Negative Split: How to Run the Second Half Faster and Train It With Progression Runs
Running a negative split means running the second half of a race faster than the first. It is the strategy behind many records and the one that avoids the classic mistake of starting too fast and paying for it at the end. This guide explains what the data says, how to apply it in a race and how to train for it with progression runs.
What a negative split is
You divide the race into two halves and run the second one slightly faster. For example, in a 1:50 half marathon, you would run the first half in 55:30 and the second in 54:30. The opposite, starting fast and fading, is a positive split, and it is what most recreational runners do.
What the data says about race pacing
The study by Santos-Lozano and colleagues analysed the times of 190,228 New York City Marathon finishers. Every group ran the second half slower, but the fastest runners varied their pace the least. The authors conclude that keeping an even pace means avoiding an overly fast start that then forces a big slowdown.
At elite level, the analysis by Díaz and colleagues of marathon world records between 1998 and 2018 found that men set them with a negative split, speeding up as the race went on, while women held similar paces in both halves.
The practical takeaway for a recreational runner: the realistic goal is an even pace or a slight negative split. What costs the most time is starting too fast.
How to run a negative split in a race
- Start 5 to 10 seconds per kilometre slower than your goal pace for the first few kilometres.
- Settle into goal pace from the first quarter of the race.
- If you feel good in the final third, pick it up progressively.
- Do not try to make up in two kilometres the time you lost in a crowded start.
To find a realistic goal pace, use the race time predictor with a recent result.
| Distance | Opening | Middle | Finish |
|---|---|---|---|
| 10K | Km 1-3, 5-10 s/km slower | Km 4-7 at goal pace | Km 8-10, push if you can |
| Half marathon | Km 1-5, 5-10 s/km slower | Km 6-16 at goal pace | Km 17-21, push if you can |
| Marathon | Km 1-10, 5-10 s/km slower | Km 11-32 at goal pace | Km 33-42, hold or push |
In the marathon, a fast start has an extra cost: you burn glycogen too early and raise the risk of hitting the wall.
How to train a negative split: the progression run
A progression run is a run where you raise the pace in stages. It teaches you to control your start and finish strong when tired. Some examples:
- 10 km progression run: 4 km easy, 3 km at moderate pace and 3 km at half marathon pace.
- Long run with a fast finish: the last 20 or 30 minutes at marathon pace. There is more on organising it in the guide to the long run.
- Progression by feel: split the run into three parts and run each one a little faster than the last.
Do one of these sessions every one or two weeks as part of your quality work. If you are unsure of your paces, the guide on how to calculate training paces helps you work them out.
Common mistakes
- Getting carried along by the crowd at the start.
- Watching only your watch on hills instead of holding the effort.
- Trying for a big negative split. It is enough for the second half to be equal or slightly faster.
- Not practising it in training and trying it for the first time on race day.
Conclusion
A negative split means running the second half faster than the first. Men’s marathon records have been set this way, and in New York the fastest runners varied their pace the least. To apply it, start 5 to 10 seconds per kilometre slower, settle into goal pace and push at the end if you can. Train it with progression runs every one or two weeks.
FAQ
What is a negative split?
Running the second half of a race faster than the first.
Is a negative split better than an even pace?
For most recreational runners, an even pace or a slight negative split works best. What you must avoid is starting too fast.
How much slower should you start?
One reference is 5 to 10 seconds per kilometre slower than your goal pace for the first few kilometres.
What is a progression run?
A run where you raise the pace in stages, for example easy, moderate and fast. It teaches you to finish strong.
Does it work in the marathon?
Yes. Starting a little slower helps save glycogen and lowers the risk of hitting the wall in the final kilometres.
