High resting heart rate in fit 37 yo, no caffeine. Why so high?

Tamara · Yahoo User

I am a 37 yo female. I walk (brisk) 45-90 minutes 5-7 days a week, do strength training 3x/week. My resting heart rate before getting out of bed this morning was 81. My sitting heart rate is around 90. Avg HR during brisk treadmill walk last night was 135, max HR during walk was 167. An hour after my walk, my HR was still around 100.Readings are not taken near sugar intake. I do not consume any caffeine. I am a healthy weight (121 at 5' 4.75"). I wasn't worried/anxious during the readings either.I don't know what my readings were previously. I just got a heart rate monitor and so only now have checked. I double checked with my pulse to confirm that monitor is correct. Yes, I do know how to take an accurate pulse.I could understand a higher HR if I was older, overweight, out-of-shape, anxious, taking in stimulants, or using a faulty heart rate monitor.But why is mine so high? Thanks,Tamara