But now that the most decorated Olympian of all time has moved on to fatherhood and coaching full time, Phelps is relishing his distance from the demands of world-class swimming. He's down to 190 pounds, and he's trying a new workout plan, one that, over a recent 30-day stretch, helped him burn only 28,000 calories.
"It's all I do. I pound it. I went 30 straight days on the bike," he told NBC Sports last week, before enumerating his monthlong statistics a devotee of the indoor exercise bike company Peloton: 500 miles in 30 days, 1,100 minutes on the bike and the nearly 30,000 calories burned off. "I was just basically at the point I just was like, I'm just going to grind for a month and see what happens. Somebody said, what are you going to do after that month? Probably keep going. I like having that competition on the bike. I ride a Peloton, so I ride in classes. I have an alias. No one knows it's me."
Phelps isn't a world-record holder in Peloton competition, at least not yet. He told NBC Sports that he finishes in the top 5 to 10 percent of races "every single time I'm in there." Which is quite often, apparently. He exercises nearly every day of the week, and on the day of his interview had gotten up at 5:15 a.m. for a workout.
"The biggest thing for me now being retired, I know how important it is for me to get that energy out, to be the best version of myself," he said.
At this point, it sounds as if Phelps is closer to breaking into competitive cycling than he is to returning to competitive swimming. He said he'd like to pack some more muscle on, but pointedly told NBC Sports, "I'm still not getting back [to competitive swimming], so don't ask."
But as for races that aren't underwater?
"If I could do a triathlon and not do the run, I would instantly do it," he said. "Swimming is easy. I still swim a couple of times a month just to get in and splash and see the sun, but I don't think so [cycling]. I would get my [butt] kicked on the bike. Some of those guys are ridiculous on the road. I wanted to start riding on the road, but I'm not going to get the kind of resistance that I get on my stationary bike. The workout's going to be different. I love what I do, to be able to sit and take 45 minutes to 90 minutes to be able to get a workout in, get a bike in, to stretch, do some abs outside and call it a day, I'm good."