In the first article of this dossier, we discussed with some figures the relationship that exists between Carbohydrates and Exercise. Today, we will look at how this relationship impacts the moments preceding the competition: starting from the last minutes before the race and going back to the last days.
THE LAST 60 MINUTES BEFORE THE START.
Drinking and eating sweet 30min to 60min before the start of the race is something you certainly do. It is a widespread practice because it occupies, it reassures, it allows to “fill the reserves”… But did you know that it could also lead to a state of hypoglycemia? Yes, due to a rebound effect after the hyperglycemic state, a drop in blood sugar levels is often observed just before the event (30′ to 15′ after the start). It bodes ill for the future, doesn’t it? Especially when you can’t feed while swimming…
But be reassured, if this hypoglycemia phenomenon is real, it does not always translate into a drop of performance. Rarely even, since studies on the subject show that, on average, performance is unchanged despite this practice. The problem actually arises for people who are “naturally sensitive” to hypoglycemia: these people have an interest in adjusting their carbohydrate intake before the competition by choosing foods with a low glycemic index (to limit fluctuations in their blood sugar) and by delaying carbohydrate intake as close as possible to the start (5′-10′ before the event). For others, no problem, your routines can be maintained.
THE LAST TWO DAYS BEFORE THE COMPETITION.
Since the end of the 1960s, nutritional recommendations have been consensus around a high intake of carbohydrates in the last 24-36 hours (10g per kilo per day). This, to “inflate” the body’s glycogen stores, which can then rise from ~500g to ~700g. More recently, studies performing intramuscular measurements have specified this time window: an interval of 48 hours before the test seems optimal to inflate stocks as it also corresponds to a tapering time.
Indeed, as glycogen stocks are no longer as degraded as usual in the tapering phase, they inflate if a significant intake of carbohydrates is made. The dose of 10g.kg.j is therefore all the less relevant in the pre-competitive phase as tapering is driven by the athlete. Consequently, 5-7g.kg.j of carbohydrates are sufficient to generate overcompensation of glycogen stocks. On this basis, a good guideline that we advise you to maintain in your plates at least half carbohydrate and the rest of fat and protein intake.
The dose of 10g.kg.j is a very important dose, as we have said, even too important for the athlete. So be careful if you try to approach it, because this dose may cause you to deviate from feelings of hunger or the level of food tolerance. It is this tolerance that must remain your priority. Indeed, your brain knows your food tolerance better than anyone else… Instead of betting on a predefined amount of carbohydrates, our advice will be to bet on their variety in your plate: fruits, starchy foods, vegetables,… will facilitate the intake of carbohydrates at the same time as their use.
Finally, note that even if this carbohydrate “overload” is recommended by many, it does not guarantee 100% improvement in your performance. Sometimes the athlete does not see a big difference and this happens all the more often as he has eating habits already rich in carbohydrates.
CARBOHYDRATES AND TRAINING.
One of the most remarkable metabolic adaptations with endurance training is the reduction in the use of carbohydrates in favour of fat for the same exercise intensity. This adaptation is fairly well known and has led to interpretations such as adopting a high-fat diet to improve performance (see Part #3). However, it should be remembered that while endurance training does increase fat consumption at an absolute intensity (eg. 12km.h), this increase is invisible at a relative intensity of exercise (eg. 65% VO2max). Clearly, training makes the athlete more effective at a given pace but not at a given physiological effort. And this applies to both fats and carbohydrates.
In this context, different nutritional strategies have emerged. All are based on the fact that Training and Nutrition activate certain metabolic pathways that are identical. Example: Both can induce greater lipid oxidation or promote mitochondrial production. This convergence between Training and Nutrition is therefore a real opportunity for the athlete to accentuate the adaptations respective to each stimulus.
However, adopting a nutritional strategy during training places the athlete in front of a paradox:
– Does he need to increase his energy availability to be able to sustain exercise intensity? The risk then being dependence on these energy sources.
– Or should he limit this availability in order to teach his body to function more efficiently? Risk is the difficulty of holding intense sessions.
Different options are open to you, each of them proposing its foundations. We’ll talk about the “Train-Low”, “Sleep-Low” and “High-Fat Low-Carb” regimens.