For the better part of two weeks, I’ve experienced all kinds of illness. Woke up on Tuesday, December 28th with a headache, fever and general icky feeling. Since I had spent Christmas Day among 80,000 others at Lambeau Field, and in a car with three others for 5 hours, I was likely going to catch something, whether it was the virus that cannot be named, the flu or a common cold. While I didn’t test positive for the virus that cannot be named, I did test positive for influenza A, I had all of the classic omicron symptoms. Add in the fact that my little sister, whom I spent the car ride with tested positive with the same symptoms, I treated it like I had the ‘rona and took my cocktail of drugs that cannot be named for five days. While the fever, headache and sore throat broke relatively quickly, I was still significantly fatigued.

My personal training workout on Monday, January 3 left me exhausted like it usually does. I rode the trainer last Tuesday and I could only tolerate six minutes without complete exhaustion. Decided to ride a different workout on Wednesday, a recovery effort. I finished it, but I still felt awful. Active recovery should make you feel good, not worse.

Turns out I probably could tell I wasn’t fully recovered despite not showing no symptoms. All I needed to to was look at the data that my Garmin Fenix is tracking. Garmin calls their heart rate variability metric Stress. (Full description here.) The week prior to my illness, I had an average stress level of 33. It sayed relatively consistent until Christmas Day (where I did a ton of walking around Lambeau and froze for three hours). The 26th was a really quiet day of relaxation.

Tuesday, when I first showed symptoms of an infection, my stress level was still low. But the next day when I felt the worst, my Stress level reached its peak which lead me to hover around 40 for the rest of the week. While from the outside I felt generally fine, my body still was fighting off whatever I had.


Looking at the chart below, my body was still fighting off whatever illness for the last week. Today, I finally had a normal energy level when I woke up. which corresponds to the Stress level today. While I am not doing anything differently for a Monday, It is clear that by body is in much better shape.

What does it all mean?

Probably nothing, but it is a data point. After looking at weeks worth of data prior to getting sick, my average Stress level was around 25. That’s my baseline. I also took a look at my Stress level after big rides in 2021 and the next day or two I typically had a higher than normal Stress score. With the Tour of Sufferlandria coming up at the end of February, I will likely look to this metric again to see if I need any more special recovery after a week of smashing myself on the trainer. Back-to-back cyclocross race weekends also will need additional recovery instead of going into a hard workout on Tuesday like I did this past year based on the data I’ve looked out.

All in all, it’s fascinating. Might not be entirely useful for day-to-day training decision-making, but having baseline data and analyzing trends will make identifying sickness and signs of overtraining possible.