The short version: A systematic review in the British Journal of Sports Medicine found that athletes' subjective self-reports — mood, perceived stress, fatigue, soreness — responded to changes in training load more consistently than common objective measures like resting heart rate or blood markers (Saw, Main & Gastin, 2016). Wearables are useful context, but the most sensitive monitoring tool most coaches have is what athletes tell them. The problem is that it's also the easiest data to lose.
There's a version of athlete monitoring where the coach opens a dashboard full of HRV, sleep scores, and readiness percentages, and knows exactly who needs a lighter day.
I like that version. I'm building software that uses it. But I don't think it's the most important part.
The most sensitive sensor is the athlete
In 2016, Anna Saw, Luana Main, and Paul Gastin reviewed 56 studies comparing subjective and objective ways of monitoring how athletes respond to training. Their finding was blunt enough to make it into the title: subjective self-reported measures trump commonly used objective measures.
When training load went up, athletes' self-reported fatigue, stress, and mood disturbance tended to get worse. When load came down, they improved. Objective markers — resting heart rate, certain blood and hormone measures — were less consistent in picking up the same changes.
That doesn't mean wearables are useless. Heart rate variability, tracked against an athlete's own baseline, can be a genuinely useful signal (Plews et al., 2013). But it does mean that when an athlete says "that felt harder than it should have," it's not a soft comment to be weighed against the "real" data. It is real data, and often the earliest data you'll get.
Why we lose it anyway
If subjective feedback is so valuable, why do coaches miss it?
Not because they don't care. Because of how it arrives:
- It's scattered. A comment in a group chat. A word after practice. A note in a training log. A text at 10pm.
- It's unstructured. "Legs are dead" and "I'm fine just tired" mean different things from different athletes.
- It's spread out over time. One comment is nothing. The same comment three times in ten days is a pattern. But you only see the pattern if you're looking at all three at once.
- It competes with everything else. You have 30 athletes, a practice plan, a meet on Saturday, and a parent email to answer.
Most coaches I talk to don't have a monitoring problem. They have a memory problem. The information was there. It just never ended up in one place at the same time as the coach's attention.
Treating check-ins as data
Here's what I think good practice looks like, with or without software:
1. Ask the same short questions every day. Sleep, soreness, stress, energy, and one open line: "anything I should know?" Consistency matters more than detail. You're looking for change against each athlete's normal, not a perfect score.
2. Read each athlete against themselves. A 6/10 for energy means something different from an athlete who always says 8 than from one who always says 5. Halson (2014) makes the point that monitoring is most useful when it's individual.
3. Keep the open-text comments. The numbers tell you something changed. The comment tells you why. "Slept 5 hours, bio exam tomorrow" is a completely different conversation from "my knee's been weird since Tuesday."
4. Look for repetition, not just spikes. A single bad day is normal. The same complaint three times in a week is the thing to catch.
5. Close the loop. If an athlete tells you something and nothing changes — not even a "thanks, noted" — they'll stop telling you. The check-in is only as good as the athlete's belief that you read it.
Where wearables fit
I'd put it this way: wearables tell you that something might be off. The athlete tells you what. The coach decides what to do about it.
When HRV drops and the athlete's comment says "slept 5 hours, exam tomorrow," you have a clear, explainable reason to make the session easier. When HRV drops and the athlete says they feel great, maybe you just keep an eye on it. Neither number nor comment should make the decision alone.
The question underneath
We spend a lot of money on devices that measure athletes. I wonder how many coaches would get more out of simply reading what their athletes already wrote — all of it, side by side — every morning.
What would you catch if you never lost a comment again?
This is the core idea behind athlete readiness monitoring in Matter: readiness, sleep, and wearables sit next to what each athlete actually wrote, read against their own baseline, so the coach sees who needs attention and why. More on our approach in Evidence and Methodology.
References
- Saw AE, Main LC, Gastin PB. Monitoring the athlete training response: subjective self-reported measures trump commonly used objective measures: a systematic review. British Journal of Sports Medicine. 2016;50(5):281–291.
- Plews DJ, Laursen PB, Stanley J, Kilding AE, Buchheit M. Training adaptation and heart rate variability in elite endurance athletes: opening the door to effective monitoring. Sports Medicine. 2013;43(9):773–781.
- Halson SL. Monitoring training load to understand fatigue in athletes. Sports Medicine. 2014;44(Suppl 2):S139–S147.
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