How to pace for a PB

Preparing for a big race? Set yourself up for a strong performance and nail that PB with expert running coach Tom Craggs' expert tips.

How to pace for a PB

Marathon season is on its way. Months of hard work, long runs, interval sessions and miles come down to one day. It’s incredible how often runners throw this hard work away by going into a race without a plan or by deciding on the day to throw their plan out of the window. 

In the years I have been coaching I have watched athletes of all standards race half and full marathons around the world and I have paced athletes from beginners to elites in major marathons and I can honestly say that I think MOST runners are not great at pacing their key races. This article covers some of our top pacing tips and things to consider when deciding on your strategy!

Race preparation

Before you even get to marathon race day, your placing plan requires you to think and plan.

  • Target driven or training derived? How are you going to determine your target? Have you plucked it from the air because you WANT a sub 3 or sub 4 marathon? Or is your target derived from the training you have actually done? Your pacing target needs to be realistic!
  • Where’s the evidence? Ultimately you need to have included sessions in your training that will show you that pacing plan is realistic. Include planned blocks of race pace running at the end of your long runs. For example for a half 1 hour 45 minutes to include 3 x 15 minutes at half marathon pace in the final hour. For a marathon get used to progressing the pace of your long runs. For the experienced runner 35K run as 10K easy, 10K at marathon pace, 5K easy, 5K faster than marathon pace, 2K hard, 3K easy is a real test, can you progress?
  • Seek confirmation: Head over to our events hub and consider including a 10K in your half marathon training or a half marathon in your full marathon training and run it at your goal race pace. How did it feel? Are you being realistic? What was your heart rate and is that something you feel you can sustain for twice the distance? For a marathon there are various methods you can use to help you work out a goal pace. If you race a half marathon hard in your training one approach is to double this and add 15-25 seconds per mile to your pace (closer to the 25 second end if you’re a little slower), some like to double their half marathon time and add 10-15 minutes to get a broad idea. If you have only raced a 10km hard then try multiplying this by 5 and subtracting 10 minutes to give a broad idea of a marathon target.

Race day

So you have worked out you pace and practiced it in training. Here are some further considerations and strategies to get it right!

  • Course factoring: Consider the nature of the course in your plan. Is the first half flatter and second half hilly? If so you might need to consider running the first half quicker. Will you likely be penned in and slowed by crowds in the first 5km? I will always look at the environment in which the athletes I coach train in and run their key marathon paced sessions and work out a factor to adjust it to differences they will face on the day. This might include heat, hills, altitude and road/trail surface.
  • Weather conditions: It’s hard for runners to be realistic and adapt. I have seen so many runners have very tough key races because they refused to adapt their target around conditions. If you have been training at your goal race pace in 10-12 degrees and you hit race day at 23-25 degrees the likelihood is your best pace ON THAT DAY is going to be slower. Don’t be pig headed, accept and adapt and adjust your pacing plan for the heat or a strong head wind - you’ll need to be particularly conservative at the start.
  • Go old school and write it down: GPS watches are great but in a big city half or marathon don’t rely on your GPS to help you pace. The number of other devices around you as well as buildings etc can interfere with your signal. You’ll also be unlikely to run exactly the right distance however much you try to stick to the fastest line the chances are with some wide turns, over taking, water stops you’ll run a bit further than the distance. The sure fire way to pace on the day is to write your splits on your wrist or use a pace band and then use a simple stopwatch function to check your leg against the race mile or km markers.
  • Stick on plan: This of course is the classic. You have trained for a 2 hour half or a 3:30 marathon, you have set your plan, you have it clear in your mind. The gun goes and suddenly your Paula Radcliffe or Dennis Kimetto, the plan is out of the window because it all feels SO EASY. Of course it does! It’s race day, you have tapered, the adrenaline is high and, particularly for a marathon, most will not have run the full distance in training. The truth is however you approach your pacing plan the first few miles will almost always feel easier - hold it back and don’t sabotage yourself.  

The options

  • Positive split: This is what we see most often - runners running the first half of the race faster than the second. More often than not though this comes from poor pace judgement rather than a specific plan. Aiming to ‘bank’ time early on is a poor approach. You will use up your vital glycogen stores too early in the race and risk the wheels coming off in the final 5K of a half or 10K of the marathon. It can sometimes, rarely work. Steve Jones broke the marathon work record with a big positive split, but for most non elites running the first have significantly too quickly to bank time will lead to pain later on!
  • Even split: Just as it sounds even splits involve running the first and second half of the race at the same pace, or close to the same pace. This is likely to be a very effective strategy for most runners. Be aware though that as your body tires through a marathon your oxygen consumption will start to rise a little and your HR drift up. As such ‘even splits’ might actually require you to 2-3% faster in the first half than the second, so in fact a very subtle and planned ‘positive split’. In a half there is no reason to do this if you are well trained.
  • Negative split: Most of the world records at the marathon and even half marathon have been set with runners completing the second half of the marathon faster than the first. I believe this pacing IS achievable for non-elites as well but it takes a lot of confidence and discipline and practice in training. Starting the first 5km of a half or 10km of a marathon a few seconds per mile slower than your goal race pace, running the middle 10-20K bang on your goal pace and then forgetting the watch and throwing everything you have got at the final miles. Look in front pick a vest, pull it in and over take before focusing on the next, racing your way to the finish line!
  • On feel and adapting: If you are running just to complete the marathon or don’t have a really clear goal pace you want to run you can take a less planned approach. Forgetting the watch and just listening to your breathing and your body. In a marathon aim to remain fully conversational in the first 10-15km of the race, the middle miles should feel steady but controlled before pushing on to 4-5 word answer effort for the final miles. Sometimes you might want to adapt within the race if you have a good group running well at your pace. My best advice though is to keep the first half of the race to a set plan before you start to make these kinds of alterations.

For more advice, read everything you need to run your first marathon

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