I have been running seriously for about 6 years now and have done 10 HM races. My age is 54 and my max HR is about 175 and RHR sits as low as 32 when I am relaxed. I tend to run 75% of the time at an aerobic pace with HR in the 130 - 135 range. Once a week I go with a younger colleague and its more high intensity. between 5 - 9 mile runs usually at a much quicker pace than my more relaxed runs, but you need some high intensity right?
Last night we did a 5 miler and I averaged sub 8 min miles (good for me) but HR was averaging 159 over the whole run and peaking out at 175. I am training for a HM in spring and would love to be able to average sub 8 min miles but am worried that doing 13.1 miles at this sort of pace could be to much. Is it?
I have done HMs as I said but its only recently that I have had the luxury of being able to monitor HR regularly.