Quite a bizarre trend is doing the rounds in China: strapping fitness trackers to bananas and other objects!
People in China have been strapping fitness trackers to all sorts of things from bananas, to toilet paper rolls, to coffee mugs and even stuffed animals!
Interestingly, the reason for this practice is even weirder. Placing fitness trackers on such objects actually yields a heart rate reading! The Chinese site Abacus reported that a particular model of fitness trackers, the Xiaomi Mi Band 3 fitness tracker displays a reading of 81 BPM heart rate when attached to a roll of toilet paper! This has piqued the interest of the general public who are now concerned about the validity of the readings given by these fitness trackers.
Attaching the fitness tracker to bananas and coffee mugs yields an altogether different reading so the readings cannot be attributed to the effect of ambient conditions. What is even more alarming is that the same phenomenon was observed with an Apple Watch Series 4 which slightly lower but overall similar heartrates when attached to inanimate objects.
Since bananas and mugs were able to provide quicker heart rate readings than toilet paper rolls, it may have to do something with the operating principle of the fitness trackers which use a beam of green light and its level of absorption by the blood to gauge the heartbeat rate.
According to Gizmodo:
“To detect heartbeat, trackers beam a green light at a user’s wrist. Blood absorbs green light, so when blood flows faster it absorbs more green light. This process, known as photoplethysmography (PPG), is a relatively simple way to detect how fast a user’s heart is beating.”
Thus, just as an inanimate object can reflect/absorb green light at different levels, the heart rate obtained from the fitness tracker for these objects also varies.
Nevertheless, this trend is creating a lot of doubt amongst users and may not bode well for fitness tracker companies using this principle of operation for their fitness trackers.