Extending monitoring beyond the wrist

I train 3 times a week for approx 2 hours a session I cannot wear the watch as traditional martial arts don’t allow it I have managed it a couple of times due to poor turnouts and was surprised at just how many calories burnt

I know I can add the exercise times manually but still have to do extra session on my bike to close my rings I am wondering is there a way to wear the watch around your torso like some chest monitors or is there a device I can ware on my body to connect to the watch