Have you ever wondered what gives you energy during a workout or sports competition? The secret lies not only in the heartbeat or muscle contraction, but also in a lesser known element: glycogen. This molecule is the main storage form of glucose in our body, acting as an essential energy reserve during physical activities. For athletes, managing glycogen levels can make the difference between reaching your limits and exceeding them.
Glycogen's role in athletic performance is multifaceted, influencing everything from sprint power to endurance capacity. Its importance cannot be underestimated, particularly in sports requiring rapid bursts of energy or sustained effort over time. By diving deep into how glycogen works and exploring how it can be optimized through diet and training, athletes can significantly improve their performance and recovery.
In this article, we will discover the importance of glycogen for athletes.
Understand how our muscles work ?
Since the idea is not to take an anatomy or biomechanics course, do we limit ourselves to what our muscles need to function effectively? Muscle contraction requires energy, mainly in the form of ATP (adenosine triphosphate). Muscles obtain ATP through the breakdown of carbohydrates (glycogen), lipids and, to a lesser extent, proteins. We leave it there, it will be enough for the rest.
What is glycogen ?
Glycogen is an essential fuel source for athletes, crucial for high-intensity performance and endurance. Understanding its role can transform your athletic abilities and recovery. It consists of long chains of glucose which, when broken down, provide a quick and efficient source of energy for exercise.
Glycogen, stored in muscles and the liver, is the main source of energy for the human body. It can be quickly mobilized and can produce energy efficiently, but these reserves are limited. In a well-trained athlete, they can provide energy for approximately 90 to 120 minutes of moderate to vigorous intensity exercise. Like a car engine that consumes more electricity or gasoline at high speeds than at medium speeds, glycogen is depleted more quickly if the effort is intense. When there is no more, it's the end of the line, the setback! Note that the glycogen stock is replenished very slowly, from 24 to 48 hours if the stocks are empty.
What are carbohydrates ?
Carbohydrates are therefore a broad category of nutrients found in many foods and are an important source of quick energy for the body.
They are composed of sugar molecules and are classified into three main types:
- Monosaccharides (like glucose and fructose)
- Disaccharides (like sucrose and lactose)
- Polysaccharides (like starch and cellulose).
Carbohydrates are consumed through the diet and are metabolized by the liver and insulin to provide immediate energy or to be stored as glycogen in the liver and muscles.
How to replenish glycogen stores ?
The strategy is to eat early and regularly by providing the body with an external energy source in the form of carbohydrates through solid and liquid food. This has several advantages:
- We preserve muscle and liver glycogen reserves in order to use them later.
- We maintain a stable blood glucose level, which is key to avoiding drops in performance and feelings of fatigue or hypoglycemia. During a short effort, the liver can release glucose to maintain blood sugar levels, but over a longer period of time if you don't eat properly... the race will get complicated.
- This allows better management of the absorption and digestion of nutrients, thus avoiding gastrointestinal discomfort that could occur if you wait until you are in a state of advanced fatigue or physical stress before eating.
- Finally, this makes it possible to optimize recovery in relation to the stock reloading time seen above.
If there is no more glycogen and no external carbohydrate intake, the blood glucose level drops, then it is the turn of insulin to decrease. The body will still produce it to protect itself. Remember that the heart is a muscle and it is better for it to remain active.
- Gluconeogenesis : In response to glycogen depletion, the body increases the production of glucose from other non-carbohydrate sources. This conversion can be done from lactate, glycerols (derived from lipids), and amino acids (from protein degradation). This can lead to a loss of muscle mass if this state is prolonged.
- Ketogenesis : If activity continues or if there is prolonged fasting, the body begins to use fatty acids more significantly for energy. With the increased breakdown of fatty acids, the liver produces ketone bodies, used as an alternative energy source, especially for the brain. This is the famous Ketogenic or Keto diet based on lipids only.
Faced with prolonged use of gluconeogenesis and ketogenesis, the body adapts by gradually reducing its baseline energy requirements and increasing its efficiency in using ketone bodies and fatty acids as primary energy sources. Some athletes, who regularly train to deplete their glycogen stores, can improve their ability to store glycogen and use fat for energy, a phenomenon known as "metabolic flexibility."
Some people think that there is no need to consume carbohydrates because fat is enough. A simple rule of biochemistry says that lipids only burn in the fire of carbohydrates. If there are no carbohydrates, the Krebs cycle does not run and there is therefore no use of lipids by the body. The only way to prove them right is to follow a suitable ketogenic diet.
Carbohydrates for post-exercise recovery
We often hear about the ‘anabolic window’, a period during which the muscles can absorb a greater quantity of protein and thus maintain anabolism, but above all ensure greater muscle growth. Protein should therefore be consumed within 30 minutes of exercise. Recent studies show that protein consumption can be delayed compared with carbohydrate consumption, especially for those who practice sport every day.
