IRONMAN is the race format where altitude training matters most. Eight to seventeen hours of continuous output is decided by efficiency. Hbmass and oxygen utilisation are the metrics that translate most directly to finishing time over that duration.
Most IRONMAN-focused altitude protocols use longer, lower-set-point blocks than shorter-distance racing.
A typical IRONMAN altitude block runs 4 to 6 weeks at 2,200 to 2,500m (7,218 to 8,202ft) for 8 to 11 hours per night, timed so the Hbmass peak lands 2 to 4 weeks before race day. The block stacks on top of normal high-volume IRONMAN training. Training intensity stays at sea-level wattages and paces. Recovery between long sessions improves measurably across the block.
For athletes preparing for IRONMAN World Championship qualification or Kona campaigns, multi-block protocols across the year are common. Cameron Wurf runs altitude blocks between road racing and IRONMAN seasons to maintain physiological adaptation across both disciplines without taking either off the schedule.
For more on how camps and home altitude integrate, read about altitude training camps.