Carb loading before the marathon

Carb loading before the marathon, to a greater or lesser degree, is something that all competitors should consider.

On the day, the priority is to maximise your energy stores in order to maintain a reasonable pace for the whole distance, and this means ensuring that you have as much glycogen as possible stored in your muscles and liver.  Carb loading, which simply involves eating a higher proportion of carbohydrates in the last 2-3 days before the race, can go some way to helping you to achieve this, providing you have done the training beforehand.

Some experts suggest that carb loading can be even more effective if you go through a depletion phase. This begins with a long run a week before the race, which depletes the glycogen in your muscles.  Muscle glycogen levels are kept low by following a low carbohydrate diet for about three days after this, before the final carb loading in the last 2-3 days.   This can be a risky strategy, however, and others suggest that depletion runs (typically a long run, first thing in the morning, without breakfast) are more useful in terms of training the body to burn fat more effectively, and these are best completed in the early phase of training.  The reasons for this are:

  1. Your long runs in the early phase are short enough to be able to complete in the fasted state (perhaps 10-15 miles).
  2. You need to practice your race day nutrition routine during the longer long runs (perhaps 15-20 miles) that you carry out closer to race day.

When I trained for my one and only half marathon, most of my long runs in the last 6 to 8 weeks before the race were completed in the fasted state over approximately the half marathon distance.  This, along with other work such as hill training, intervals and tempo runs, and a sensible recovery schedule, resulted in a very pleasing performance of 1 hour 32 minutes and 21 seconds. This time may seem impressive to some and unimpressive to others, but I definitely achieved close to my peak performance (it compares very favourably with my 10K and 10 Mile best times), so my preparation was effective.

I actually plan to run this same event again in February, prior to my debut marathon in April, and intend to follow a similar training routine, with the aim of getting another good half marathon time.  This then gives me about 9 weeks to build up the mileage on the long run and establish a nutrition strategy for the 26.2 mile event, hopefully in the knowledge that I have well developed fat burning mechanisms to help me keep going reasonably strongly for a ‘double half marathon’.

Trying out your carb loading schedule, including the foods you actually consume, prior to at least a couple of the long training runs, is strongly advised.  For example, many experts suggest sticking to more processed carbohydrates to minimise any possible negative effects of fibre on the guts.  However, others will argue that you should stick with what you are used to, so if you normally eat wholemeal bread, for example, then you should continue to do so during carb loading.  So the only sure way is to experiment and see what works for you.  For example, I like porridge oats and value its healthy and nutritious properties, but have found that it feels heavy on my stomach if eaten as my pre-race breakfast.  Perhaps I will try flapjacks as an alternative, probably in addition to bananas and possibly toast and marmalade.

It is also strongly recommended that, as well as water, you take on carbohydrates during the race.  These may be in the form of energy gels or drinks, or sweets such as jelly babies.  You might even want to eat a ripe banana immediately prior to the race. Again, the key is to experiment on your long training runs and see what works best for you.

I have just bought a pack of isotonic energy gels of different flavours, and I took one of these (and water) after about 9 miles of my 13 mile training run today, to see how easily I can take them while running.  My hands were cold so I found it hard to open the sachet but I just about managed it. It was a bit like sucking on a sachet of hotel shower gel, and the taste wasn’t much better, but if it does the trick that’s not important to me.  Medicine doesn’t have to taste nice (though I used to love the cough syrup I was given as  child).  I can’t say I noticed any effect, positive or negative, on my energy levels during the last thirty minutes of my run, compared to when I just carried on without food (or water), though I would probably need to go further to notice any benefit.

My isotonic gels contain 30ml of gel with 22g of carbohydrate in each, so if I choose this option I will be looking to take one every half and hour during the marathon.   Since these isotonic gels are quite heavy, especially if I am going to be carrying six of them, I am now going to order and try some non-isotonic energy gels.  These will be lighter since they aren’t trying to provide water, which you can get at the drinks stations.  The possible disadvantage is that they may be a bit sticky and harder to take when running, so watch this space and check out my post Training update – energy gels promising? 

2 Replies to “Carb loading before the marathon”

  1. Great article. I’ve heard of people completing 24 hour marathons and refuelling on 1-2 jelly baby sweets every hour or so. I think I’d love carbs too much to be able to restrain myself that much!

    1. Hi Sharon. Thanks for your positive comments. I’m glad you mentioned the jelly babies. I was going to try this method of refuelling, but since the gels seemed to work ok, I sort of forgot about them. You have inspired me to still try them out to see if they work even better, or if I choke as I try to eat and run at the same time. I don’t think I will overdose as I can take or leave these sweets. Sherbet lemons would be another matter (though even more of a choke hazard).

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