Because I'm sometimes a little crazy, I picked this week as the week to try to really do a HIIT workout...
Well, that isn't exactly right, I hit that 'drop over dead' heart rate by accident yesterday afternoon during kickboxing and could totally tell that what I had been doing up until then wasn't actually HIIT (music motivates me to move apparently.)
Here is my question... Does that "I'm about to fall over, can't do anymore" heart rate vary from day to day for everybody? Yesterday it was 193-195, for about twenty seconds before I had to slow down. Today I felt the exact same way I felt at 195 yesterday but was only at 185, which yesterday I could maintain for several minutes before I slowed back down. Is it lower today because I'm more fatigued from the workout yesterday? I did exercise later in the day yesterday and did pretty intense kickboxing for 30 solid mins (the HIIT came in during the last two songs...)
Kickboxing is going to be a tough one for me to control, because I really enjoy it so I don't pay as much attention to wearing myself out...