Fitness trackers are designed to help people monitor their daily progress in improving health anytime and anywhere. The device has been widely used to monitor weight and to promote healthier habits, including sleeping, eating and exercising. 

However, a number of experts have been raising concerns about the effectiveness of the technology. Some of the devices were found producing inaccurate fitness data, which may affect how people plan their lifestyle and potentially lead to unnecessary activities. 

Fitness trackers use different sensors to collect data. In most products, heart rate is used to calculate calories while motion sensors are used to count movement.

Heart rate monitors use an infrared light that penetrates the skin and looks for subtle changes in the color of the blood. However, this technology is far from perfect, according to Adam Sinicki of Android Authority.

There are multiple factors that could affect the appearance of blood vessels. It includes physical activities that cause changes in the amount of blood reaching the limbs and the different heart rates of individuals.

“Heart rate alone is not an ideal indicator of calorie burn,” Sinicki said. “The assumption is that when the heart pumps faster, you are creating a demand for oxygen and energy and thus probably engaging in an activity that is ‘costly’ from an energy perspective.”

Physically fit people are known to have lower resting heart rates. Blood and air pressure, ambient temperature and mood can also cause sudden heart rate changes. 

A study in 2015 also showed that fitness trackers commonly provide inaccurate data on the distance a person traveled, overestimated total sleep time and miscalculated number of calories burned.  

Too much numbers

Another problem with the devices is obsession with numbers. This is not a technical concern but is also important to know due to its impact on health. 

People who use fitness trackers daily tend to rely too much on numbers and lose focus on how exercise makes you feel. Some may rely on the device to tell whether they are healthy or not. 

Researchers previously found that many people who buy fitness devices stop physical activities as they lose interest in using the devices over time. The study showed that one in three users stops wearing the device within six months of buying it.