I have a heart rate monitor that I use mostly when I'm in a spin class. I've tried wearing it running, but all the upper body movement causes it to slip loose and give crazy readings like 122%. That did get me thinking, though - could I hit 100% of my theoretical maximum heart rate of 183 beats per minute? (Calculated as 220 minus your age in years) At spin class this morning, I tried pushing it and could only get to 96%. I've been able to reach 97% in the past, but I think it gets harder as I get in better shape because now I find my heart rate is lower for the same perceived exertion level.
I'm gonna keep trying. Hopefully my heart won't explode.