Free · Takes about 5 minutes
Test your BOLT score
A simple, comfortable breath hold that shows how sensitive your body is to carbon dioxide. That sensitivity shapes how you breathe all day, and can affect your sleep, mind, energy and recovery.
What is the BOLT?
Every breath you take is triggered by carbon dioxide building up in your blood. It's your body's main signal to breathe, even more than oxygen.
When your body is overly sensitive to that build-up, the signal comes early and strong. Your breathing becomes faster and harder, often higher in your chest, and you can feel like you never quite get a satisfying breath. That same pattern follows you into your sleep and your workouts, and faster, harder breathing can keep your body in a stress response.
The Body Oxygen Level Test (BOLT) shows you where you are. You breathe out normally, gently hold your breath, and time how long it takes until you feel the first definite urge to breathe. That's roughly how long it takes your brain to react to the fact that you've stopped breathing.
A shorter time usually means your body is more sensitive to carbon dioxide, and your everyday breathing tends to be faster and harder. A longer time means better tolerance, and lighter, calmer breathing.
You're not trying to hold on for as long as possible. When you start breathing again, it should feel normal.
It isn't a measure of fitness. It's an indicator of your everyday breathing, your sleep and your recovery, and you can repeat it as you practise to see your progress.
Take the test
- Sit upright and breathe normally through your nose for 3 to 4 minutes. Don't try to change your breathing.
- When you're ready, take a normal, quiet breath in through your nose, then let a normal breath out. Don't push the air out.
- Straight away, pinch your nose and tap Start.
- Tap Stop at the first clear urge to breathe, or when you feel your breathing muscles start to twitch or pull. Don't push through. This isn't about how long you can hold your breath; it's about when the urge first shows up.
Your breathing should feel normal when you start again. If you need to gasp or take a big breath, you held on too long. Rest for a few minutes and try again.
This test is educational and isn't medical advice. If you're pregnant, have a medical condition, or are under 18, please check with your doctor before practising breath holds.