I'm 31 and in decent shape, but I also have pretty bad exercise asthma. Normally, when I work out, especially running and other cardio stuff, my breath-fitness tops out when I'm getting around 170-180 BPM heart rate.
Tonight, I was on the treadmill turned to max elevation (setting 15) and about 3 MPH with a weight (I couldn't run because my knee was bugging me). I was getting slightly winded and asthmatic, but nothing too bad. But my heart rate was up between 190-200 BPM, and I could maintain it for at least 90 seconds during my intervals. It felt like a good workout, but I wasn't knocked flat like I often am when I run. It was much more of a core workout, and I liked it.
I'm not worried at all, and I know the 220-AGE formula isn't exactly reliable, and my exercising heart rate is usually pretty high relative to the formula. I'm also aware that high heart rate is not always directly correlated with high breathing rate (however, in my experience it often is), although the converse seems pretty reliable. I'm wondering:
- What is a mechanism that would explain why I had a very high (even for me) heart rate, but wasn't breathing nearly as heavily as usual?
- Is this a sign I wasn't getting a good enough workout? If I'm doing high-intensity stuff, do I want to go by (a) heart rate, (b) the intensity of my breathing, or (c) the intensity in other muscles (e.g., my heart rate on stationary bikes is usually relatively low, because my legs are the limiting factor there)
- Anything else relevant?