Carbonfiberboy 

I surmise that the issue is that he injured himself weight lifting somehow, probably by, well, overdoing it. There's no warning for that one. When you've done it, you've done it. Don't ask me how I know. One could do that cycling training as well. You're 70 and climbing a pass or doing VO2max intervals and all of a sudden your HRM says 210. Not me, but friends. So stuff happens. But this and that have nothing to do with ordinary fatigue while cycle training.

Stuff also happens when you're carrying something and just step down and turn wrong. A friend's ski pass is now just a piece of useless plastic.

There are technical and non-techinical fatigue markers which one can monitor, for example morning resting and standing HRs, HRV, inability to raise a HR out of zone 2, poor sleeping, irritability, and others. I got so tired once that I couldn't raise a HR over 105 no matter what I did.

But riffing on "the damage has already been done," hey, damage is what we're after! Nothing happens without a little damage. Like I say, if it didn't hurt, I wouldn't be doing it. Not really, but it's a comforting attitude.

canklecat

According to a fairly recent trend, heart rate variability can help identify training and recovery problems that may not manifest obviously enough just going by how we feel.

I was skeptical about HRV when I first heard about it, but in retrospect that was because the videos and articles were trying to sell products and programs rather than just inform consumers. Too many of the proponents made the mistake of chattering enthusiastically about meditation, mindfulness, biofeedback and pop psychology buzzwords that trigger my skepticism. So I ignored the whole HRV thing for a year or so.

However -- possibly because I mentioned it to a friend on Facebook or clicked on an article -- Google news and other news aggregators I use recently began suggesting stories on HRV. (That's one of the benefits of enabling tracking for some purposes.) An article mentioned Wattson Blue and Elite HRV apps, so I've been using both for a couple of weeks. Wattson Blue uses the phone camera and steady light for fingertip readings -- seems crude but it works reasonably well.

Elite HRV does sell products but also works with other brands of heart monitors, including my Wahoo Tickr, so that's what I use. However pairing the Tickr to Elite HRV is a chore. Some days it takes up to 10 minutes of repeated fiddling, phone reboots, etc, to get the damned thing to work with the Tickr. This is the most common complaint about Elite HRV from people who've tried the app. So I tend to use it only once a day to minimize the frustrations. When it works the information is useful.

Generally speaking results from these HRV apps tend to correspond with how I perform that day in bike rides and workouts -- good and bad. Due to injuries (hit by cars twice in less than 20 years, busted up neck, back and shoulder), illness (Hashimoto's, a pesky but non-fatal autoimmune disorder that killed my thyroid after years of gradual deterioration), surgery for thyroid cancer, and just being older (62 now), I rarely feel well in the morning. I can remember exactly one day in all of 2019 when I woke early and ready to join a group bike ride. Most days it's a chore just to drag my carcass out of bed, pee and get some coffee. If anyone asked me on a typical morning if I planned to ride my bike later that day, I'd say not only no, but hell no.

Pain is no longer a useful indicator of my fitness or capacity for exercise on any given day. (This gets into a whole nuther realm of pain management and science, which is being investigated by a UT Dallas team of researchers, who are studying why pain persists long after an injury has healed, and how to safely relieve useless pain, while not masking valid pain signals that indicate a current, possibly serious injury that shouldn't be ignored.) But I'm not gonna take fistfuls of opiates (even though I can get 'em from my doc). And I'm not gonna sit around moping on the sofa, tempting though it may be. But it would help to have a tool to give me some hints about when I should rest and when I should get busy. Because my body isn't handling those guidelines anymore.

So on days when the HRV apps indicated my body appeared to have had adequate rest, nutrition, etc., and I went ahead and rode and/or worked out, I usually felt pretty good. Even made some progress after having plateaued for months. And there have been a couple of days when I felt the same as usual in the morning -- miserable, achy and exhausted -- and the HRV apps warned that either the results were skewed by glitches, or my body was out of whack and I should rest. On both days, I had indeed been extremely stressed out by life stuff and hadn't eaten properly or slept well for a day or two. And the post-workout HRV checks also seem to reflect the intensity of my rides and workouts.

Now, there may be some placebo effect, wish fulfillment,etc. --- basically, the HRV data showing me what I wanted or expected. But for many things in life, that's just as valid as purely physical issues, in terms of how it affects our perceptions of well being.

So, HRV may be useful for some folks who are serious about training, or pursuing fitness, and either usually wake feeling great or, in my case, usually feel like cold poo every morning, regardless of what our bodies are actually capable of.

OBoile

Just to add to your strategy here: when in doubt, be conservative. Taking a day off here or there isn't a big deal. Adding miles a bit more slowly isn't a big deal. Getting an overuse related health issue may result in weeks or months off. That is a big deal. It's not how fit you are 3 weeks from now that matters, but how fit you are 3 months or 3 years from now. In the long run, consistency matters.

One other overlooked factor in consistency: enjoyment. If you're dreading riding on a given day, take the day off. If the weather is terrible, take the day off. It's great to have a plan and a schedule, but recognize that 100% adherence to that plan is likely impossible. If you do 85% to 90%, you'll get almost all the benefit with far less stress.