Study: The Apple Watch is not only worn on the wrist and can also be worn in unusual places for unusual reasons

Heart rate measurement is now possible with inexpensive wearables and is now standard fare in current smartwatches. The heart rate is measured via an optical, non-invasive procedure. Specifically, light is emitted which is reflected by the body and can be detected again by the smartwatch's photo sensors. Blood, for example, weakens the intensity of the light. Since the local blood volume changes with the heartbeat, this allows for a measuring of the heart rate.

Smartwatches such as the Apple Watch are intended to be worn on the wrist, just like watches. It has now been proven that heart rate measurement there can be carried out precisely and easily. A new and rather trivial observational study now shows that the Apple Watch not only produces precise measurements on the wrist. The study utilized a simple experimental setup in which test subjects wore an Apple Watch 8 on both their upper arm and wrist. Surgeons who performed robot-assisted procedures served as the test subjects.

The subsequent analysis showed that there were no systematic errors between the two carrying locations. Accordingly, the Apple Watch generates precise measurements when worn on the upper arm. This means that the Apple Watch does not have to be worn exclusively on the wrist. However, the situations in which a smartwatch cannot be worn on the wrist are likely to be quite unusual.

One possible application would be in the medical field, for example, where wristwatches are likely to be banned for reasons of hygiene and sterility. In such stressful jobs, it may be sensible to keep an eye on your heart rate. This could also apply to laboratory workers.