Heat training is the legal performance hack that's transforming professional cycling—and it might be sitting in your garage right now. By deliberately raising your core temperature to 38.5°C for just a few weeks, you can gain 3-4% in hemoglobin mass, boost your VO2 max by 6%, and add 20-30 watts to your FTP. We'll break down the science behind why this works, show you exactly how the pros are doing it, and give you a step-by-step protocol you can implement at home.
Key Takeaways
- Heat training increases hemoglobin mass by 3-4% in 5 weeks—equivalent to months of altitude exposure—and can add 20-30 watts to FTP
- The key protocol: raise core temperature to 38.5°C and hold it for 30-40 minutes, 3 times per week for 14 days; adaptations begin in week one but full benefits appear after two weeks
- Heat training locks in altitude gains for 3.5+ weeks, whereas the control group lost almost all benefits—making it ideal for extending altitude camp benefits before a race
- Nearly all World Tour teams now use heat training; 17 of 21 Tour de France stage winners in 2024 were core temperature sensor users
- Passive heat exposure (40°C hot baths for 20-45 minutes) produces similar adaptations to active heat training and may be more practical for home use
- Safety is critical: stop immediately if core temperature exceeds 39°C, and don't lose more than 2% body weight per session; use electrolyte drinks, not plain water
Expert Quotes
"Heat training effectively locked in and extended the benefits of altitude training... Heat training maintains increased hemoglobin mass while the control group lost almost all their gains."
"Increasing hemoglobin mass by 3 to 4% through heat training is the equivalent of months of altitude exposure. That's a huge return on investment for just a few weeks of sweating."
"Heat adaptation isn't just about surviving hot stages. It improves aerobic efficiency even in cool weather. In other words, you get fitter in all terrain, in all weather by training in heat."