The farrago of a sport that is the modern pentathlon owes its rarefied existence to Pierre de Coubertin, the father of the modern Olympics, who, according to legend, imagined it as a test of mettle for a typical French cavalry officer. Caught behind enemy lines, such a man might have to fence with and shoot at his pursuers; run toward safety; swim across a body of water; and ride away on a random horse he happened to encounter.

But many things that made sense in the 19th century seem less persuasive in the 21st. So, drifting toward obsolescence and facing eviction from the Olympics after an accusation of horse abuse in the Tokyo Games, modern pentathlon’s governing body voted in 2021 to overhaul itself for the contemporary era.

While the pentathletes at the Paris Games are indeed riding horses over a series of jumps as part of the event, they will face an entirely different fifth discipline when they get to Los Angeles in 2028: a race the organizers are calling a “‘Ninja Warrior’-style obstacle course.”

Officials said that this bracing change to a niche sport that wafts vaguely into public consciousness every four years, only to waft out again, was a matter of urgency.

“We had to reduce its cost and improve its accessibility, ” Klaus Schormann, the president of modern pentathlon’s governing body, known as the U.I.P.M., said. Shiny Fang, the group’s secretary general, called the updated lineup “perfect for the TV audience.”