Differences between aerobic and anaerobic interval training (2023)

Interval training is a training method in which you increase and decrease the intensity of your training between aerobic and anaerobic training (KRAEMER & RATAMESS, 2004; Talanian, Galloway, Heigenhauser, Bonen, & Spriet, 2007). Interval training in Sweden, where some say it originated, is known as fartlek training (Swedish for “quick game”) (Ferraz et al., 2010). The interval training protocol is a well-known method of improving fitness (Dunham, 2010). Technically, it is defined as high-intensity intermittent exercise. In an interval session, periods of high-intensity work are interspersed with rest intervals. The objective of this training is to improve muscular performance (speed, strength and endurance) (Buchheit et al., 2009).

Interval training has been the mainstay of athletic training routines for years (Suh, Rofouei, Nahapetian, Kaiser, & Sarrafzadeh, 2009). The first forms of interval training, called “fartlek”, consisted of alternating short and fast bursts of intensive exercises with slow and easy activities (KRAEMER et al., 2004).

Interval training works both the aerobic and anaerobic systems. During high-intensity exertion, the anaerobic system uses energy stored in muscles (glycogen) for short periods of activity (Wells, Selvadurai, and Tein, 2009b). Anaerobic metabolism works without oxygen. The byproduct is lactic acid, which is related to the burning sensation felt in muscles during high-intensity exertion (Muscle & Production, 2009). During the high-intensity interval, lactic acid builds up and the athlete goes into oxygen debt. During the recovery phase, the heart and lungs work together to "pay off" this oxygen debt and break down lactic acid. It is in this phase that the aerobic system is in control, using oxygen to convert stored carbohydrates into energy (Wells et al., 2009b).

Aerobic exercise and physical conditioning can be contrasted with anaerobic exercise, of which strength training and sprinting are the most prominent examples (Delextrat & Cohen, 2008). The two types of exercise are differentiated by the duration and intensity of muscle contractions involved, as well as the way energy is generated within the muscle. Initially, during aerobic exercise, glycogen is broken down to produce glucose, which then reacts with oxygen (Krebs cycle) to produce carbon dioxide and water, releasing energy. In the absence of these carbohydrates, the metabolism of fats begins. The latter is a slow process and is accompanied by a decrease in the level of performance (Mansouri, 2009).

Aerobic exercise comprises numerous forms. It is usually performed at a moderate level of intensity for a relatively long period of time (Reid et al., 2010). For example, running a long distance at a moderate pace is aerobic exercise, but running is not. Playing individual tennis, with almost continuous movement, is generally considered an aerobic activity, whereas two-person team golf or tennis, with short bursts of activity punctuated by more frequent breaks, may not be predominantly aerobic.

The word anaerobic literally means without oxygen. Anaerobic exercise means that you are working at such a high intensity level that the cardiovascular system cannot deliver oxygen to the muscles quickly enough. Muscles trained with anaerobic exercise develop differently than with aerobic exercise, leading to greater performance in short-duration, high-intensity activities lasting from a few seconds to approximately 2 minutes. Any activity after about two minutes will have a large aerobic metabolic component (Scott, 2008).

To understand the physiological differences between aerobic and anaerobic exercise, one must be familiar with the body's energy sources (Meckel, Machnai, & Eliakim, 2009). Carbohydrates, including sugars, starches, and fiber, are the body's preferred source of energy, are the only fuel capable of being used by the central nervous system, and are the only fuel that can be used during anaerobic metabolism (Hargreaves, 2008; Dosil and Crespo, 2008). Carbohydrates are converted to glucose and stored in muscle cells and liver as glycogen, with approximately 1200 to 2000 kcal of energy stored as carbohydrate. Each gram of ingested carbohydrate produces approximately 4 kcal of energy (Hargreaves, 2008).

Fat can also be used as a source of energy and is the body's largest potential energy store, about 70,000 kcal in a lean adult. However, the basic storage form of fat useful as an energy source, triglycerides, must be broken down into free fatty acids (FFAs) and glycerol before FFAs can be used to form ATP via aerobic oxidation. The process of lowering triglycerides, called lipolysis, requires significant amounts of oxygen, so carbohydrate fuel sources are more efficient than fat fuel sources and are therefore preferred during high-intensity exercise. Of each gram of fat, 9 kcal of energy are produced (Hargreaves, 2008; Dosil et al., 2008).

Protein is used as an energy source in cases of starvation or extreme energy depletion, providing approximately 5% to 10% of the total energy needed for endurance exercise. Protein yields approximately 4 kcal of energy per gram and is not a preferred energy source under normal conditions (Hargreaves, 2008; Dosil et al., 2008).

In the human body there are three metabolic pathways to produce energy (Wells, Selvadurai, & Tein, 2009a).

sistema ATP-PCr

The first pathway is anaerobic, meaning it does not require oxygen to function, although it can also occur in the presence of oxygen. This pathway is called the ATP-PCr system, where PCr stands for creatine phosphocreatine or creatine phosphate. Like ATP, PCr is a high-energy compound found in skeletal muscle cells that works to replenish ATP in a working muscle, extending time to fatigue by 10 to 20 seconds. Therefore, the energy released as a result of PCr degradation is not used for cellular metabolism, but rather to prevent falling ATP levels. One ATP molecule is produced per PCr molecule (Barrett, 2009). This simple energy system can produce 3 to 15 seconds of peak muscle work and requires adequate recovery time, typically three times the duration of the activity.

