They also run an Ironman every year in Arizona
There's no such thing as a pretty good aligator wrestler.
A much more elite athlete trains for an Ironman than does for the marathon. An Ironman runs the marathon, then swims and bikes.
He just jumped in the water for the first time during the triathlon? I find that hard to believe. Even if that's true, your brother is not the norm, and he must have at least trained the running and biking parts. An Ironman athlete is generally a more elite athlete and in better condition than most amateur marathoners, which is, for the most part, who runs the Chicago Marathon.
Ditto, my son. He had done tons of long distance bike work going back to high school, as a supplement to his distance training. It was the swimming where the rubber met the road for him. It was clear that unless he was willing to do heavy training work in the water, he was not going to be a serious triathete even if he could achieve a fairly good overall finish. He realized that and chalked it up as a fun experience.
