Your HRV isn't low. It's low for you.
Why a one-size-fits-all recovery line can't read your nervous system — and what we measure instead
2026-06-24 · 5 min read · Brevet · AI-assisted
Drafted with AI assistance and reviewed by a human. The science is sourced and real; the article isn't medical advice.
The short version: Heart-rate variability is one of the most personal numbers your body produces — two healthy riders can sit 30 points apart. So a fixed "good above X" threshold, the kind most apps draw, is reading the wrong book. We don't compare your HRV to other people. We compare it to you, last week and last month, and only speak up when it drifts outside your own range.
The number that means nothing on its own
Two riders roll up to the same group ride. One has a morning HRV of 95. The other, 48. Same age bracket, both fit, both sleeping fine.
A lot of apps would paint the first one green and quietly worry about the second. They'd be wrong about both. That gap isn't fitness or recovery — it's genetics, age, breathing, how the sensor sat on the skin. Heart-rate variability is the spread between your heartbeats, a peek at the nervous system idling underneath. Healthy people vary enormously. A 48 that's normal for you tells a completely different story than a 48 for someone who lives at 95.
Which is the whole problem with a fixed line. "Good above 60" is a sentence with no subject. Above 60 for whom?
Why the population line fails you twice
Draw one threshold for everybody and you get two failures, pointing opposite ways.
If your HRV naturally runs high, the line sits far below you. You could slide well off your own baseline — a real signal that today is different — and still clear the bar. The app says "fine" on a day your body is clearly asking for less.
If your HRV naturally runs low, the line sits up around your normal. Now you're flagged most mornings for no reason, until you stop looking. Either way the number stops meaning anything, because it was never calibrated to the only person it's about.
What we actually compare it to
Here's the reframe, and it's almost embarrassingly simple: the only honest comparison for your HRV is your own recent history.
So that's what we build. We learn your personal baseline from your own mornings, and we learn how much you naturally bounce around night to night — because a rider who swings 10 points daily and one who barely moves need very different goalposts. Then we draw a band around your baseline scaled to your swing, not a number copied from a textbook. A reading inside the band is an ordinary day. A reading that drops below it is what we'd call unusual for you — worth a glance, not a verdict.
One detail we're picky about, because it's a quiet way to be wrong: there are two common ways to compute HRV (RMSSD and SDNN), and they live on different scales. Mixing them silently is how you manufacture a "drop" that's really just a change of math. We tag which one a reading is and only ever compare like with like.
The part where we say "not yet"
The honest catch with a personal baseline is that you have to earn it. For your first couple of weeks, we mostly don't show you an HRV verdict — because we haven't watched you long enough to know your range, and any band we'd draw would be a default plus sensor noise wearing a confident face. Most apps hand you a recovery colour on day one. We'd rather say "still learning you" and mean it.
And even once the band exists, one morning is a whisper, not a sentence. HRV is noisy — a late meal, a hard pillow, a couple of drinks, the strap a centimetre off all move it. So a single dip nudges the picture; it doesn't define it. The signal worth trusting is the trend: several days leaning the same way, together.
A flag, never a diagnosis
When your HRV does sit below your band for a stretch, here's exactly what that means and what it doesn't. It means today's reading is outside your usual range — that's a description of your data, full stop. It does not mean we know why, and we won't pretend to. It could be a hard block landing, a short night, travel, a stressful week, or nothing you'll ever pin down.
So we treat it as information for tomorrow, framed as a suggestion you can wave off: maybe an easier session, maybe the planned one anyway. You always make the call, in one tap, and we log that the choice was yours. The number's job is to inform you, never to overrule you.
The thing we'd want you to take away is short, and it's the opposite of the dashboard reflex of comparing yourself to everyone else:
Your HRV isn't high or low. It's high or low for you — and that's the only comparison that carries any weight.
Read against the field, your nervous system looks like a stranger's. Read against your own last month, it starts telling you the truth.
A note on what this is
Brevet is a training and coaching tool, not a medical device. It does not diagnose, treat, or predict any medical condition. Heart-rate variability is used here only as a training signal, described relative to your own history — never as a health assessment. A reading outside your usual range is a prompt to consider an easier day, not a finding about your health. You make the final call on every session; the platform recommends, you decide.
Our methods are written up in plain language on the Science page — we believe a sceptical sports scientist should be able to read exactly what we do, and where the limits are.