I'm a little confused about THR, from what I've been reading in the past, its 70 to 80% of your MHR. And you should do cardio in your THR to burn the optimum amount of fat.
The problem started when I got one of these Heart rate monitor watches and the instruction read that for the best Fat burning, you should stay between 50 and 70% of your MHR.
It went on to state that 70-80% or Fitness Zone as they called it, should only be done "periodically to improve your fitness".
So what now? Do I go with 50-70% or 70-80% and risk cannibalizing my muscles.