Yes I've heard about biofeedback being used for muscle tracking. It's supposed to be great for training!!
It’s like meditation with science :)
Research suggests that biofeedback has the potential to improve athletes' response times and coordination. It has been recognized that concentration improvement from biofeedback contributes to enhanced performance! Paul, M., Garg, K., & Sandhu, J.S. (2012). Role of biofeedback in optimizing psychomotor performance in sports. Asian Journal of Sports Medicine, 3(1), 29-40.