Do pros swim at maf during ironman races?//

Not even close. Most pros are red lining the swim, and even the guys on the front are swimming way more than MAF speed. In fact, they don't race any of their races at MAF speed, i believe he advocates this all for training, not racing.

You are correct - MAF is a training method. I swim 40% of my swimming at IM distance pace. I train bike and run at MAF. I will sprinkle in some MAF run repeats at +10 to 20 bpm on some 2km repeats when I get about 60 days out 1x/week. On race day, I will swim a bit more than MAF, I will ride at MAF + 5 roughly and do my very best to manage my HR and cadence on the run (easier said than done). So many factors: heat, wind, course conditions (coefficient of friction if you will), humidity, hydration, electrolytes, nutrition and on and on....oh yeah, fatigue. good thread - thx

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- the Lone Wolf