Got a somewhat perplexing for me cardio question. I start out OK for the first 25 min or so, keeping my heartrate right where it should be. However, after this point my heartrate steadily starts to climb, and I have to lower the intensity of the cardio in order to keep it in the proper range. Any cardio veterans know if this is normal?
Could well be a stupid question, but heck if I've never done much of it I just won't know now would I.