Why People in China Are Strapping Fitness Trackers to Bananas

Apparently, right now in China, it’s trendy to strap fitness trackers to bananas and other inanimate objects. But why?

Interestingly, according to recent media reports, placing fitness trackers on toilet paper rolls, bananas and even stuffed animals will actually yield a heart rate reading.

After quite a bit of research, Chinese tech site Abacus (via Gizmodo) reported that Xiaomi Mi Band 3 fitness trackers will display a heart rate of 81 BPM when attached to a roll of toilet paper. That heart rate decreases when attached to a coffee mug (to 72 BPM), then rises again when strapped to a potassium-rich yellow banana.

Oddly enough, the Xiaomi Mi Band 3 wasn’t alone in these bizarre readings. An Apple Watch Series 4 also reported similar heart rates, they were just a bit lower than the Mi Band’s.

Apparently bananas and mugs were able to provide stronger and quicker heart rate readings than toilet paper rolls could, which helps to shed light on the funny business that’s occurring here.

Gizmodo goes on to explain that “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.”

Expert PPG researchers can attest that PPG sensors can easily misread and misinterpret “heart rates” when placed on an object that can reflect light.

Toilet paper has a less reflective surface than a mug or a banana does, which helps explain the inconsistencies we’re seeing here.

But, to be fair, fitness trackers aren’t designed to differentiate between human contact and banana contact; so no matter which fitness tracker you use, a banana will always yield an inaccurate heart rate reading simply because it doesn’t have a pulse (and is apparently more reflective than your wrist). Watch Abacus‘ full video below!