@jreinfeld My heart rate did normalize. Working off memory (timeline might not be precise) I got back into training with zone 2 work at the low end and progressive intensity still within zone 2 for about 6 weeks. Once my heart rate for endurance rides was back to a pre-sickness level, I started a low volume TT training plan where I added easy zone 2 work rides twice a week to bring training up to 5 days per week for cycling. Over the initial 6 weeks, my resting heart rate returned more or less to normal and during the TT training block (9-12 weeks) resting heart rate was slightly elevated after hard interval days and returned to normal after recovery days. As for today, my resting heart rate varies based on intensity. During a recovery week, it’s around 50-55. During a training week, it’ll be around 52-55 going into a hard day, 55-58 after a hard day, then back to the 52-55 range before repeating the process. One difference between now and prior to getting sick, I had some more flexibility for higher training volume around 10-15 hours per week when you include running and strength training. Today, I am around 9-11 hours with a mix of 6-7 from cycling, 2-3 from strength training, and the remainder from running. If I increased volume and reduced intensity slightly, then I think the physiological factors would align to bring about a lower average resting heart rate, but it’s not a direct apples-to-apples comparison on training since I am doing 20-30% less volume with a little more intensity which skews the recovery cycle. Overall, I did recover and get back to normal training loads, all else held equal. Hope this helps. Let me know if you have any follow-up questions and I’ll try to answer them as best as possible.
Edit: I forgot to mention that during the initial 6 weeks of progressive zone 2 work that I probably got back to “normal” sooner, but locked in on a six week timeline before starting a training plan. My thought was, “alright, time for some aerobic base building for six weeks as I fully recover” so the timeline towards normalcy might be faster.