Why ‘Hitting the Marathon Wall’ Happens and How to Avoid It

South Africans are marathon crazy. Nowhere else in the World has as many 42.2km distance races on their running calendars. In most countries runners will take part regularly, in races varying from 10km to the half marathon (21.1km) building up gradually to the full distance, attempting that, at most, once a year. Not South Africans. Here it is not at all unusual for runners to race the distance that Pheidippides covered between Marathon and Athens at least once a month as they first qualify and then train for even longer, Ultra-distance races, the Two Oceans and Comrades Marathons. Perhaps that is why the marathon distance seems to not be as big a deal to the average South African runner. The fact that most recreational runners aspire to cover race distances of 56-90km may make the standard marathon seem less daunting.

Perception notwithstanding, running a marathon is a significant achievement and a challenge that should not be taken lightly. There are a number of legends and tall stories that abound in marathon running but one that is definitely more fact than fiction is known as ‘hitting the wall’. Every marathoner has a story about their race falling apart after two hours.

What does it feel like?

Hitting the wall is both a physical and mental struggle which seems to occur quite suddenly. We go from cruising along at our goal pace, having everything under control, to struggling to put one foot in front of the other. Our legs develop a deep ache and our inner voice becomes extremely negative, questioning why we are doing this, second guessing our preparation and trying to convince ourselves to quit. The drama is quite funny in hindsight and is the source of many hilarious anecdotes from the more verbose in the running community but, at the time, it can feel like our running world is collapsing around us.

Why does this happen?

The wall is hit when our bodies deplete their glycogen stores. Our body and brain don’t know that we are out there having fun. They treat everything as life and death and start conserving and prioritising energy use in order to stay alive. They are not concerned about our marathon PB or kudus on Strava and they do everything in their power to make us slow down and, if at all possible, stop running altogether. Working in unison with the physical and mental assault, they can be pretty convincing.

The reason we need to slow down is that the body now needs to start utilising more fats in the fuel mix but fat is a more complicated source of fuel to access and can only be done sufficiently, at lower exercise intensities. Even the leanest of runners has almost unlimited stores of fat for fuel but glycogen, stored in the muscles and liver, only lasts approximately two hours at high exertion levels. That is why the ‘man with the hammer’ normally arrives at around the two hour mark of a marathon.

Is our appointment with this guy with his leg smashing implement inevitable and, if not, how do we prevent it from happening? Yes, of course we can prevent this situation, which is also known as ‘bonking’. The keys are: proper preparation, adequate fuelling and correct pacing.

Preparation – The Long Run

These should be done every week and make up about a third of your weekly mileage. More experienced runners will aim for a secondary, midweek long run as well. Most of our long runs should be done at a low intensity. Training at lower heart rates allows the body to utilise more fats as fuel. The more we do this, the more efficient the body becomes at metabolising fats for fuel and we can use more fats in our fuel mix at higher intensities. This will then conserve our glycogen stores so that they last longer into the race. In the final phase of our marathon preparation, we can start introducing more and more time at our goal marathon pace and intensity into our long runs in order to become more efficient, both mentally and physically, whilst running at these levels on fatigued legs.

Fuelling

We should be aiming at consuming a gel of 30-40g of carbohydrates every half an hour in our marathon and that is right from the first half an hour. Giving our bodies glycogen to use during the race will allow it to conserve the stored glycogen, allowing us to stretch our glycogen stores well beyond the two hour limit. We should also practice this in training, during our long runs, even when these are run off at lower intensities. We do this in order to train our gut to break down this fuel with less blood than is normally available. Remembering that blood is being diverted to the working muscles.

Pacing

Our race day pace needs to correspond with what we have achieved in training. The time for ambition occurs when we first start planning that training, not after the training has been completed. If we aspire to lofty targets in the marathon we need to plan our workouts accordingly and, if our sessions have fallen short of our ambitious aspirations, we need to adjust the race day strategy to match our reality. Going out too hard, too early will burn through our available energy stores and leave us losing an argument with the Man with the Hammer later on.