Fat/energy/performance/bodybuilding

Fat is the primary source of energy for any exercise lasting longer than 10 minutes. However, when describing the use of fat as an energy source, we must also consider the type of athletic performance. Especially when comparing typical aerobic (low intensity, continuous) and anaerobic (high intensity, short duration, albeit repeated) exercise.

The conversion of fat to energy is an oxygen demanding process for the body. Once we exceed our ability to deliver sufficient oxygen to the cells, we move into anaerobic exercise, where we use a "replacement source" in the form of increased sugar to perform. Since sugar stores are orders of magnitude lower than fat stores, high intensity exercise is not sustainable long term.

Fat and power

If you are interested in endurance performance, then fat is the overwhelmingly predominant energy source for multi-hour performances where heart rate is around 85% of maximum (marathoners, cyclists), and in the 50-60% range for less-trained populations.

The ability to utilize fat varies according to the athlete's training and muscular build. Thus, the following factors are even more critical for peak endurance performance:

• The content of so-called slow-twitch muscle fibers with greater fat storage and enzymatic equipment for energy processing
• High oxygen utilisation and oxygen absorption capacity (red blood cell count and more haemoglobin - this is the basis for the doping methods of endurance sport)
• High ability to tolerate catabolites produced (decomposition in the presence of oxygen)

In contrast, a strength athlete has a higher ability to work in oxygen debt and a higher ability to utilize sugars stored in the muscles. They may also have a shifted so-called lactate threshold - lactic acid is formed when sugar is burned.

However, it must be stressed that even purely aerobic exercise cannot be accomplished without some contribution from sugars. The once popular slogan "fats burn in the flame of sugars" applies.

Fat is the absolutely dominant source of energy only under conditions of physical rest - including sleep. As soon as physical activity occurs, sugars are burned.

There is yet another limitation in the use of fat. This is because the immediate use of subcutaneous and visceral fat, even in prolonged exercise, is demanding on the body. Therefore, we can say that although fat is available in orders of magnitude more than sugar, its usable reserves are also limited. Subcutaneous fat is metabolically inactive!

In terms of endurance performance, the same strategy we know from strength sports for supercompensation cannot be applied to fat. It is not possible to supersupply fat before exercise. Higher fat content in the diet will translate into an increase in poorly utilized subcutaneous fat stores. In addition, ketoacidosis can occur and an acidic environment is not intrinsic to the body. In addition, the ability to utilize proteins and sugars may be impaired. The only option is to use MCT fats as an energy source during exercise.

Bodybuilding and fat

From a bodybuilding perspective, the use of fat as an energy source is particularly important in competition training, when the bodybuilder is trying to eliminate subcutaneous fat stores through targeted physical exercise. Thus, the use of fat is not primarily for the purpose of performance, but for the sporting goal of enhancing the aesthetics of the body by removing it.

In the case where we are concerned with the use of fat already present in the body, our efforts will be targeted mainly in the purely aerobic zone, i.e. exercise in which there is a perfect supply of oxygen. Such exercise is in the intensity range not exceeding 60% of the maximum oxygen consumption or 70% of the maximum individual heart rate. In top endurance athletes, as we said, this limit moves to higher values. The bodybuilder, however, is certainly not one of the top endurance athletes.

From our bodybuilding point of view, it is essential that the main source of energy is the fat stored inside the muscle cell, not the subcutaneous or visceral fat (wrapping the organs). Even fat in the form of free fatty acids contained in the blood is not a significant source of energy for strength sports. The situation is different with free fatty acids in endurance exercise.

Thus, the aerobic activity of a bodybuilder aimed at devastating fat stores usable for performance is given by the 50-70% of the maximum individual heart rate zone.

The question that surely comes to mind is what about interval training that alternates intense phases above this band with phases of calming. The fat is applied precisely in the second phase of calming, i.e. in the breaks between loads. However, the break must be long enough, precisely because of the utilization of fats.

However, there is another argument for the use of a reasonable level of interval training or aerobic training in strength athletes than just the devastation of fat stores. For strength athletes to be able to complete a sufficiently demanding workout, they too must have sufficient oxygen capacity and also a strong heart. A higher "oxygen" capacity will reduce the time required for recovery and more consistently conserve their own muscle protein. As a result, they can train more often.

Even if you don't possess the advantages of an endurance physique and high oxygen capacity, the use of fat as energy can be optimized by using effective substances. The most effective of these is Carnitine. Fats are processed in the mitochondria in the presence of oxygen, but the fat must be transported to the mitochondria. Carnitine is the transporter.

This brings us to the bodybuilder's primary endeavor during the competition period, the devastation of subcutaneous fat stores. Up until now we have been concerned with the use of fat for performance, and we have found that subcutaneous fat is almost metabolically inactive!

Devastation of subcutaneous fat is an extremely time consuming process. Energy utilization of subcutaneous fat occurs when there is insufficient caloric intake through diet. If the fat is not also in the diet, for example, taken after a sporting event, the body is forced to replenish the necessary fat stores in the muscles from the stores in the subcutaneous tissue. It even takes several days for the process to fully kick in!

So, all this is good to know about fat if you are about to start losing fat accumulated in volume training. It is just such a period now.