Hi Amanda. Thank you for your note. I'll take a look at the study. Thank you for sharing. I'm pretty active. I'm on the bike 10-20h/wk (not including stops, stop lights, etc; just turning the cranks.) I average about 12-15h. Pre covid I was running about 10h/wk on the bike, two bootcamps, and two sessions with a personal trainer per week. Since covid I've migrated most of my activity to the bike. In q1 I had some real issues with afib/flutter. That took it out of me, made training much much harder, and left me feeling pretty beat up after the fact. But, two weeks after my last cardioversion in April I took off to do 350 miles along the SoCal coast. I did it, was happy I did/could, but it was rough. I was "undertrained" and on an antiarrhythmic at the time (which I later found out also introduced a second beta blocker.) Getting my HR up was nearly impossible and getting over the coastal range (with bags on) was a challenge. And I did it. From there I've done about 700 miles of solo, self-supported bike tours in France and about 700 miles of solo, self-supported bike tours all over Washington State & Oregon coast this past summer. I decided I'd just focus on volume and not do any intensity training (outside of the normal hills/mountains) . . . I wasn't doing any interval type training at all. Having laid down a reasonable "base" at this point of about 3500 miles (mostly low & slow), I'm shifting to doing some structured training on the indoor trainer once or twice a week. These are 60-90 minute sessions of long (5-15 minute) intervals at about 85% of max power output; they're not sprints. I dont have the guts or the desire to do 90 second "all out" repeats. I'm mostly happy with the volume I'm doing. My average speed is off a couple miles/hour from a year ago. I'm hopeful a little intensity training will bring that up some but I'll be ok if the "new normal" means I continue to plod along at my current pace. I dont really know how trainable my heart is at this point. Volume takes more time than intensity but supposedly provides more resliency which is mostly what I'm after. I'm not competing . . . but I'd like to hang with the "slow-kids pace group" I'm riding with. I'm also adding back in the bootcamp twice/week; not sure I can do a situp anymore 😉