When I do 12-3-30, I find my heart rate settles consistently between 142 and 146 bpm. I feel good, not out of breath, but I sweat a lot doing this. I'm 56 and this heart rate is above the target zone for my age. But as long as I feel good I don't think it's a problem.

Anonymous wrote:My heart rate is in the 180s, the very top of my range, when I do 12-3-30.

Way too high. Decrease the incline