Who is Renato Canova
The short answer
Renato Canova is an Italian distance coach who has coached Olympic and world medallists and many of the world's fastest marathoners, mostly from Kenya and Ethiopia, and later national programmes in China and elsewhere. He is known for "specific endurance": training built around percentages of race pace.
Canova started as a coach in Italy and moved his work to East Africa from the late 1990s. His athletes have won medals from the 3000 m steeplechase to the marathon. He has written and spoken openly about his methods for years, which is why so much of modern marathon training borrows his language.
Specific endurance
Canova's core idea is that general fitness, a big aerobic base, is the foundation, but it is specific endurance that wins races. Specific endurance means being able to hold race pace for the race distance. You build it by running more and more volume close to race pace as the race gets nearer.
Canova built much of his method with Kenyan athletes in the Rift Valley. The weekly rhythm around those sessions is in how Kenyan runners train.
He describes training as a funnel. Early on, paces are spread wide: slow aerobic running and fast short work. As the race approaches, both ends move towards race pace, and the sessions get longer at 90 to 105 percent of it.