Aerobic exercise and substrate oxidation

Last reviewed by: Aleksey Portnov , medical expert, on 15.05.2018

Edible fats during the aerobic exercise preserve carbohydrates, enhancing the oxidation of fats and reducing the oxidation of carbohydrates. This reduction in the oxidation of carbohydrates can increase endurance due to the fats used to generate energy. It has been hypothesized that an increase in the intake of edible fats can increase the oxidation of fatty acids, save carbohydrates and improve other indicators. But the available data do not support this hypothesis.

Studies have shown that the infusion of triacylglyceride emulsion or the intake of saturated fatty acids does not affect the level of muscle glycogen during exercise, performance and other indicators. In addition, some researchers have used fasting, trying to increase the oxidation of fatty acids compared to carbohydrates under stress. And although starvation contributed to the oxidation of fatty acids during exercise, however, other indicators did not improve. The influence of diets with a low carbohydrate content and a high fat content on physical exercises and glycogen stores was considered. These manipulations with diets did not reveal the corresponding effects on muscle glycogen stores, performance and indicators.

At this stage, the effectiveness of short-term dietary manipulation, including a fat load to increase performance by enhancing fat oxidation and reducing oxidation of carbohydrates in athletes carrying a load on endurance, still requires evidence. On the other hand, long-term adaptation to a diet rich in fats can cause metabolic adaptation and / or morphological changes, which in turn can influence the performance.

According to observations of Lambert et al., Using a diet with 76% fat compared to a diet containing 74% carbohydrates, cyclists for 14 days did not worsen the maximum energy output and the time to exhaustion indicators. However, muscular glycogen stores were half as high in a diet high in fat as compared to a high-carbohydrate diet, which makes it difficult to interpret the effect of these dietary manipulations on endurance. Helge et al. Showed that untrained men on a diet high in fat (62% of energy) or on a high-carbohydrate diet (65% of energy) and a 40-week workout had a 9% increase in V02max, and the work time to exhaustion increased with both diets . Thus, adapting to a diet high in fat combined with training sessions for up to 4 weeks with submaximal loads does not worsen endurance, and a diet with a high fat content for 7 weeks was associated with a reduction in the time to exhaustion compared to the group on the diet high-carbohydrate diet. Therefore, it can be assumed that the length of stay on a diet high in fat affects the indicators.

This adaptation to edible fats can be associated with enzymes for the oxidation of fatty acids. A strong relationship was found between the activity of (3-hydroxyacyl-CoA dehydrogenase and the consumption and oxidation of fatty acids.In spite of this adaptation caused by training, an increase in endurance rates with an enhanced fat diet is not comparable with that observed with a high-carbohydrate diet.

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