What is negative split and why it makes you last longer

If you have run a race, you know that the last few miles are the hardest: your body is fatigued, your strength fails, the aches and pains take over.
It is normal for this to happen: running is an endurance sport, and because you practice it for prolonged periods it fatigues and burns energy.

It was the year 2007

Sept. 30, Berlin Marathon. Haile Gebrselassie crosses the finish line first. There is great anticipation to see what the weather will establish. Setting a record in Berlin is important because it is one of the fastest race-perhaps the fastest-in the world. World records are set in Berlin, and Haile does not disappoint: 2h04’26” (he will even better it in 2008).
What is even more surprising, however, is the regularity with which he ran: his intermediate times indicate that he ran like a train and with incredible consistency. But that’s not all: Haile ran the second half of the race in less time than the first: 1h01’56” versus 1h02’29”. In other words, he ran faster in the last leg than in the first.
When he was most fatigued and tested by the dozens of kilometers he had done, he not only maintained the regularity of the first part of the race, but even managed to accelerate.

The negative split

What Haile Gebrselassie did in Berlin was to use the negative split. We are not talking about a secret weapon but a technique of dividing the race into one or more parts and running the last part faster than the first. Haile ran the first part at a pace slightly below his average and the second at his average, accelerating in the final, from 35th onward. In fact, in the 40th he scored his best time: he had accelerated and not by a little.

“Splitting,” i.e., separating the race into several parts, has different declinations and does not always mean splitting it in half. What is important is that it teaches how to use energy intelligently. As you can also do in everyday practice or competition.

Why it is important to dose energy

Imagine that your body is the engine that makes you run. At first it will burn mostly sugars (glycogen). When these become scarce or depleted it will begin to burn fat. To do so, however, it needs oxygen, lots of oxygen. And it needs it at the same time that your muscles need it too. In short, the paradox is that to maintain your running pace you have to do two things: burn fat and push your muscles at the same pace as before. The longer you delay this the smoother and less strenuous your ride.

To sum up: you have an engine (the body) and gasoline (the glycogen). You can decide to push hard right away and go as far as you can, or you can decide to travel at a lower than top speed, consume just enough, and devote yourself to sprinting only at the end.

Okay, what if I don’t compete?

No matter. This technique makes sense in competitions but it also makes sense in training. How many times were you stressed or pissed off and started off at top speed only to find yourself panting on the side of the road after a few miles? You have mismanaged your energy. Maybe you don’t need to use refined gait calculations but simple common sense: never start off at full throttle, but choose two ways:

  1. Run the first half of the workout below threshold and the second half at threshold (at or about maximum)
  2. Progress: start slowly and speed up a little at a time. You can do it by feel (and breath ;) or with the help of GPS, always taking off a few seconds with each new kilometer.

A famous example

Steve Prefontaine, one of the world’s greatest athletes, used negative split. When in college, he was coached by Walt McClure, who introduced him to the technique, motivating him as follows: “First, it allows the runner to do the first part more relaxed and slower. Second, it allows him to build the self-confidence to have the ability to accelerate in the final stage“.
It worked great for Steve. What about you?

(Photo credits Curtis Mac Newton)


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