We do not use HR monitor(s). When our heart is beating, we can ride, when it quits . . . hey, our bodies are donated to science!
Seriously, a while back, the U of A did testing of folks that were at least 60 years old (yipes, that was 15 years ago). Volunteered and had sensors all over me and doing treadmill tests, etc. Maxed out at 183 bpm. Was told to lay down and relax while needles were shoved in my legs and they played soothing music. A few minutes of that and the grad student nudged me and said "are you awake?" Answered in afirmative. He then said " . . . but your heart rate dropped to 48" . . . my answer "well, you did tell me to relax!"
Oh, they paid me $15 an hour for my time!