🍯 WHY would you need to supplement carbs during longer endurance events?
↗️ With increasing intensity, let us say you go from walking to fast running, the body will rely (in relative and absolute terms) more on carbohydrates (glucose) as a fuel compared to fats (free fatty acids). This is because per molecule oxygen, the aerobic oxidation (burning) of glucose yields 7% more ATP (energy) than the oxidation of fats. The harder you exercise, the more limited oxygen becomes, so metabolism switches to the most efficient energy source per given amount of oxygen.
💨 Glucose is the super fuel during exercise.
❗️ Importantly, you cannot run on this super fuel forever. The stored amount of carbs in the body (liver and muscle, called glycogen) is limited to 1000-3000kcals. Thus, without any supplementation, you would run out of glucose in 1-2h during (intense) exercise. That is why many people meet ‘the man with the hammer’ 30km into a marathon, because they forgot to eat and glycogen becomes depleted. There is nothing that can be done, except decreasing the intensity to rely on fats as fuel.
🥑 Fats are stored inside the muscle (good for approx. 2000-3000kcals) and over the rest of the body (under the skin, between the organs,… good for 50 000-100 000kcal of energy). Technically enough fuel for 15-30 marathons, even for the leanest athletes.
👉Thus, for most events that require intensity (running a marathon fast, Olympic distance triathlons, cycling races,…) the athlete should supplement carbs to optimize carbohydrate metabolism to provide energy to the muscle in the most efficient way. On the other hand, during very very long events, like ultra-marathons, ultra-cycling races etc… some athletes experiment with low-carbohydrate diets to optimize fat oxidation. Because these races are so long, the intensity is lower and the predominant energy source is fat oxidation. Refraining from carbs ramps up fat metabolism and that might be an advantage during events that last 24h+ because fat provides near unlimited energy. 🧐
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#carbohydrates #enduranceevents #marathon #triathlon #cycling #exercise #nutrition #glycogen #ATP #fatmetabolism #ultrarunning #ultracycling #lowca
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