This is a very serious topic. It is not enough for you and me to understand the consumption of fat. This depends on researchers' research to know how to consume body fat. Many so-called fitness experts talk big without looking at many authoritative sports nutrition. I disagree with them very much. Saying bad things is "misleading children". The principle is not based on the training experience of bodybuilders, but on scientific research. It is simply wrong to extract a so-called "fat-burning Bible" on the Internet at will.
People often mistakenly think that fat burning occurs after glycogen exhaustion, which is also speculated by many "street fitness documents", but this is not the case. The following is a typical "street fitness" analysis:
We know the order of energy consumption in the body. There is blood sugar in the blood, glycogen in the liver, muscle glycogen in the muscle and fat layer under the skin. Under the condition of ensuring smooth breathing and adequate oxygen supply, low-intensity and long-term exercise will consume blood sugar first. When blood sugar is exhausted, liver glycogen and muscle glycogen will be decomposed into blood and continue to supply energy. When glycogen is exhausted, fat will begin to decompose and supply energy. At this time, it is the initial stage of weight loss, and you will feel whole body fever, itchy skin and slight sweating.
At first glance, it looks like that, but it is full of loopholes and can't stand scrutiny. The order of body energy consumption is based on which authoritative data? How to define it as low-intensity exercise? The whole body is hot, the skin is slightly itchy and sweating. It's not that no one has done aerobic exercise, so he looks mysterious, much like martial arts novels, which is really surprising.
Myth 1: The so-called body energy consumption order mentioned above. First, let's take a look at how aerobic exercise uses sugar and fat in the body. There is no order at all. Please look at the figure, which describes the consumption ratio of muscle glycogen, muscle triglyceride (fat), plasma free fatty acid (fat) and glucose (blood sugar) under different exercise intensities. It can be clearly seen that when the exercise intensity is 65%VO2max (the maximum oxygen supply is 65%), the ratio of triglyceride in muscle to free fatty acid in plasma is the largest. In fact, under the intensity of 25%VO2max exercise, the oxidation rate of total fat and sugar has little change after 30 minutes of exercise compared with that after 2 hours. However, under 65%VO2max exercise intensity, the amount of fatty acids released into blood and the utilization rate of blood sugar increased with time. After cycling for 2 hours at this exercise intensity, the oxidation rate of fat and sugar has no change compared with that after 30 minutes of exercise.
It can be seen that there is always fat energy in aerobic exercise, which is not the so-called exhaustion and then consumption of another.
Myth 2: Low-intensity long-term exercise burning fat is not correct. The best way to burn fat is moderate intensity aerobic exercise. This definition is based on the maximum oxygen supply. We get that the maximum oxygen uptake of 65% has the best fat burning effect. If the strict definition of intensity is 50%VO2max, then 65% is on the upper side, but generally speaking, it is moderate intensity aerobic.
Myth 3: When glycogen is exhausted, fat begins to decompose to provide energy. Based on the above analysis, we have come to the conclusion that the second half sentence is wrong, and then look at the first half sentence. First, let's recall how muscles produce movements. All muscle movements are produced by neural control. Then we can actually understand that motor nerve center fatigue or muscle fatigue will cause this system to "stop". The biochemical mechanism of fatigue is as follows:
Depletion of creatine phosphate in muscle;
Proton accumulation in muscle;
Accumulation of phosphoric acid in muscle;
Glycogen in muscle is exhausted;
Hypoglycemia;
The change of key amino acid concentration in blood leads to the change of neurotransmitter concentration in brain.
In middle-distance exercise, ATP is produced by aerobic and anaerobic exercise, and bodybuilders can make the aerobic system reach the maximum exercise capacity, which has been limited by muscle oxygen supply. At this time, ATP can be further produced by converting glycogen into lactic acid. If this state is maintained for a period of time, fatigue will occur due to glycogen depletion or proton accumulation in muscles. As for the specific situation, it depends on the intensity and time of exercise, the training level and adaptability of bodybuilders. If glycogen is converted into lactic acid faster than the proton scavenging ability in muscle, the accumulation of protons in muscle will lead to exercise fatigue. So for bodybuilders, improving glycogen storage and muscle's ability to recognize protons can prolong fatigue.
So now the conclusion is very clear. Muscle glycogen depletion. Actually, my muscles are completely tired. Can you still have strength to continue aerobic exercise after fatigue?
Finally, can you tell the true fitness experts from the false ones? I believe it is difficult for many bodybuilders to tell the difference. The only way is to study more, so as to see through who is talking nonsense at a glance. But then again, if everyone knows, who will care about those so-called "fitness experts"? As for how to distinguish true knowledge from false style, you should keep your eyes open. Although I'm not an expert in sports nutrition, I don't know and I'm not familiar with it. Finally, thank you for reading the last nonsense I wrote.
References:
Moen's Sports Nutrition (UK)
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