I can tell when I'm crossing 162bpm (I think it's my personal aerobic threshold). If my HR below that I'm recovering; above that - fatigue starts to build up. A

I can tell when I'm crossing 162bpm (I think it's my personal aerobic threshold). If my HR below that I'm recovering; above that - fatigue starts to build up. Also I can tell when it's above 171 - itchy feeling from lactate start to build up much faster. I did VO2 max test once and went as high as 220. It feels absolutely horrible after 190 (long-time exposure to HR at that level most likely will do permanent damage to heart).