Garmin Delivers A Timely Warning

On Sunday, I set out to run for 105 minutes in Zone 2. I did indeed run the full 105 minutes, and then some, but I ran so slowly that I was very disappointed in my workout. After the first two or three miles, my heart rate didn't want to come down below about 154 beats per minute, which is just barely in the Zone 3 range. No matter how slowly I ran, my heart rate stayed up. By the end of the 105 minutes, I had only run 13.5 miles, and had done so a lot more slowly than I would have preferred.

Interestingly enough, five miles into my run it had already become clear to me that I was running a slower-than-normal pace and that my heart rate was elevated. So, I decided to mostly ignore my heart rate, and just focus on running with good form and a pace that felt relaxed to me. Even so, it didn't help. My heart rate stayed elevated, my pace remained slow, and by the end of the run, I felt awful. I felt badly because running slow is hard on the muscles and joints. A part of me wants to "trust the process" of training according to this fitness program, and another part of me wants to delete the workouts and run at my own pace. I could go either way on that, at this point.

Over the weekend, my 7-day Training Load hit 1,055, which is enormous. On Strava, my weekly Relative Effort was 721. That's almost 100 points higher than my highest-mileage week in years, which was two weeks ago, and almost 300 points higher than last week's score. That's a big increase, by anyone's algorithm. Perhaps Sunday's poor performance is simply a result of having had such a big increase in my mileage. To put this in perspective, I ran more miles last week with a rest day than I ran two weeks ago without a rest day. Hefty.

Or, perhaps my bad running day was just an unfortunate combination of unexpectedly hot, humid, and sunny weather combined with unexpectedly high post-breakfast blood sugar. I was also incredibly nervous for my big long run, for some reason, and it's possible that I somehow managed to "psyche-myself-out." I was pacing around the house a bit, too; maybe all that walking before my workout tired my legs out. Or maybe it was just a really crumby day, and there's nothing more to it than that.

What's interesting, however, is that Garmin was telling me that my training level was "Unproductive" on Saturday night, the night before my terrible long run. In terms of data, Garmin's algorithm said this because my VO2 max estimate had fallen by one point, from 61 to 60. As I wrote the other day, it's unlikely that my "true VO2 max" fell over the course of a day, and it's hard to say that a decrease from 61 to 60 is a meaningful decrease, anyway. But Garmin's algorithms seem to have detected something, because whatever changes they found were reported only a few hours shy of a really terrible run. That strikes me as being significant.

For Strava's part, they are reporting that my fitness level is higher than it's been in months, and that my fatigue level is almost as high as it's ever been. So all the data I see is consistent with all the other data -- nobody's "getting it wrong." But Garmin did a better job at an early prediction.

The accuracy and relevance of this early prediction increases my confidence in what Garmin is telling me. It's one thing to get a bunch of data reported at you and to look for training clues. It's quite another thing to get a piece of very useful feedback at the exact moment it is relevant to your training regimen. Garmin nailed it for me this week. I will pay much closer attention to what it says from now on, at least until they start getting it wrong.

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