Dr Andrew Sellars has spent 35 years studying why cyclists blow up on hard efforts. His answer: it's not your legs, it's not your heart. It's your breathing. And the French study he references on this episode of the Roadman Cycling Podcast showed pro cyclists improving FTP by 6% over 48 weeks purely through respiratory training protocols.
Key Takeaways
The main thing Sellars told me that I hadn't heard before is that CO2 drives your breathing, not oxygen. The harder you ride, the more CO2 you produce, and your body has to breathe faster to blow it off. Your blood oxygen level barely moves. Which means when you can't hold your power on a hard effort, your breathing system may have given out before your legs did. Sellars says most athletes have never trained this system at all, which means there's a meaningful gain sitting there untouched.
The protocol from the French study Sellars references ran 48 weeks and broke down into six-week blocks: diaphragmatic breathing and nasal breathing first, then coordination work, then resistance training, then aero-position-specific breathing. The pro cyclists in that cohort increased tidal volume from 6.5L to 7.7L, a 10% improvement, and averaged 6-8% FTP gains. Sellars also says nasal breathing stimulates the opposite hemidiaphragm, so breathing through your right nostril activates your left hemidiaphragm, which increases diaphragmatic involvement compared to mouth breathing. And slower breathing improves HRV by allowing greater cardiac stretch between beats, which is why Marco Altini says breath control during HRV measurement is so important.
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If you want to understand how HRV actually works and why wrist-based devices give you bad numbers, go listen to the Marco Altini episode. And if your heart rate is running higher than expected at a given power output, the five fixable reasons episode is worth your time.