The relationship between exercise and carbohydrate supplementation | How to utilize glycogen to improve endurance and performance

In order to maintain your ideal performance when exercising, it is very important to replenish carbohydrates as an energy source. Taking carbohydrates in the right way before, during, and after exercise will help you maintain and demonstrate your performance. In this article, we will explain why carbohydrates are necessary for athletes, the role of carbohydrates, and how to take them during exercise.

[Digest video] How to deal with fatigue at the end of exercise! Tips for replenishing carbohydrates / Learn with illustrations

Glycogen is an important source of energy during exercise

Our bodies use carbohydrates and lipids as the main sources of energy during exercise. Carbohydrates in particular are used more as the intensity of exercise increases, and as the carbohydrates in the body decrease, you become fatigued.

Carbohydrate replenishment and glycogen stores

When carbohydrates are consumed from food and absorbed into the body, they are transported throughout the body via the blood, including to the muscles and brain. As shown in Figure 1, when you are at rest, the carbohydrates you consume from food are stored in the muscles as glycogen, and are used as an energy source during exercise.

Glycogen storage capacity and characteristics

It is also stored in the liver as glycogen, but when blood glucose (blood sugar) decreases during exercise, it is converted back into glucose and used to maintain blood sugar levels.
The amount that can be stored as glycogen varies from person to person depending on factors such as muscle mass, but it is said that athletes can store approximately 2,000 kcal of glycogen, which is more than the average person (the amount of energy needed for an 18-29 year old male on a day when he is not very active is 2,300 kcal).

However, the amount of glycogen stored in the body is overwhelmingly less than that of lipids (fat). The average adult's body fat percentage is about 15%, which is less than one-thirtieth of the amount stored in a 60kg person, who stores about 9kg of lipids and about 65,000kcal (calculated at 1kcal per gram).

Figure 1
Ingested carbohydrates are stored as glycogen and used little by little.

Decreased glycogen levels lead to decreased performance

Because the amount of glycogen stored in the body is so small, if you exercise for a long period of time, your glycogen will run out at the end, causing your performance to decline.

For example, when marathon runners participated in a full marathon (Figure 2), their running speed decreased toward the end of the race. These runners were able to run at 12-12km/h from the start until the 13km mark, but their speed gradually decreased from the 16km mark, and by the 36km mark, their speed had dropped to less than 11km/h.¹⁾.

There is also data that measured the speeds that soccer players ran during a match. When the distances they ran at fairly fast speeds of 16 to 22 km per hour were measured, it was found that the distances they ran at high speeds, especially towards the end of the match (the last 15 minutes), were shorter than in the first half or immediately after the start of the second half.²⁾.

Figure 2
Declining performance in the final stages of endurance sports is an issue

1) Billat VL et al, ScientificWorldJournal. 2012 2012 810859
2) Mohr M et al, Scand J Med Sci Sports. 2010 Oct 20 Suppl 3 125-32

In this way, if you continue exercising for a long period of time, your performance will decrease towards the end. This is thought to be caused by the glycogen in your body being used up and depleted.

What is an effective way to replenish carbohydrates?

In order to prevent a slowdown in pace or a decline in performance, it is necessary to first make sure that glycogen stores in the body are not depleted during exercise by consuming carbohydrates in your regular meals and storing as much glycogen as possible in your body. Carbohydrates are found in large amounts in so-called grains such as rice and wheat.

Daily carbohydrate intake

2016年に発表されたアメリカスポーツ医学会（ACSM）のガイドラインでは、1日あたり1時間以内の中等度の運動を行う場合、体重1kgあたり5～7g、1～3時間くらいの強めの運動を行う場合には、6g～10g程度の糖質を毎日摂ることが奨められています³⁾In other words, if a person weighing 60 kg exercises for 1 to 3 hours, it is recommended that they consume 1 to 360 g of protein per day (equivalent to about 600 to 6 bowls of rice).

It is also recommended to take in carbohydrates before, during and after exercise, paying attention to the following points. Although it will vary depending on the athlete's situation, physical condition and the type of sport played, the following points can serve as a guideline (Figure 3).

Carbohydrate supplementation before exercise

The ACSM guidelines recommend consuming 1-4g of carbohydrates per kg of body weight (60-240g for a 60kg person) 1-4 hours before exercise.

Supplementing carbohydrates during exercise

For endurance sports that last 1 to 2.5 hours, it is effective to consume 30 to 60 grams of carbohydrates per hour. Taking into consideration the type of sport, how long the match or practice will last, and your physical condition on the day, it is recommended that you do not consume a large amount all at once, but rather consume it in small amounts over several sessions.

Carbohydrate replenishment after exercise

If you have a game or practice going on in succession throughout the day, you should immediately replenish carbohydrates and consider restoring the glycogen in your body. For the next day, be mindful of restoring glycogen and consider your daily carbohydrate intake and make sure to replenish it sufficiently through your meals.

Figure 3
It is effective to plan your carbohydrate intake according to your exercise schedule.

3) Thomas DT et al, Med Sci Sports Exerc. 2016 Mar;48(3):543-68

Utilizing amino acids to efficiently use carbohydrates

The function of amino acids is essential for efficiently converting carbohydrates into energy.
Ajinomoto Co., Inc. is focusing on alanine and proline, which have been shown to enhance glycogen production from carbohydrates, maintain blood sugar levels and stamina even during prolonged exercise. Applying this mechanism, the Alanine and Proline Carbohydrate Mix helps maintain performance in endurance sports such as marathons.

The role of carbohydrates, which are essential during exercise, and key points for intake

Below are some key points about carbohydrates, which are an important source of energy during exercise.

Carbohydrates are an important source of energy and are stored in the muscles and liver as glycogen.
During strenuous exercise, the glycogen in your muscles is used up and reduced.
In particular, at the end of a long exercise session, glycogen is depleted, causing fatigue.
Make sure to consume plenty of carbohydrates in your daily meals so that your glycogen stores do not run out during exercise.
Be sure to replenish your carbohydrate intake before, during, and after exercise.

Understand the role of carbohydrates during exercise, actively consume carbohydrates, and continue to perform satisfactorily.

A body that can move even in the final stages of a match. The power of carbohydrates and amino acids.

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"Alanine and Proline Carbohydrate Mix" supports the use of carbohydrates for energy, helping to maintain endurance.

<Supervisor>Shin Terada

Completed the doctoral program at the Graduate School of Human Sciences, Waseda University (PhD in Human Sciences). After working as a PD special researcher at the Japan Society for the Promotion of Science, a researcher at the University of Washington School of Medicine, a researcher at Sankyo Co., Ltd., a lecturer at the Waseda University Institute for Advanced Science and Health Care, and director at the Central Research Institute of Nisshin Oillio Group Co., Ltd., he will become a professor at the Graduate School of Arts and Sciences, the University of Tokyo, in 2023.