Researchers developed a method to estimate cardiorespiratory fitness levels that could be applied to data acquired by wearable fitness trackers during daily activities. This could facilitate tests for those who have low exercise tolerance and may reduce the need for fitness tests under medical supervision.
Cardiorespiratory fitness is the ability of the cardiovascular and respiratory systems to supply enough oxygen to the muscles during physical activity. People with low cardiorespiratory form may have an increased risk of heart disease, heart attack or stroke. Testing the amount of oxygen that the body uses during exercise (VO2max) can evaluate these risks and also function as a preventive measure. However, people generally have to train until exhaustion to measure VO2max and such tests require medical supervision and specialized equipment. In addition, it may not be safe for anyone who has to undergo cardiorespiratory fitness tests to exercise at maximum effort. Methods that use low intensity (submaximal) exercise do not always provide accurate results like maximum tests.
“The assessment of cardiorespiratory fitness during daily activities can be very promising to allow its constant monitoring in a discrete way, as it would simplify the self-assessment by eliminating the need for equipment for the exercise typical of submaximal tests” team of researchers wrote.
The research team studied healthy adult volunteers between the ages of 18 and 55. Volunteers participated in a cycling test to measure their VO2max before the study. The researchers measured the height, weight, fat, and muscle mass of the volunteers and equipped them with a chest strap heart rate monitor and an activity monitor worn around the wrist. Volunteers were asked to wear the devices continuously during the daytime for five consecutive days while following their normal daily routines.
Using a fitness index to calculate the relationship between energy expenditure and heart rate during physical activity, the researchers predicted VO2max for each of the volunteers. By comparing the estimated VO2max with the real values of the cyclic test, the margin of error was about 10 percent. This figure is lower than the average error rate reported in previous research using sub-axial methods to measure cardiorespiratory fitness. “This gives us confidence that the presented method offers valuable predictions of [cardiorespiratory fitness] useful for classifying individuals of different fitness levels,” wrote the researchers. “Future work should focus on extending the validity of the method presented with data to groups of the elderly and patients.”