The relationship between performance and energy use: Cystine utilizes lipids as an energy source to reduce fatigue
1. Let's think about how the energy used for exercise is generated in the body!
There are a variety of nutrients in the food we eat every day including carbohydrates, lipids, and proteins (amino acids). These nutrients are used to produce the energy needed daily by the body (Fig. 1).
Nutrients are used as energy sources. However, they cannot be used in the same form. Instead, they need to be converted into a substance called ATP (adenosine triphosphate).
The mitochondria are factories that produce ATP from nutrients. In other words, depending on the function of the mitochondria, the amount of energy produced will change.
The main sources of energy for exercise are carbohydrates and lipids. In endurance sports, a lot of energy is consumed. Effective use of these two energy sources is important for performance improvement. During exercise, glycogen (a carbohydrate that can be stored) in the body is conserved using more fatty acids formed from lipid breakdown as an energy source.
In other words, increasing the usable energy source may help to increase endurance. To that end, enhancing the function of the mitochondria that produce ATP can lead to optimum performance.
2. Can exercise-induced stress reduce the energy produced?
Continuous exercise may increase the amount and function of the ATP-generating factories, mitochondria. Increased activity of mitochondria in muscle cells increases the amount of ATP produced. In other words, increased mitochondrial function leads to increased endurance performance (Fig. 2).
However, stress induced by exercise naturally counteracts the functions of mitochondria. If the mitochondria are stressed, their function will be reduced. This reduces the amount of ATP produced by the mitochondria. The amino acid "cystine" can be used to avoid such problems as much as possible.
3. Can 'cystine' protect against exercise-induced oxidative stress?
"Cystine" consists of two "cysteines" bonded together. Cysteine is one of the 20 kinds of amino acids that make up proteins in the body. It is abundant in foods such as chicken and helps protect against various stresses (Fig. 3).
Cystine produces a substance called glutathione that protects the body from stress. Data is available showing that this glutathione protects the function of mitochondria, thereby enabling the use of lipids as energy sources and relieving fatigue during exercise.
We investigated the effect of cystine on the energy produced by muscles. As shown in the figure, cystine prevents a decrease in glutathione caused by oxidative stress. We also found that the amount of energy produced increases.
4. The possibility that cystine could use more lipids as energy sources!
Next, we examined the effects of cystine on fatty acid utilization during exercise in healthy males (Figure 4). In the group ingesting cystine, the amount of fatty acids in the blood was lower after exercise than that in the group that did not consume cystine.
This was thought to be the result of more fatty acids being utilized due to the increased use of fatty acids by cystine. In other words, cystine was considered to be effective in enhancing the utilization of fatty acids during exercise.
5. Taking cystine reduces fatigue during exercise!
We investigated the changes in fatigue during exercise as a result of cysteine using more fatty acids.
The question "how intense is the exercise you are doing?" was posed to healthy males while they exercised for about 1 hour.
As shown in Figure 5, the participants felt that the exercise was intense and the fatigue value increased as the duration of the exercise increased. However, after 25 minutes of exercise, the fatigue was less severe in the group consuming cystine than that in the group not consuming cystine.
In other words, consuming cystine may reduce fatigue during exercise and maintain performance.
6. Cystine helps increase the amount of energy available in the body!
Energy is essential for achieving optimum performance in any kind of exercise. For utilization of nutrients from the diet as energy sources by the body, mitochondria synthesize ATP. However, stress exerted on the body during exercising weakens this function. The effect of this stress is controlled by the amino acid cystine, which enhances mitochondrial function and increases energy availability, thereby reducing fatigue during exercise.
Enhancing endurance is one of the key issues for sportspersons. In sports when you want to perform well, in addition to training, the use of energy generated by cystine will help!