The days leading up to a run are often a source of questions about diet. The training load gradually decreases in order to optimize recovery—to the extent that the energy expenditure is no longer the same on a daily basis. However, it is important to have optimal energy reserves on the day of the run. How do you navigate this, and how do you know if certain strategies, such as glycogen loading, are useful for you? Here are some guidelines!


The eating habits

First of all,  the eating habits that you adopt in the days leading up to your competition will largely depend on the type of event that you are about to take part in. In any case, you will have to pay particular attention to your intake of carbohydrates, as they represent your main source of fuel during the exercise. However, your needs will vary according to the length of your event. Indeed, your muscles normally have glycogen stores capable of sustaining energy output lasting 90 minutes or less. So a normal diet with a carbohydrate intake adapted to your training level will therefore ensure that this source of fuel is available. However, after 90 minutes of exertion, the body becomes exhausted if no external energy supply is provided. Many athletes have hit this notorious wall during long events. The body no longer has access to a sufficient amount of energy and is therefore unable to maintain the intensity required for the exertion. However, it is possible to optimize our energy reserves by maximizing the quantity of glycogen that our bodies store in the days before a competition. So this gives us a little head start. This strategy is better known as glycogen loading.

For events that last an average of 90 minutes or less, i.e. try-a-tri or sprint triathlons, as well as runs of half-marathon length or less, there is no point in using the glycogen loading strategy.


Before the race

In the days leading up to your event, just stick to your usual eating habits. If you are a little less hungry because your training is less intensive, it is totally appropriate to reduce your energy intake. Particular attention should be paid to your diet the day before your event. At this time, it is important to make sure that your body has adequate carbohydrate availability for the day of your event. So be sure to increase your carbohydrate intake the day before the run by choosing foods that are low in fibre and fat, to avoid overloading your digestive system. There is no point in having the substantial portions you would have when glycogen loading. Simply try filling half your plate with a portion of starchy food at mealtimes and add fruit or a carb to your snacks.


For events that last longer than 90 minutes, extra special attention should be paid to your diet during the two or three days before your run. In fact, athletes preparing for long-distance triathlons, such as a 70.3 or an Ironman, will certainly benefit from the glycogen loading strategy. Athletes who are preparing to take part in an Olympic triathlon or a marathon are also likely to benefit from this strategy. To do so, you should plan to increase your carbohydrate intake substantially in the two or three days before the run. We’re talking about a carb intake of up between 10 to 12 grams of carbohydrate per kilogram of body weight per day. That’s a lot of carbs to eat! To avoid digestive discomfort, opt for grains, but not whole grains, and add sources of concentrated sugar every day, such as maple syrup, fruit juice, candy, sports drinks, chocolate milk or dried fruit. Also note that glycogen loading should be accompanied by optimal amounts of water. Indeed, every gram of glycogen is stored in your muscles along with two to three grams of water. Therefore, to ensure good carb loading, you should drink a little more and not worry if the numbers on the scale go up slightly.

Many athletes find it hard to visualize what an intake of 10 to 12 grams of carbohydrates per kilogram looks like—to the extent that their carb intake is sometimes not enough to achieve good glycogen loading. If in doubt, don’t hesitate to consult a nutritionist who specializes in sports nutrition to have a plan tailored to your needs.