Negative Split

Running the second half of a race faster than the first — a sign of disciplined pacing.

negative splitpacingsecond halfstrategy

Understanding Negative Split

A negative split means running the second half of a race faster than the first half. It's widely considered the optimal pacing strategy for distance races, and nearly every marathon world record has been run with an even or negative split.

The physics are simple: if you go out too fast, you accumulate lactate and burn through glycogen stores prematurely. By starting conservatively and building into the race, you preserve fuel for when it matters most — the final miles where most runners slow down. Running a negative split when everyone around you is fading is one of the best feelings in racing.

Executing a negative split requires discipline and self-awareness. The first miles of a race feel effortless because of adrenaline, cool muscles, and fresh glycogen. The temptation to bank time is strong. Experienced racers know that "banking time" early almost always costs more time in the back half than it saves.

Key Facts: Negative Split

Key facts and insights about negative split that every endurance athlete should know.

Eliud Kipchoge ran negative splits in hi

Eliud Kipchoge ran negative splits in his 2:01:09 marathon world record

Studies show most recreational runners p

Studies show most recreational runners positive-split races by 5–10%

Even splits

Even splits (both halves within 1–2% of each other) are nearly as effective as negative splits

Negative splitting is hardest in the mar

Negative splitting is hardest in the marathon and easiest in the 5K due to distance and fatigue factors

Pro Tips: Negative Split

In the first mile, check your watch and deliberately slow down if you're ahead of goal pace

Run the first half at goal pace, then try to pick it up slightly in the second half

Practice negative splitting in training runs — run the second half of easy runs 10–15 seconds per mile faster

Use landmarks or mile markers to create mental "gears" — shift up as the race progresses

Frequently Asked Questions About Negative Split

For most distance races (10K+), yes. For shorter races like the 5K, even splits are fine. In tactical championship races, splits matter less than position. And in trail races with varying terrain, effort-based pacing makes more sense than split-based pacing.

Aim for 1–3% faster — roughly 5–15 seconds per mile in a marathon. Going 5%+ faster in the second half usually means you went out too conservatively. The goal is controlled acceleration, not a dramatic shift.