Glycogen is the body’s form of stored carbohydrates. It’s what the body is able to tap into and use for energy throughout the day and especially during workouts. There is a connection as well between one’s glycogen level and the body’s hydration. While there is still a lot to learn regarding this, there’s plenty to keep in mind. Especially if periodizing your nutrition between stretches of high and low carbohydrate intake.
High glycogen level effects
Having increased glycogen in the body is very beneficial in moments of increased activity. It’s similar to stating a long cross-country car ride with a topped off gas tank. As exercise goes on, the glycogen will continue to be used until it gets too low at which point the body will start to pump the brakes. While in the middle of a practice or a game you don’t want to be hitting the brakes so ensuring that extra glycogen is on hand can be very helpful.
Increasing glycogen levels is done primarily though the popular strategy most refer to as “carbo-loading”. This is done where ~48 hours before the event, carbohydrate intake is increased. Eating more carbs pushes the body to store a lot of that as glycogen, thus topping off the tank. The level of carbo-loading can vary depending on the event but the most popular ones include long endurance events. Ultra-marathon runners and long-distance cyclists such as during the Tour de France really utilize this. For shorter duration activities such as for sprinters, this strategy likely isn’t necessary. In fact, it could potentially be slightly detrimental due to the water effects we’ll discuss later.
Low glycogen level effects
While high glycogen levels have gotten a lot of attention in the past, we’re continuing to learn a lot of benefits that can be gained from low glycogen levels. Low glycogen benefits are gained from their impact on training adaptations. It’s not something to purposefully be done going into competition.
Training with low glycogen can force the body to have to pull from its fat stores more. To keep the body going during the training session if glycogen isn’t available it has to keep getting energy from somewhere! Adding in some low glycogen sessions and increasing the body’s ability to pull from fat could in theory help to preserve glycogen stores in future events. With fat and glycogen being the two main sources of energy, having that flexibility is very beneficial. Low glycogen sends the signal to hit the brakes so if preserving that, longer training sessions can occur.
Decreasing glycogen to create this state in the body can happen through two methods typically. One is by eating a low carb diet at strategic time points. As mentioned previously, glycogen is a stored version of carbs in the body. So, if not consuming carbs in the short term the body will still be pulling from the glycogen for a bit and the amount decreases. Another strategy is having two training sessions in a day. The first session is higher intensity to really drain the glycogen, then a second session after it is done while glycogen is still low. A workaround for this is sometimes doing a fasted training in the morning after an overnight fast while sleeping.
Glycogen and hydration connection
We know what glycogen can do performance and energy wise, now we can dive into how it can impact hydration. Specifically, the impact that it has on the body’s retention of fluid. On average, for each gram of glycogen, the body also holds 3-4 grams of water. As a result, carbo-loading can result in extra fluid being held on by the body. On the opposite end of the spectrum, low glycogen levels could result in less water being held onto.
Due to the water retention component, glycogen levels can also impact your weight acutely. After a carbo-loading phase it can cause a noticeable increase in weight. While the benefit of the extra energy is great, it needs to be taken inconsideration of the negatives of being heavier. This is why it can be more negative for sprinters. Sprinters don’t need that extra energy on hand for short duration. If having that extra weight as well it could actually make it tougher to accelerate and hit/maintain top speed.
How much glycogen is needed?
Consideration needs to be taken for what type of event are you fueling for. That is where it all starts. Shorter events generally less than 2 hours long may not benefit from a traditional carbo-loading approach. Longer events on the other hand will likely benefit from all the extra energy possible. Regardless the event it’s important to make sure you are eating enough in general. But the amount of carbs can be adjusted for glycogen needs/goals. Consuming carbs 24/7 isn’t always the answer so make sure you are giving your body what it specifically needs for your goals.
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