The Simple (Simon) Guide to Racing a Marathon – Part one: Timing

It was my birthday a while ago and my aunt sent me one of those gently amusing cards that cause very little offence or mirth. Here it is…

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But it got me thinking about how all too often, achieving a goal can become a daunting exercise over over-whelming complexity. I know it was for my first few races.

But now I take a much simpler approach to the marathon and I thought I would share my plan with you in four blog posts over the next week:

  1. Timing (this post)
  2. Hydration
  3. Nutrition
  4. Psychology

Time to think about time

I really strongly suggest that you do not use a GPS to manage your pace on race day. They are notoriously inaccurate and especially when surrounded by 37,000 other GPS watches.

If you are running a marathon that has its course measured by the Association of UK Course Measurers, then the mile markers are accurate. Very accurate.

If your GPS beeps to tell you that you have run a mile before or after the mile marker… then your GPS is wrong. Thinking otherwise is a mistake that too many runners make.

If you accept that your GPS device might be a bit out, then think about this: if your GPS is short by 15 seconds per mile, that is six and a half minutes for a marathon. If you are aiming for a sub-4 hour marathon, your GPS only needs to be 43 meters out per mile – which is only 2.7% – and you will finish in 4 hours 6 minutes.

So what do I suggest?

A stopwatch. I use a GPS watch, but I turn off the GPS function and just use the watch as a stopwatch. Each time I pass a mile marker, I hit the lap button. If the time for the last mile is more than my target pace, I am behind schedule and if it is less than my target pace, I am ahead of schedule. I can then adjust as necessary. Simple.

The next post will be up in a couple of days. In the mean time, what do you use to make sure you are on pace? Or do you not bother with that? Let me know what your tactics are and how you have honed them in the past.


  1. I hesitate to answer this as an old-school runner, who has never owned a GPS in her life, but surely after doing so much training (hopefully), people should have a pretty good idea of the pace they are running. I would agree that a watch is all you need to keep an eye on proceedings and as well as that, you can run always run with a bus load of other peeps aiming for around the same time. I can’t recall… do they also have a clock at each km/mile mark? Anyway, yes… Keep.It.Simple…always. 🙂

  2. “If the time for the last mile is more than my target pace, I am behind schedule.” Not true if you are already 5 minutes ahead before the last mile.

    I turn off auto lap, have ‘average lap pace’ displayed and press lap at each mile marker. If the average lap pace is too high then speed up. Works regardless of satellite signal and if you miss a button press just press lap twice at the next mile. Just don’t press stop by mistake!

    Also the mile markers are often in the wrong place, regardless of whether course has been measured as organisers tend to use nearest lamppost. Not a problem at VLM though with giant inflatable arches.

  3. Another interesting post, Simon.

    I’m not sure I agree that GPS watches are as inaccurate as you suggest. In most test reviews I have read modern devices are generally about 99% accurate against a measured road course and the inaccuracy comes from not following the racing line.

    Of course all technology can malfunction.

  4. When I ran my marathon PB at Barcelona I hooked on to the race organised pacers. They were bang on the money time wise, and with 6 miles to go I had enough in the tank to push on in the last 10k to come in a few minutes quicker than my target time. On the plus side, I was able to mentally switch off from thinking about time as the pacer was wired up to the millisecond (at half way was only 2 seconds quicker than target pace!). On the minus side, I’ve heard others who have used pacers in other races miss their target time cos the pacers weren’t running on time. In sum: Can be useful as a guide, and as you’ve put in other posts, the benefit of running with a pack can help you overcome feelings of fatigue if you’ve trained properly and can maintain target marathon pace.

  5. Will, I like your idea on recording and showing average lap pace. I display an overall average pace on my garmin and tend to focus on that during races, seems to work quite well but may look at combining it with the average lap thing when I give marathon distance a go next month…. although I’ll probably scrawl target mileage splits on my arm as well, belt and braces and all that 🙂

  6. I noticed this when running in a half marathon a month back. I find myself a looking at my gps a little too much when out on the road. I actually find it decreases my time sometimes (By setting out too fast). Great post!!

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