Negative Split

A negative split means running the second half of a race faster than the first. It is widely regarded as the most efficient way to race distance events, from a 5k to a marathon, because it conserves glycogen and limits the early lactate build-up that comes from setting off too hard. Start controlled, finish strong, and you reel in runners who blew their pacing in the opening miles. Almost every world record in the men's and women's marathon has been run on a near-even or slightly negative split, which is why elite pacing is obsessive about not banking time early. The psychology is harder than the physiology: it feels wrong to hold back while fresh when everyone around you is surging. But the runner who negative-splits is the one still accelerating when others are merely hanging on. For pacing guidance grounded in the physiology, Coopah's pacing guide breaks down how to build the habit. The opposite — fading badly over the back half — is a positive split, and it is the single most common amateur racing mistake.