Should you eat carbohydrates after exercise? Muscle glycogen reserves are depleted, especially if the effort has been intense or long. These reserves are essential for your future performance, and they take time to replenish (24 to 48 hours). So if they are not properly recharged, the next effort will start with fewer reserves.
After exercise, the body is particularly receptive to carbohydrates, particularly those with a high glycaemic index, which accelerates their storage in the muscles. On the other hand, muscle protein synthesis remains stimulated for several hours after exercise, allowing greater flexibility in their consumption. Research shows that the most important thing is to have a sufficient total intake over the day. Distribute these intakes evenly to stimulate muscle synthesis on a regular basis (at least 0.3 g/kg body weight/meal). Ensure a variety of essential amino acids in protein sources.
What is the glycaemic index ?
The glycaemic index (GI) is a ranking system that measures the impact of carbohydrate-containing foods on blood glucose levels. This index compares the ability of a given quantity of food to raise blood sugar compared to a reference, generally pure glucose or white bread, which have a glycemic index of 100. The glycaemic index, however, does not take into account the quantity of food consumed, it will then be necessary to look further down at the glycaemic load.
Here are the main points to understand about the glycaemic index:
How does glycaemic index work ?
Measure : GI measures the rate at which carbohydrates in a food are converted to glucose and absorbed into the bloodstream. High GI foods are quickly digested and absorbed, causing a rapid and significant rise in blood sugar.
Comparison : A food with a GI of 70 or more is considered high GI, those with a GI between 56 and 69 have a medium GI, and those with a GI of 55 or less have a low GI.
Importance of glycaemic index
- Diabetes control : Understanding and selecting foods based on their glycemic index can help manage diabetes by controlling blood sugar spikes.
- Weight management : Low GI foods can help control appetite and prolong feelings of fullness, which can be beneficial for weight management.
- Cardiovascular health : A diet based on low GI foods can help reduce the risk of cardiovascular disease and other chronic conditions.
Factors affecting glycaemic index
- Preparation and processing : Prolonged cooking, fine grinding, and other processing methods can increase the GI of a food.
- Composition : Foods high in fiber, protein or fat tend to have a lower GI because these nutrients slow down the digestion and absorption of carbohydrates.
- Fruit maturity : More ripe fruits generally have a higher GI than less ripe fruits.
Limitations of glycaemic index
Individual variability : The blood sugar response to a food can vary from person to person depending on many factors, including differences in digestion and metabolism.
Combined foods : The GI of a food does not take into account other foods consumed at the same time, which can modify the overall glycemic response.
The glycaemic index is a useful tool for choosing foods that can help maintain stable blood sugar levels, particularly for people with disorders of blood sugar regulation, such as type 2 diabetes. However, it It's also important to consider other aspects of nutrition, such as overall nutrient balance and calorie density of foods.
What is glycaemic load?
The glycaemic load is essential to prevent excess weight or diabetes. It allows you to measure the impact of a food on blood glucose levels.
The glycaemic load is calculated from the GI of the food and the amount of carbohydrates in a serving. Although the glycaemic load gives more reliable results than the GI, it remains a less practical concept to use on a daily basis, because you need to know the carbohydrate content of each food.
CG = (GI x amount of carbohydrates in food serving (g))/100
A daily glycaemic load (sum of all the CG of foods ingested) is considered low if it is less than 80. On the other hand, it is high if it exceeds 120.
What are the sources of carbohydrates for athletes?
Sports nutrition brands offer many sources of carbohydrates in different forms to regenerate our carbohydrate stores during physical exercise, both in training and racing. You will have to make your choice based on the type of activity, its intensity, the quantity of calories provided and above all the practicality of the product depending on the sport practiced.
Cereal & fruit bars:
Energy bars are essential for athletes, adventurers and all those who lead an active, snacking lifestyle. Designed to nourish and provide a quick boost of energy, these compact, easy-to-carry bars are packed with nutritious ingredients like whole grains, nuts, dried fruits, protein and of course, carbs.
Since they require chewing, they will be used in sports where it will not interfere with breathing and where it is possible to use your hands. Aside from road running and high-level cycling, most other sports are compatible.
Note that the digestion of solid foods takes between 20 and 30 minutes. An energy bar is therefore not an immediate source of energy but rather a slow-release energy product ideal for endurance events such as trail running or hiking.
Energy gels:
Energy gels are essential for athletes and endurance enthusiasts who need a quick recharge of energy during exercise. Concentrated and easy to consume, even while on the move, these gels are formulated to provide a quick dose of simple carbohydrates, often enriched with electrolytes and sometimes vitamins or caffeine for an extra boost. Their viscous texture allows rapid digestion and immediate absorption, thus avoiding the discomfort of cramps or heaviness that solid foods can cause. Perfect for long distance runs, marathons, or cyclists, energy gels offer a practical solution to boost performance without slowing down.
