Guest Post: Race Prep tip #10: Don’t go out too hard

Today’s guest blogger is Les Corson – a marathoner and ultramarathoner, with a love for trail running and his running mates.  He posts occasionally at

So, you’re about to to run your first marathon, and armed with all this advice about how to run it. One piece really stands out, “Don’t go out too hard!”. Easy really. I mean, simple, straight to the point, it’s not ambiguous. Or is it? What does that really mean, and how do I apply it to me?

Quite simply put, there is a pace (and ultimately effort) that you will be able to sustain for the marathon that will enable you to hit your target time. You do have a target time? You don’t? Then how do you know how fast you want to go? (And this can often can be remarkably different to how fast you CAN go!) This post is aimed at those who have a target time; but those that don’t, read on – pacing applies to all of us.

The faster you want to run, the more likely you are going to experience “The Wall”, that moment when energy stores fail, and lactic acid builds up to the point that the body cannot expel it efficiently enough. How do you know the pace you need to avoid this? There are many ways, doing V02 tests, lactic threshold tests on treadmills are one way. But the simplest way is to incorporate race simulation into your training. In other words, find that point of crossover in training before you find it in racing.

These run types are as follows;

  • Tempo runs (i.e. short warm-up, medium distance run (say up to 10k) run at somewhere between 60 and 70% effort, where 100% is completely flat out),
  • Increasing pace. At the end of a long Sunday run, use the last 5k’s to increase your pace to your expected marathon pace. This gives a twofold benefit. Firstly it allows you to run the majority of your run easy (saves the legs), then you get to experience the increased effort required for late in the race. And no matter your skill/speed/experience, late race fatigue will be experienced by most, if not all of us. Running at marathon pace also gives you an insight into what that pace actually feels like.
  • Consistent mileage. Seems strange this one, but the more consistent runs you do, the more you will fatigue, but you will also toughen up those legs. The better chance you have of holding that pace just that little bit longer. (assuming you rest and taper effectively)

And getting back to that expected marathon pace, how do I know what it is? Well, there are many online pace calculators that will help. If you’ve run a race (and I mean really raced it, not just turned up and trotted through) you can plug that time and distance into a calculator and get an expected race distance time. Be warned, the bigger the gap between race run, and target race distance, the greater the degree of inaccuracy. For a marathon, a half marathon time is ideal, 15k not too bad, 10k at the very least. You can use a 5k time, but my experience is that they just don’t stack up. One such calculator is Run Coach. They have a Basic and Advanced calculators.

On race day, follow these simple rules;
The first 15k should feel deliriously easy. And I mean deliriously… You should be able to get to the 15k feeling like you’ve done next to nothing. The 2nd 15k should feel much harder, but still being at a comfortable effort. The last 12 will be hard. That is a simplified breakdown, many factors on the day will affect performance.

Be careful using pacers provided at the event. They are not foolproof, so make your own Plan B in case it all goes pear-shaped with them.

Be prepared to slow down early in the race even more if heat and or humidity are a factor. Windy conditions will also affect your performance.

Above all, keep things simple for your first marathon. Too much information, particularly too much tinkering with your programm will leave you with inconclusive results (dunno what worked, and what didn’t).

Enjoy it and it will be worth it – whatever happens on the day.



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