A math equation

Perhaps my dad can figure this one out...not me, I have an English degree.

I wore my heart rate monitor for the first time ever in a race. I've trained with it before, but am just trying to figure out how to use it effectively.

I forgot to stop it when I finished, and didn't realize it was still running until I had finished cleaning all the mud off of me. I stopped it at 6:20, when I had finished almost exactly 30 minutes before. I was probably near enough to my bike (where the receiver was attached) to register for about 7-8 minutes after I finished.

So...what was my TRUE average heart rate? It read that I had averaged 160 when I stopped it, but there was at least 20 minutes of a zero reading while I went off to clean up. So, 5 hr. 50 minutes of exercise, +/- 10 minutes of recovery (probably around 100 beats per minute) , +/- 20 minutes of zero reading.

My guesstimate is somewhere around 170. I had it in my mind (had done some rough calculations) that I needed to be around 167 to keep from generating too much lactic acid for my body to handle. Most of the time I looked down, I was in the 170's and 180's, but I couldn't read it for a while for the mud, and honestly didn't look at it for much more than the time reading.

I will probably set a window between 165-175 for my next race. I can set the watch to beep when I am out of that zone. Staying consistent is hard, but necessary in these types of races for ultimate results.