It is advisable to take gels with a fairly fluid texture to facilitate absorption because during exercise, it is easy to have a very dry mouth. This will avoid drinking too much afterwards to wash it down and therefore a risk of bloating.
The choice of packaging is also key. Some are easier to open than others, especially with one hand, cyclists will understand. Others are made of plastic which is not in keeping with the times. Finally, and they are very rare, some are really resealable which has a double advantage.
- Possibility of portioning the gel in several times. This avoids too sudden an intake of sugar into the body which can have the opposite effect than expected, known as reactive hypoglycemia or cotton leg syndrome. To keep your blood sugar level stable, there's nothing better than taking a little gel every ¼ hour.
- A gel that does not close always contains a little product which ends up leaking and sticking. In the absence of a trash can in the wilderness, some unscrupulous athletes will be tempted to dispose of it on site. A resealable gel does not leak so it can be kept until the next trash can.
Mulebar energy gels are both resealable with a cap like a tube of toothpaste but they are also reusable and they are the only ones in the world. Simply rinse them with hot water after use and refill them with their eco-refill. It is ecological and economical. A refill of 12 gels is 33% cheaper than 12 tubes purchased individually.
Gummies:
Gums are fairly new and are supposed to replace gels. These are small gel balls that simply melt in your mouth. In reality they are much less dosed than the gels which requires taking more. Manufacturers announce that they cannot put more than 8% of active ingredient in a gum. Some people tend to eat them like candy, which quickly becomes expensive.
Energy compotes:
Energy compotes are a delicious and nutritious alternative to traditional energy bars and gels. These fruit purees, often enriched with cereals, seeds or even vegetables, are designed to provide a rapid and easily digestible release of energy. Their resealable bag format allows for convenient and quick consumption, ideal for athletes in full exercise. Rich in carbohydrates and sometimes boosted with vitamins and minerals, energy compotes provide not only an energy boost, but also essential hydration and nutrients to support performance and recovery. They represent an excellent option for those looking for a gentle and tasty source of energy, more practical to consume than a bar because they are liquid and more nourishing than a gel.
Energy drinks:
Energy drinks, also known as isotonic drinks or sports drinks, are specially formulated to support physical performance by providing very quickly assimilable carbohydrates and water. Typically available as a powder for dilution, they contain a balanced blend of carbohydrates, sodium and other essential minerals, facilitating the rapid absorption of fluid and energy by the body. These drinks are ideal for athletes during extended training or competitions, helping to maintain fluid balance and prevent fatigue. Their consumption helps optimize performance and promote faster recovery, making them a preferred choice for athletes of all levels.
Dried fruits :
Dried fruits are valuable allies for athletes, offering a concentrated and sustainable source of energy during exercise. Rich in natural carbohydrates, they provide a rapid energy supply, essential to support endurance and performance. Additionally, dried fruits are an excellent source of minerals like potassium and magnesium, which play a crucial role in preventing muscle cramps and improving recovery. Their small size and ease of transport make them particularly practical for long training sessions or competitions, where every second counts. By integrating dried fruits into your sports diet, you not only benefit from a rapid energy boost, but also from a supply of essential nutrients to optimize your performance and general well-being.
Whatever form you choose, pay close attention to the ingredients listed on the packaging. Do not buy products containing products that seem unnatural to you and those that contain synthetic sweeteners, preservatives and other flavorings. This will help you avoid possible digestive problems during exercise.
Finally, everyone will tell you that it is not recommended to consume a new product during a race without having tested it in training first.
How much carbohydrate is recommended during exercise?
The recommended amount of carbohydrates during exercise varies depending on the intensity and duration of the activity, but there are general guidelines that can help optimize performance and endurance. For long-term efforts (more than an hour), it is recommended to consume between 30 to 60 grams of carbohydrates per hour. This intake helps maintain blood glucose levels and delay the depletion of muscle glycogen stores.
For very long efforts (more than 2.5 to 3 hours), such as in the case of marathons or triathlons, consumption can be increased up to 90 grams of carbohydrates per hour, using multiple carbohydrate sources to promote better absorption and minimize the risk of gastrointestinal disorders.
It is important to personalize intake based on your body's reactions and experiences during workouts, as carbohydrate tolerance can vary greatly from person to person. Furthermore, it is advisable to start consuming carbohydrates early in the exercise and continue at regular intervals to maintain a stable energy intake.
To conclude, glycogen plays a vital role in sports performance , acting as a crucial source of quickly mobilized energy to support the intensity and duration of physical efforts. Properly managing glycogen stores through an appropriate diet and supplementation strategy can make a noticeable difference in achieving athletic goals, whether for regular training or competitions. By better understanding glycogen dynamics and optimizing its replenishment, athletes can not only improve their performance, but also their ability to recover and prepare for their future challenges.
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