Green, yellow, red.
How to use HRV, sleep, and stress to decide how hard to train today, so you recover, keep progressing, and stop guessing.
The short version
- HRV (heart rate variability) is a window into how recovered your nervous system is.
- Compare HRV to your own baseline, never to other people.
- Combine HRV, resting heart rate, sleep, and how you feel into a simple green, yellow, or red day.
- Green: push. Yellow: train, but pull back. Red: recover.
What HRV actually is
Your heart doesn't beat like a metronome. The time between beats varies slightly, and that variation is your heart rate variability. It reflects the balance between your "rest and recover" and "fight or flight" systems.
- Higher than your normal: generally a sign you're recovered and ready for stress.
- Lower than your normal: your body is dealing with something: hard training, poor sleep, alcohol, illness, travel, or life stress.
HRV is very individual. A "good" number for one person might be low for another. Age, genetics, fitness, and the device you use all change it. That's why your own baseline is the only comparison that matters.
The four signals to check each morning
| Signal | What to look at |
|---|---|
| HRV | Today vs. your 7-day average and your normal range (most apps show this) |
| Resting heart rate | Several beats above your normal can signal fatigue, illness, or dehydration |
| Sleep | Hours and quality. Under about 6 hours makes a hard session much less productive. |
| How you feel | Energy, soreness, mood, stress, on a quick 1–5 scale |
Devices like WHOOP, Oura, Garmin, and Apple Watch all measure HRV slightly differently. Stick with one device and measure the same way (usually overnight) so your numbers are comparable.
The green, yellow, red system
| Day | What you see | What to do |
|---|---|---|
| Green | HRV at or above normal, resting HR normal, slept well, feel good | Train as planned. This is the day for heavy sets, new personal bests, and hard conditioning. |
| Yellow | HRV somewhat below normal, OR resting HR up a few beats, OR short sleep, OR feeling flat | Train, but pull back. Keep the main lifts, drop a set, stay 2–3 reps from failure, skip the hardest conditioning. |
| Red | HRV well below normal AND resting HR elevated, very poor sleep, or feeling sick | Recover. A walk, mobility, breathing work. Rest is training today. |
Rule of thumb: one bad signal = yellow. Two or more bad signals, or feeling sick = red.
What to do on a yellow day
- Do the warm-up, then decide. Many yellow days turn green once you get moving.
- Keep the first one or two main lifts, cut the volume after that
- Swap high-intensity intervals for steady, easy cardio
- Add 5–10 minutes of slow breathing or mobility at the end
What to do on a red day
- 20–40 minutes of easy walking, preferably outside
- Gentle mobility for hips, upper back, and ankles
- Slow breathing: try 5 minutes of breathing in for 4 seconds and out for 6
- Prioritize sleep, hydration, and a solid protein intake
Two or three red days in a row? Look at the cause. Is it training, sleep, stress, alcohol, or are you getting sick? If you feel unwell, check in with your doctor.
Mistakes to avoid
- Chasing a daily number. HRV bounces around. Weekly trends matter more than any single morning.
- Letting the app overrule common sense. If you feel great and the data is borderline, a normal session is usually fine.
- Making every day a red day. Some fatigue is part of training. The goal is to manage it, not avoid it.
- Comparing with friends. Your baseline is yours alone.
Common questions
What's a good HRV?
There isn't one universal number. A rising trend over weeks, alongside training progress, is a good sign. A falling trend is worth investigating.
Do I need a wearable?
No. Resting heart rate on waking, sleep, and a quick 1–5 rating of energy, soreness, and stress work well on their own. A wearable just makes it easier and more precise.
Why is my HRV low after drinking?
Alcohol is one of the most reliable ways to lower HRV and raise resting heart rate overnight. It's often the clearest pattern people find in their data.
Training that adjusts to your recovery.
Every MB Online plan includes a daily 30-second readiness check in the MB app. Your green, yellow, or red day adjusts that session automatically, so you push when you can and recover when you need to.
This guide is educational and is not medical advice. It does not diagnose, treat, or replace care from your physician. Talk to your doctor before starting a new exercise program, especially if you have a medical condition. Wearable data is not a medical device reading. If you have chest pain, unusual shortness of breath, dizziness, or palpitations, stop exercising and seek medical care.