Wearable technology is one of the top fitness trends for 2017. And in the US, smart gadgets to help you stay healthy are some of the most popular gifts this holiday season for the second year running. These wrist bands are all the rage for helping you stay fit. Overall demand for such personal devices is growing so fast that the industry is expected to be worth 34 billion US dollars by 2020, according CCS Insight, which provides market information, analysis and intelligence for companies focusing on the mobile and wireless sector around the world. Wearable technology departments in many stores are packed with products this season as popularity increases for smartwatches and fitness and health trackers.