The runners also might be able to correct a condition observed in some highly trained athletes known as exercise-induced arterial hypoxemia. Top marathoners have such vast cardiac output — they are able to circulate their blood seven or eight times a minute through the lungs, Pitsiladis said — that while running at top speeds at or near sea level, some have experienced a decrease in oxygen saturation in their red blood cells.

“Not all elite athletes get that,” Pitsiladis said, “but some do. Typically it’s the better ones.”

He compared the hypoxemia to a bus traveling so fast that passengers did not have time to climb aboard and fill all the seats.

“This place may really help correct that,” he said, “because there is more oxygen coming in.”

Above the sea in this biblical landscape, cliffs at the edge of the Judean Desert flared red and then became as tawny as lions. Pitsiladis spoke excitedly. He would have to bring top athletes here and conduct the proper experiments, of course. But he was encouraged by possibility.

“We can come and do training and racing in an environment like this, and this is probably the best place on the planet to do it,” Pitsiladis said.

The temperature in winter could be accommodating, “and there’s more oxygen than anywhere else, and it’s flat,” he added. “What else do you want?”

At dusk at the Dead Sea, the sky turned the blue and orange of a gas flame. Marathoners are accustomed to racing in the morning. But some research suggested that athletes might perform slightly better in the late afternoon, when body temperature and hormone levels peak, muscles become more flexible and lung function is enhanced.

Pitsiladis had one final mission on his scouting trip: a run of five or six miles along dikes that jutted into the sea, bordering vast ponds where minerals were extracted.