The energy needed for cellular functions during rest and muscular exertion is obtained by the body from carbohydrates, fats and proteins.
Energy for muscle work can be created anaerobically, by the process of glycolysis, where glucose or glycogen is exclusively broken down, or aerobically, by the Krebs cycle, where the metabolic products of glycolysis are used together with fatty acids through the process of beta oxidation. When the body is at rest, most of the energy (about 60%) comes from burning fat, while a significantly smaller (about 35%) proportion of carbohydrates comes from carbohydrates. The remaining 5% comes from protein. During muscular exertion, the relative share of fuel in the production of energy required depends on the intensity and duration of exercise, as well as the athlete’s diet and training level.
The role of fat
Fats are the ideal form through which cells can store and consume energy. One gram of fat contains about 9 kcal, twice as much as one gram of protein or carbohydrates. Fats are stored in the form of triglycerides in muscle cells (about 500 g) and adipocytes (about 14,000 g), while a negligible amount (0.4 g) is in plasma in the form of free fatty acids.
Although in recent literature there have been theses that speak in favor of the intake of large amounts of fat (intake of 30% or more of total calories), it should be emphasized that fats are a highly concentrated source of energy that does not lead to an improvement in sports performance when consumed in large quantities. There is no relevant scientific information to suggest that fat intake above 25% of total calories is generally beneficial for athletes.
From an exercise standpoint, it has not been proven that increasing fat intake results in improved athletic performance, unless increased fat intake is the only way for an athlete to get enough energy. Athletes who need more than 4,000 kcal each day to meet the combined needs of growth, exercise, and tissue regeneration may need a moderate increase in dietary fat intake (preferably plant or fish). Since fat is a more concentrated form of energy than both carbohydrates and proteins, more energy can be consumed in smaller amounts of food if the foods contain more fat. If an athlete tried to cut out fat intake altogether, he would have to consume so much food that it would become impossible to organize enough meals or set aside enough time for meals to consume the necessary energy. Because athletes store more calories from fat than from carbohydrates, an increase in the ability to use fat causes a proportional reduction in carbohydrate reliance, thereby increasing endurance. Simply put, if more fat is burned at a higher intensity of exercise, the carbohydrate reserves will last longer, thus improving endurance.
Fat oxidation, therefore, can never reach such a level as to eliminate the need for carbohydrates (glycogen) during intense exercise. Therefore, the greater ability to metabolize fats for energy should not direct athletes to increase their proportional fat intake. Assuming that the level of caloric intake is adequate, athletes can produce and store the fat they need, and a higher dietary fat intake is a clear risk factor for the occurrence of atherosclerosis heart disease. Even a short-term increase in fat intake with an accompanying decrease in carbohydrate intake for only 3 to 5 days causes a decline in endurance parameters when compared to the ability at a high carbohydrate intake. As for triglycerides, for most athletes, the maximum intake of medium-chain triglycerides should not exceed 30 grams (270 kcal). Intake above this amount greatly increases the risk of gastrointestinal disorders, including diarrhea.
In recent years, more and more attention has been paid to the possible beneficial effects of omega-3 fatty acids in improving performance in sports. The intake of omega-3 fatty acids has positive effects by enhancing aerobic metabolic processes, which has a positive effect on both the results of athletes and the ability of an individual to effectively use fats as energy fuel. This is not to say that increasing total fat intake is desirable or necessary to achieve the aforementioned beneficial effects, but athletes can consider changing the type of fats they consume in their diet by including periodic but regular (once or twice a week) meals of salmon, albacore tuna, Atlantic herring and other cold deep sea fish in the amount of 110 to 140 grams to increase the proportion of omega 3 fatty acids available to them. Other studies that have examined the effects of omega-3 fatty acids have found no consistent improvements in strength and endurance, nor evidence that omega-3 fatty acids reduce muscle soreness.
