This is just a quick question regarding my resting heart rate. It has been in the high 40's to low 50's for a couple of years, but recently has dropped to the low 40's. I am a runner (approx 25 miles per week, with a couple of marathons behind me, in which case I run 50 miles per week in training), but I am not an Olympic caliber athelete. Is it normal for my heartrate to be this low? I am also on synthroid for hypothyroidism, so have regular checkups for this condition. I also have very low blood pressure.
Thank you!