Good idea! The paper describing the breathing detection using radio is here: https://people.csail.mit.edu/fadel/papers/vitalradio-paper.p...
The paper on the heartbeat and breathing detection takes into account that heartbeats have repeating envelopes (signal shapes).
Would a wireless EMG be able to detect muscle activation and the source position(s) on the body of the signals as well?... Quite interesting.