The BOLT test
Body Oxygen Level Test: after a normal exhale, hold your breath until the first definite urge to breathe in. Untrained: 10–20 seconds. Trained endurance athletes: 30–50 seconds.
Why it matters in racing
Higher CO₂ tolerance means you can sustain race pace at a lower breath rate, with less perceived effort. The breathlessness threshold shifts.
The weekly protocol
Three sessions a week. Each: 10 cycles of normal breath then exhale-and-hold to first urge to breathe, with 30 seconds normal breathing between. Build to 5 cycles of inhale-and-hold to add variety.
What changes in race performance
After 8 weeks of consistent practice, expect a 5–10 second BOLT improvement, lower race heart rate at the same pace, and easier breath recovery between intervals.
Log your sessions in Breathe On and explore the matching guidance at [/breathing-for/athletic](/breathing-for/athletic).