People In China Are Putting Fitness Trackers On Bananas: Here’s Why

Apparently, people in China are strapping fitness trackers onto bananas and other everyday objects. But why you ask?

According to recent reports, placing your fitness tracker on toilet paper rolls, bananas, and even stuffed animals will actually show a heart rate reading.

Chinese tech site Abacus conducted a research and reported that Xiaomi Mi Band 3 fitness trackers are displaying a heart rate of 81 BPM when strapped to a roll of toilet paper. That heart rate apparently decreased when the tracker attached to a coffee mug (to 72 BPM), then went up again when attached to a yellow, potassium-rich banana.

Strangely though, the Xiaomi Mi Band 3 wasn’t alone in giving out the bizarre heart rate readings. An Apple Watch Series 4 was also reported as doing the same. However, the heart rates were just a bit lower than the Mi Band’s. Ticwatch, an Android Wear smartwatch went up to 130bpm for the mug.

Bananas and mugs provided a much stronger and quicker heart rate reading than toilet paper rolls, which helps to shed light on what actually is going on here.

Gizmodo explains “To detect the 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.”

Toilet paper has almost no reflective surface as compared to a mug or a banana, which explains the irregularities in the readings.

Also, fitness trackers were never actually designed to distinguish between human and bananas. The software is designed for only one purpose: To detect a heart rate from a human wrist. So no matter which fitness tracker you’re using, a banana will always yield an inaccurate heart rate reading simply because it doesn’t have a pulse and is apparently also more reflective than the wrist.

Xiaomi hasn’t offered an explanation yet but directed users towards a post on China’s Q&A site Zhihu, where the user says that it’s perfectly normal for certain objects to reflect light signals and confusing the sensor.

Also just to be clear, detecting heart rates on inanimate objects doesn’t necessarily mean it’s inaccurate at detecting your own heart rate.

So go ahead and have that post-workout banana. It doesn’t have a heart.