Theres a chart at my club that says best fatburn is at 60Q% heart rate thing, you know what I mean. I have been doing a stationary bike because my knees are too messed up to run. I have been keeping my heart rate around 165-170 which according to the chart is about 80% for my age and more of a cardio instead of fat burn. My intentions are fat burn, so should I alter my work to lower my heart rate and burn more fat? Or does a higher intensity burn fat and work on cardio? Im so confused.
Search online (or here) for "interval training" or "HIIT" and read up. An excellent article on here that I alwasy remember by name iscalled "the Running Man" - it discusses this too.
There are thousands of similar, excellent articles on the web that will all tell you the same thing: the greater the workout intensity, the greater the fat-burning and muscle preserving/building effects.