I have been doing long sessions of cardio about 1 hour on the revolving stair case, first thing in the AM

I do the cardio stimulant free........personally I think its bad to do cardio on stimulants seeing as it artificially raises yoru heart rate.


so I do cardio with a heart monitor ......I notice something very strange.

the first half hour my heart rate stays steady about 128, working medium range

then its seems to switch to a higher level.........it does not feel bad it just feels that I am working harder all of the sudden without a increase in resistance....I find I have to then cut back all of a sudden in order to stay at my target heart rate?


again it does not feel bad..........I would be interested as to why.

the jump in heart rate is pretty substantial

is this because my body spent all glycogen from the 8 hour fast of sleep, and is now using fat, thus making your system work harder?

thanks for the feedback

ps

the cardio is very unpleasurable in those long sessions but I am noticing a visible differnence in my fat reserves for the better