The large portion of successful businesspeople involved in endurance sports isn’t surprising, considering the personality traits they tend to share. These, says Dr. Michael Sachs, a sport psychologist at Temple University, include “high levels of motivation, goal orientation, mental toughness. They also realize that in order to be successful, they need to maintain physical and mental health, and one of the best ways to do that is exercise.”

In addition, he says, there’s a “coolness” factor. “If you’re wearing a Boston Marathon T-shirt or an Ironman finisher’s jacket, those are credentials you can’t buy. You have to earn it.”

Ironman distance triathlons are not the only events that attract Type A endurance athletes. In the last five years, Jeff Adams, 56, a retired Morgan Stanley executive living in Elkhorn, Wis., has run in 20 marathons around the world, including New York, Boston, London, Tokyo and even Antarctica.

Mr. Adams estimates that his pursuit of running and fitness — including the cost of travel to his various races, his gym memberships and so forth — has cost him $50,000 a year over the last five years. But he ticks off what he calls his “return on my running investment,” including improved health, weight loss and the opportunity for adventurous travel.

Women, even successful women, are less likely to be found jetting around the globe or spending significant amounts of money in pursuit of their training and racing goals. “I don’t know many women who are high powered and wealthy and who are also endurance athletes who would go to these extremes,” says the former professional triathlete Lee DiPietro, 57, of Delray Beach, Fla., and author of “Against the Wind: An Ironwoman’s Race for Her Family’s Survival.” But she said that could change.

For his costly 2013 effort, Mr. Blumencranz dutifully did all his training leading up to Kona, the pinnacle of swim-run-bike sport — a one-day 2.4-mile swim, 112-mile bike ride and 26.2-mile marathon through the island’s torrid, wind-swept lava fields. Qualifying was difficult: Although he had twice completed the Ironman distance race in Lake Placid, N.Y., Mr. Blumencranz is not an elite athlete.