You've optimised everything. Except your breathing.
HYROX, marathon, ultra-running, cycling, swimming, triathlon. If training, nutrition and recovery are already dialled in and you're still leaving performance on the table, breathing efficiency is usually the lever nobody's trained.
BOLT doesn't automatically improve as fitness does. It responds to targeted training in weeks, not seasons — and it directly affects your performance ceiling under load.
Fitness doesn't guarantee efficient breathing
Your BOLT score reflects breathing efficiency and CO₂ tolerance — how well you handle the build-up of carbon dioxide that drives the urge to breathe under load. It's a different metric to VO₂ max, FTP or pace, and it doesn't automatically improve as those do.
Body Oxygen Level Test
Trained and tracked like everything else in your program
Baseline
We take your BOLT score and look at how you're actually breathing under load — nasal or mouth, chest or diaphragm, what happens when effort spikes. If you have race data or threshold tests, we pull those in too.
Targeted training
Nasal breathing at easy pace, CO₂ tolerance work, and breath patterns matched to your sport — transitions in HYROX, climbs on the trail, position changes on the bike, bilateral breathing for swimmers.
Re-measure
We re-test your BOLT score and set it alongside your training data — threshold pace, FTP, station splits, race times, HRV. You see what moved and by how much.
BOLT testing and CO₂ tolerance work should only ever be practised at rest, seated or lying down, in a safe environment. Never practise breath-holding while driving, cycling on the road, or during any activity where losing focus would be dangerous.
Swimmers: breath-hold practice combined with swimming carries a real risk of shallow-water blackout. Any in-water breathing work happens in a supervised squad setting — never solo.