The cause of fatigue for heavy, explosive lifting will be significantly different from the marathon runners fatigue. Fatigue never has a single cause. Coaches and athletes need to understand that there are many factors that contribute to a process called glycolysis which significantly impacts energy production.
The lactic energy system produces ATP by breaking down glycogen through:. Aerobic Glycolysis with oxygen - this contributes the glycolitic energy production and hence aerobic fitness levels have a significant role to play. Lactate is always produced as a by-product of carbohydrate metabolism, both aerobically and anaerobically, but lactate only accumulates when the aerobic energy system can not keep up with the rate at which lactate is being produced.
Pay attention to the magnesium demands on energy production, a good reason why athletes must supplement with magnesium to improve performance. There are four key steps involved in the anaerobic glycolytic system.
Steps of the anaerobic glycolytic system:. Initially, stored glycogen is converted into glucose. Glucose is then broken down by a series of enzymes.
Investment phase. Without aerobic input, the muscle becomes increasingly acidic as more hydrogen ions are created. Pyruvate is a byproduct of ATP and it can be used to fuel either the aerobic metabolism Krebs Cycle and Electron Transport Chain ETC we will talk about these in future posts or it can be used to produce lactate.
Lactate is always being produced, but when the aerobic energy system is functioning at a high level relative to the anaerobic demands, lactate is quickly oxidised back to pyruvate with can then be used to fuel further anaerobic metabolism.
This is where it can get a little confusing, but to keep it simple let's just say that the moderate levels of energy produced by the anaerobic lactic system can be supported by the aerobic energy system. The anaerobic and aerobic fitness levels of the athlete dictate how efficient the anaerobic lactic system works.
If lactate starts to accumulate in the muscle this indicates that the aerobic energy system can not recylcle the pyruvate as quick as the anaerobic lactic system is producting it. The body can try to shuttle the lactate around to other working muscle in other areas that can then try to convert it and utilise it.
This lactic shuttling allows for greater metabolic flexibility and increases the overall athletic performance of the athlete. We can think about the lactate energy system as a bridge between anaerobic energy production and aerobic energy production that allows the body to produce higher rates of force and power than it could if only the ATP-CP and the aerobic system were used.
The anaerobic lactic system can be developed through the correct training principles, as the total energy capacity is dependent on a host of factors like such as training background, genetics, and nutrition. Training the lactic system must be aimed at increasing tolerance to lactate, the removal of lactate and improving the rate at which glycolysis produces ATP. The aerobic system is slowly contributing an increasing percentage of ATP the longer the moderate intensity work period continues more on this later.
This is why it becomes increasingly important to separate anaerobic lactic and aerobic energy system training if you want to increase anaerobic power and overall fitness levels.
When training the lactic energy system the work to rest ratios vary depending on the intended outcome. Adenosine triphosphate is composed of adenosine and three phosphate groups. Adenosine is the combination of adenine a nitrogen base and ribose a five carbon sugar.
The breakdown of one molecule of ATP to yield energy is known as hydrolysis, because it requires one molecule of water. This adduct is classified as a high energy molecule because it stores large amounts of energy in the chemical bonds of two terminal phosphate groups. Equation 1: hydrolysis of ATP. We know two types of the metabolism anaerobic and aerobic. Anaerobic processes do not require the presence of oxygen. The phosphagen system and first phase of glycolysis fast glycolysis are anaerobic mechanisms that occur in the sarcoplasm of a muscle cell.
The Krebs cycle, electron transport, and the rest of the oxidative system slow glycolysis, the oxidative system are aerobic mechanism that occur in the mitochondria of muscle cells and require oxygen as the terminal electron receptor. Phosphate system provides energy for a very short time at the beginning of motor activity through the hydrolysis of ATP resources and decomposition of CP creatine phosphate. Fast glycolysis uses carbohydrates as a substrate for creating ATP during high-intensity activities without the presence of oxygen.
The final product of fast glycolysis is pyruvate which is furter converted to lactate. Slow glycolysis uses carbohydrates as a substrate for creating ATP during medium- and low-intensity activities where pyruvate, the final product of glycolysis, is not converted to lactate but it is transported to mitochondria where they are subject to Krebs Cyclus.
Slow glycolysis is conditioned by a sufficient amount of oxygen. Oxidative system uses fats as a substrate for creating ATP during low-intensity activities where fats enter the Krebs Cycle directly provided there is a sufficient amount of oxygen. Of the three main macronutriens carbohydrates, proteins, and fats only carbohydrates can be metabolized for energy without direct involvement of oxygen.
Therefore, carbohydrates are critical during anaerobic metabolism. All tree energy systems are active at any given time. The magnitude of the contribution of each system to overall work performance is primarily dependent on the intensity of the activity and secondarily on duration.
The phosphagen system provides ATP primarily for short-term, high-intensity activities e. This energy system relies on the hydrolysis of ATP and breakdown of another high-energy phosphate molecule called creatinephosphate CP. The creatine kinase reaction provides energy at a high rate. CP is stored in relatively small amounts; the phosphagen system cannot be the primary supplier of energy for continuous, long duration activities.
ATP in the body stores approximately 80 to g of any given time, which does not represent a significant energy reserve for exercise. Therefore, the phosphagen system, through CP and the creatine kinase reaction, serves as an energy reserve for rapidly replenishing ATP.
Another important single-enzyme reaction then can rapidly replenish ATP is the adenylate kinase also called myokinase reaction:. This reaction is particularly important because AMP a product of the adenylate kinase myokinase reaction is a powerful stimulant of glykolysis.
The reactions of the phosphagen system are largely controlled by the law of mass action. The law of mass action states that the concentrations of reactants or product or both in solution will drive the direction of the reaction. For example, as ATP is hydrolyzed to yield energy necessary for exercise, there is a transient increase in ADP concentration in the sarcolemma.
This will increase the rate of creatine kinase and adenyle kinase reactions to replenish the ATP supply. Glycolysis is the breakdowns of carbohydrates-either glycogen stored in the muscle and in the liver or glucose delivered in the blood-to resynthesize ATP. The process of glycolysis involves multiple enzymatically catalyzed reaction. As a result, the ATP resynthesis rate during glycolysis is not as rapid as with phosphagen system; however, the capacity is much higher due to a larger supply of glycogen and glucose compared to CP.
As with the phosphagen system occurs in the sarcoplasm. When pyruvate is converted into lactate, ATP resynthesis is slower and it depends on the intensity and duration of motor activity. This process is called anaerobic glycolysis fast glycolysis. When pyruvate is transferred into mitochondria to enter the Krebs Cycle, the speed of ATP resynthesis is slower but it can last for longer time if the intensity of exercise is medium.
This process is often referred to as aerobic glycolysis slow glycolysis. In other situations, energy does not have to be provided at as high of a rate, but must be supplied over a longer period of time.
Athletes who compete in sports that require high amounts of short duration intensity and acceleration will access this energy system. Shot-putters, weight lifters, football players, gymnasts, sprint-distance runners, or any athlete that utilizes explosive movements will utilize this energy system.
Training this system through strength and power exercises prolongs the ability to maintain a higher intensity. The anaerobic lactic AL system also known as fast glycolysis provides energy for medium to high-intensity bursts of activity that lasts from ten seconds to a max of approximately 90 seconds.
The ability to sustain this energy system is commonly viewed as an important athletic attribute in team sports such as basketball, hockey, ringette, and soccer where shifts, or transitions, are a part of the game.
Individual sports that consist of rallies or routines such as tennis, figure skating, gymnastics and skiing utilize this system.
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