Can anyone help? I'm 47 just took up as I call it adventure running (and I love it ). My goal for this year is to do the Y3Peaks as quick as I can. I'm no racing snake I did 20 mile on sunday mix country/road, in 3hours 17mins. I was happy with that to be honest. My heart rate and pace dont match, if I stick to a pace which would be to do a marathon in 4 hours, my heart rate works in the 80% to 90% if I work my heart rate between 70% to 80% to maintain the distance, my pace drops off. I feel ok ish at higher heart rate but after a while i imagine lactate acid may not get removed.

Should I maintain pace for time? or stay in the heart rate zone for distance, and hope time improves?

or should I just put my trainers on and get on with it?

I'm so confused