Negative splits vs even pacing: what the research says
A negative split means running the second half of a race faster than the first. An even pace holds the same speed throughout. A review of pacing research found that in events longer than about 2 minutes, distributing pace more evenly may improve times. It did not show that a negative split beats an even pace.
What the terms mean
- Even pacing: the same pace for the whole race.
- Negative split: the second half is faster than the first.
- Positive split: the second half is slower than the first.
Splits are the times you record at set points, such as every mile or kilometer. The mile pace calculator and the race pace calculators list the split times for an even pace.
What the research says
Abbiss and Laursen reviewed pacing strategies across athletic events. Their main points:[1]
- Very short events of about 30 seconds or less may suit an all-out start.
- In prolonged events longer than about 2 minutes, performance times may improve if athletes distribute their pace more evenly.
- The best strategy for middle-distance events of 1.5 to 2 minutes and for ultra-endurance events longer than 4 hours is not well established. Well-trained athletes in those events tend to slow progressively after reaching peak speed.
- The limits of aerobic and anaerobic energy supply seem to shape the best strategy.
Almost every road race from the 5K to the marathon lasts well over 2 minutes, so the review points toward a steady effort. It does not claim a negative split is faster than an even pace.
Planning the splits: a 4:00:00 marathon example
The table shows three plans for the same 4:00:00 finish. A 2% negative split means the second half takes 2% less time than the first. The paces are per mile.
| Plan | First half | Second half | First-half pace | Second-half pace |
|---|---|---|---|---|
| Even pace | 2:00:00 | 2:00:00 | 9:09 | 9:09 |
| 2% negative split | 2:01:13 | 1:58:47 | 9:15 | 9:04 |
| 2% positive split | 1:58:49 | 2:01:11 | 9:04 | 9:15 |
The even plan needs 9:09 per mile throughout. The negative plan asks for a slower start and a faster finish, and the positive plan does the reverse. Get your own numbers with the marathon pace calculator.
When to depart from an even pace
- Hills. An even effort on a hilly course gives uneven pace. Climbs are slower and descents faster.
- Wind and heat. Both raise the cost of a given pace, so hold back early if conditions are hard.
- A crowded start. Early miles can be slower because of congestion. Check your elapsed time against the split table and adjust gradually.
These are practical points, not findings from the review.
How to use the calculators
Choose your distance: 5K, 10K, half marathon or marathon. Enter a goal time and read the kilometer and mile splits. If you do not have a goal, estimate one with the race time predictor.
Frequently asked questions
Is a negative split faster?
The research review did not show that. It found that for events longer than about 2 minutes, distributing pace more evenly may improve times. A small negative split can still be a sensible plan if it helps you start under control.
What is an even split?
An even split means every mile or kilometer takes the same time. For a 4:00:00 marathon, that is 9:09 per mile.
Does pacing matter in a 5K?
Yes. A 5K lasts well over 2 minutes for almost every runner, so the review’s finding about even distribution applies. Use the 5K pace calculator to see the time you should have at each kilometer.
Sources
Related tools and guides
About the author
Shaheer Bin Ramzan is a software engineer and SEO specialist with five years of professional experience. He builds and checks the calculators and writes the guides on MilePaceLab. He is not a running coach or doctor. See the author page, the methodology and the disclaimer. Report errors through the contact page.