Stress · 4 min read ·
Your watch says low recovery and you slept well. That number needs several days to read properly.
If you have 30 seconds
- 1HRV is heart rate variability. When it's higher than your usual, you've generally recovered well.
- 2It can drop with alcohol, late dinners, tension, too much training or a bug on the way.
- 3Read the trend over several days, never a single morning.
You wake up feeling fine and your watch says low HRV, low recovery. What does low HRV mean when you've slept right through?
The people I work with often ask me this. You and the watch are looking at different things, and you can both be right.
What does low HRV mean?
Most often it means your nervous system recovered less than usual last night. One morning like that happens to everyone and usually says nothing about your heart's health.
HRV stands for heart rate variability. At rest your heart doesn't tick like a metronome. The gap between beats is slightly different each time, by thousandths of a second. HRV measures how much it changes.
As a rule, the more it varies, the better. Two systems control your heartbeat. One speeds it up, one slows it down. When the brake works well the beat is springy and keeps adjusting. After weeks under pressure the accelerator tends to win and the rhythm stiffens. Picture a child jumping about, then someone too stiff to move easily.
What lowers HRV, even when you sleep well
The causes of low HRV often lie in the day and evening before. You can sleep your full hours with your body still revved up.
- Alcohol in the evening. You drop off sooner, but your heart rate tends to stay high overnight.
- A heavy, late dinner. Digestion can keep your body switched on when it should be slowing down.
- Hard training late in the day. Adrenaline and body temperature go up, and take time to settle.
- A head that won't switch off. A thought on a loop is work for your body, even in bed.
- Something you're coming down with, or too much training. The number can fall before symptoms, and after weeks without a break.
The number is about how rested your nervous system is. Hours slept are a separate matter.
What to do about low HRV
Look at the trend. Open the multi-day view, a week or so. One low night counts for little. Several in a row start to tell you something.
Leave other people's numbers alone. No number is good for everyone. It varies widely between people, and two devices worn together give different figures. What matters is how far you drift from your own average.
Check it against your resting heart rate. If that's higher than usual in the morning and your variability is lower, your body probably hasn't recovered. Ease off that day. Walk, or keep the session and lighten the load.
Look for the cause in the evening before. Wine, dinner time, training, tension. Change one thing at a time and see whether the line climbs over the next few days. That's how you learn what affects you.
Trust the right data. These devices read heart rate, variability and hours slept reasonably well. Sleep stages, deep and light, are estimates, so watch the trend.
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Test yourself
Your watch shows low recovery, you feel fine and you're due to train. What do you do?
Give it a few weeks before drawing conclusions. If the number falls after tense evenings, the evening is where the work is. I cover that in the articles on cortisol and switching off from work.
