Running Negative Splits: Run Slower To Be Faster

Updated: Aug 29, 2019



Pentons Performance Therapy clients looking focused on their way to 1st and 3rd at last years Cheltenham Half Marathon

How does running slower mean running faster? That’s the idea behind running negative splits, it doesn’t necessarily mean starting off slow, the key is to finish fast, or at least faster. Eluid Kipchoge broke the marathon world record in Berlin using negative splits, his second 13 miles were over 30 seconds faster than his first 13 miles. Fig a below shows Mo Farah’s split times for his 10K world champs win in London 2017.


So why is this better than to run at your limit and then try to hold on to the finish?

There are numerous reasons why this works and why you should be training to race on negative splits. Physically and psychologically this method of running can and will help you smash your PBs over whatever distances you are running from 5K and above.


Enables the body to warm up fully and operate at its most efficient


Warming up before any physical event is essential, and although perhaps we could be better at warming up most of us believe we are sufficiently warm and ready come race time. However, there is usually a delay between finishing a warmup and beginning the race meaning the heart rate begins to slow, the muscles begin to cool down and the body is no longer ready to dive straight into sub-maximal work. Setting off at a sensible pace allows the body to get back to optimal performance meaning when you need to kick towards the end of the race your body is in the best physical place to do this.

Avoid the dreaded bonk or survivors shuffle


Setting out hard, running on or below PB pace and then clinging on for grim death feels like the best way to go about things because it is so hard. This is because the body starts to accumulate Lactic Acid (or more precisely Hydrogen), read our blog on The Energy Systems for Endurance Athletes to find out why this is the case. When this builds in the muscles and blood lactate levels rise too high the body has no choice but to slow down. Lactate levels will rise higher quicker when the body isn’t fully warmed up thus supporting point 1. A build up of blood t causing the burning session in your muscles and the lungs must work overtime to try and get more oxygen in and carbon Dioxide out to readdress the balance.

Gives you the tactical edge

Running negative splits means you should be comfortable and in control for the first half of the race. This in turn means you should be able to focus on race tactics, think through your plans and not make mistakes due to fatigue. Most importantly it gives you the upper hand in the penultimate stages of the race. If all your rivals have ran themselves into the ground, they will not be able to attack you or respond to changes in pace. It’s a must nicer feeling passing people than being passed.


Train for and trust the process to succeed

As most runners tend to be a competitive bunch, intentionally setting off behind PB pace seems stupid at best. But the key is to trust the process, you must know that you will be able to gain back time towards the end of the race. Practice this in training runs so you know it works. By saving precious fuel for work come the end of the race you can and will see your pacing drop towards your target/PB. Progression runs, fartlek training, park runs are all great ways to perfect this skill. Negative split running is as much about mental toughness and discipline as physically training the body to do it.


So how fast is too fast and how slow is too slow?

There are many very scientific ways to establish this, things like Lactate Blood testing, to find exactly how hard the body can and should be working at a sustainable rate. Unfortunately, these are often very expensive to undergo, there are DIY threshold tests you can do, if you would like to know yours and track your runs including Heart Rate let us know and we can work yours out for you. This figure which can be down on heart rate or running pace is the key to how fast you should be setting off and how much you should be speeding up throughout the race. Usually the longer the race the smaller the increase in speed.

If you have seen a plateau in running times or have been struggling to make PBs recently give this process a go. Try it in training before trying it in a race or PB effort, be patient, focus on heart rate zones and pace. If you have any questions around running negative splits or would like to know more leave us a comment or get in touch.






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