Watch out for the wall!

Mass endurance events like marathons are a great opportunity for recreational athletes to compete on the same stage as elite athletes. Everyone taking part shares the prospect of hitting the wall at some stage in the race. From a physiological perspective, hitting the wall occurs because your body’s stores of carbohydrate are unable to provide the energy required to maintain the current pace. This is due to muscle glycogen depletion and low levels of blood glucose. Hitting the wall is characterised by a drastic reduction in running pace of around 30 seconds per mile for elite athletes and 1-2 minutes for recreational athletes. It may mean that some people end up walking because they simply do not have the energy to go any faster.

The main strategies available to athletes of all levels are to take on carbohydrate/fluids so energy delivery can keep up with energy demand and to ensure that energy stores are topped up prior to exercise (carbo-loading).


Taking carbohydrates during the marathon will help delay fatigue as the glucose from these products enters the bloodstream and helps maintain the rate of carbohydrate oxidation. It may also help prevent the increase of serotonin in the brain which has been linked to feelings of fatigue and de-motivation. However, even if you’ve done a good job of carbo-loading you’ll still only have ~2,000 calories worth of glycogen stored in your muscles and liver and will still have to take on more fuel during an event like a marathon. It’s a bit like the fuel tank in your car – you can fill up before you start your journey but the tank is a certain size and can only take a finite amount of fuel.

If you start to feel the effects of hitting the wall during an endurance event like a marathon then it’s probably a bit too late, particularly for higher level athletes. Recreational athletes may have another hour or so of running ahead of them and so the important thing is to take on carbohydrates in an easily digestible form. It’s therefore important to keep an eye on your race pace because setting off too quickly will accelerate the depletion of muscle glycogen. Ensure you stick to your plan and run your own race. 

At this time of year, its also important to be aware that your body tends to utilise muscle glycogen at a higher rate when exercising in the heat. Lactate accumulation also tends to be higher in warmer weather and when combined with reduced muscle glycogen could result in fatigue meaning you “hit the wall” earlier than anticipated. Temperatures can rise quite quickly during the day even if it may be chilly first thing in the morning. If temperatures are likely to be relatively warm on the day of your event, it may be a good idea to reduce your initial pace in order to help conserve your fuel stores for later on.

As an exercise physiologist, I can help mitigate the effects of hitting the wall by developing an understanding of your physiological make-up and how you perform during training or endurance event like a marathon. I can also calculate your ideal pace to help maximise performance and understand how your body will react when performing at that pace over a prolonged period of time – it’s rather like the engineers of a formula 1 team calculating the optimum amount of fuel required and looking at other variables in order to help maximise performance!!

Finally, concentration and focus may also help you cope with “hitting the wall”. Try and avoid dissociating yourself from the race by thinking about that “beer waiting for you at the finish line” or “planning your summer holiday”! During the toughest moments in a marathon, Paula Radcliffe reportedly counted from 1 to 100 to help her ward off negative thoughts and to keep her in the moment!