I was reading EKGs at a dental conference years ago, when I was shown a really wacky one with a resting pulse of 29. The guy was a young dentist who swam competitively, still, and swam 6 days a week for ~90 minutes. I had him come back later and jump around for 10 minutes. His EKG looked fine. I told him I thought it was OK< but he should show it to his doc when he got home.
Wasn’t Merckx supposedly in the high 20’s, too?