it will hinder ur gains... (if you need proof or whatever, i can get articles and research to back me but it does)... it u are goin to use it for kcal loss, do HIIT of some sort. and the 60% he was talkin about was 60-80% max heart rate... on average the way you can figure that is you take 220-(your age) x .6 = 60% HR and the same for 80% HR