They can be seen everywhere: at the wrists, in the ear, clipped to the belt. Wearables are small technical assistants who are built to collect and partially also to analyze data. Some of them collect measurable health data, others "only" count their user’s steps or measure the surrounding UV radiation. The fact is, however, that wearables are en vogue and are used for many different cases.
Smartphone apps and wearable sensors have the potential to help people make healthier lifestyle choices. Self-monitoring therefore is one of the core strategies for changing cardiovascular health behaviors. On the other side, patients benefit from sharing their data with doctors and electronic health record (EHR) systems.
They are exciting for enthusiasts of the "quantified self" movement and extremely useful for athletes: wearables that measure and store numerous body parameters and enable long-term data analysis. Yet, for their use in medicine and rehabilitation, manufacturer and user both need to ask themselves how safe the devices actually are.