Augmented reality, AI and advances in sensor design mean wearable devices could put athletic trainers on the bench, as Alex Brinkley finds. Not everyone can afford a personal trainer to stay motivated and on track in the gym or on the sports field. For those who want personalized advice at no cost, the sensor industry takes over. By tackling some of the conventional design challenges, it’s poised to be the next disruptor in wearable technology. Smartwatches have been monitoring our heart rate, step count, and calories burned since the first FitBit launched in 2009. Smartwatches followed in 2014, and the health market has never looked back. The design of fitness…