Perna believes Phelps would have been weight training three times a week, and swimming up to 80 km every week while preparing to compete. So for one day, in his 12-meter pool, that means Perna will be doing 952 laps. Phelps' diet during this training would also be huge; around 8,000 calories worth of food per day.
To make the challenge even more difficult, he chooses to do it on a particularly chilly day — something which should not be attempted, as it increases the risk of developing hypothermia. "I literally thought I might die," he says, and so he has to pause the challenge while he sources a wetsuit.
After swimming a few laps to work up an appetite, Perna eats his first meal of the day: 3 fried egg sandwiches, 3 chocolate chip pancakes, 3 slices of French toast, a 5-egg omelette, and porridge, all of which equals around 2,900 calories. "I have not earned this breakfast at all," says Perna as he tucks in.
After completing 200 laps, and observing that he is getting a "pretty decent shoulder pump," it's time for lunch: half a kilo of spaghetti, 2 ham and cheese toasted sandwiches, and a few cans of energy drink, amounting to another 1,600 calories. (The credibility of this Phelpsian diet does look increasingly spurious as the day goes on.)
"I don't think I'll be able to complete the entire amount today," Perna says after lunch. "I am dead. I'm actually very, very tired. My shoulders feel like they're not cooperating any more, and I really want this to end. The last thing I want to do right now is go back in that pool."
1 hour 45 minutes later, he's completed another 150 laps, bringing his grand total up to 350 of the planned 950. "My body is not cooperating any more," he says. "I knew at around 200 that I couldn't get this done... But I still wanted to push to the point where I can't do any more, and that's where I'm at now."
But the challenge isn't over there. Perna still has dinner to get through: another half kilo of pasta and a whole pizza (2,500 calories, bringing his total for the day up to 7,000).
"My rotator cuffs were completely cooked, I've never felt that much pain," he says the next day. "But I guess it goes to show that was stupid of me to even think I could come close to doing that much swimming when I've never swam for more than 50 meters consecutively... Maybe next time, in hindsight, it would have been smarter to build up to that."
This article originally appeared on Men's Health US.