Heart Rate Zone Training

Anyone here dabble in this?

Ive tried and got minimal results. My body looks in shape but cardiovascular is lacking.

The best results Ive gotten - believe it or not - were from the 2 quickest “insanity” workouts daily (alternating). That got my endurance in shape real quick. Im about to do it again since my current stuff isnt working.

I’ve just started looking into this.
I’ve started riding my bicycle and using a smart watch and my phone to monitor my time, distance and heart rate.

The good news is I’m in better shape than I thought, judging from my heart rate and recovery time after my morning ride.

I am interested in reading more info on the topic, I did a couple of quick searches to find suggested heart rate for age targets.