Glycolytic System

ATP production during long periods of activity, such as those needed to treat impaired aerobic capacity, requires the breakdown of dietary energy sources. In the glycolytic system, or during anaerobic glycolysis, ATP is produced by the breakdown of glucose obtained by ingestion of carbohydrates or by the breakdown of stored hepatic glycogen. Anaerobic glycolysis also occurs, without the presence of oxygen, but it is much more complex than the ATP-PCr pathway and requires numerous enzymatic reactions to break down glucose and produce energy (Bhise, 2008). The end product of glycolysis is pyruvic acid, or pyruvate, which is converted to lactic acid in the absence of oxygen, and the net energy output of each glucose molecule used is two molecules of ATP or three molecules of ATP from each molecule. of glycogen. . Although the energy output of the glycolytic system is small, the combined energy output of the ATP-PCr and glycolytic pathways allows the muscles to contract without a continuous supply of oxygen and therefore provides a source of energy in the early part of the workout. of high intensity. exercise until the respiratory and circulatory systems meet the sudden increase in demand placed on them. Furthermore, the glycolytic system can only supply energy for a limited time because the end product of the pathway, lactic acid, accumulates in the muscles and inhibits further breakdown of glycogen and ultimately prevents muscle contraction (Barrett, 2009 ).

Oxidative System

The production of ATP from the breakdown of fuel sources in the presence of oxygen is called aerobic oxidation or cellular respiration. ATP is produced in mitochondria, cell organelles conveniently located next to myofibrils, the contractile elements of individual muscle fibers. The oxidative production of ATP involves several complex processes, including aerobic glycolysis, the Krebs cycle and the electron transport chain (Bhise, 2008).

Carbohydrates or glycogen are broken down in aerobic glycolysis, similar to the breakdown of carbohydrates in anaerobic glycolysis, but in the presence of oxygen, pyruvic acid is converted to acetyl coenzyme A (acetyl Co-A). Acetyl Co-A undergoes a series of complex chemical reactions in the Krebs (citric acid) cycle, producing two molecules of ATP (Fig. ). The end result of the Krebs cycle is the production of carbon dioxide and hydrogen ions, which enter the electron transport chain, undergo a series of reactions, and produce ATP and water.

The difference between aerobic and anaerobic exercise can be summarized as follows:

The literal meaning of aerobics is oxygen. Therefore, aerobic exercise can be defined as that which involves using oxygen to produce energy, while anaerobic exercise causes the body to produce energy without using oxygen.

Anaerobic exercises are high intensity exercises that are done for a short period of time. In contrast, aerobic exercises are generally easy exercises and are done for a longer time at a moderate intensity.

A person doing aerobic exercise requires more endurance, because unlike anaerobic exercise (which is done for a short period), aerobic exercise is done for a long time.

Generally, aerobic exercise is done for about 20 minutes or more. On the other hand, the duration of an anaerobic exercise is two minutes, which can only be maintained longer with proper training.

The metabolic processes utilized by aerobic and anaerobic exercise differentiate them. While both aerobic and anaerobic exercise produce energy through glycolysis (conversion of glucose to pyruvate), the substance used to break down glucose is different. While oxygen is used to break down glucose through aerobic exercise, anaerobic exercise uses phosphocreatine, stored in the muscles, for the process.

Aerobic and anaerobic exercises are performed to achieve individual goals. Aerobic exercises focus on strengthening the muscles involved in breathing. It improves blood circulation and oxygen transport in the body, lowers blood pressure and burns fat. On the other hand, anaerobic exercise helps build strength and muscle mass, stronger bones and increases speed, power, muscle strength and metabolic rate. It focuses on burning calories when the body is at rest.

When performing aerobic exercises, you will notice an increase in heart rate and an increase in the level of breathing. Energy is provided by carbohydrates and fats when muscles work. On the other hand, the sources of energy during anaerobic activity are adenosine triphosphate (ATP) and creatine phosphate.

There are some acute and chronic changes after aerobic exercise. The repetitive form of training leads to the adaptive response. The body begins to build new capillaries and is better able to absorb and deliver oxygen to working muscles. The muscles develop a greater tolerance for lactate accumulation and the heart muscle becomes stronger. These changes result in better performance, particularly in the cardiovascular system.

The ability to sustain aerobic exercise depends on numerous cardiovascular and respiratory mechanisms designed to deliver oxygen to tissues. The following changes would be expected during aerobic exercise and would be considered normal responses.

heart rhythm

There is a linear relationship between heart rate (HR), measured in beats/min, and exercise intensity, indicating that as workload or intensity increases, HR increases proportionally. The magnitude of the increase in HR is influenced by many factors, including age, fitness level, type of activity performed, presence of illnesses, medications, blood volume, and environmental factors such as temperature and humidity.

hit volume

The volume or amount of blood ejected from the left ventricle per heartbeat is called stroke volume (SV), measured in mL/beat. As workload increases, SV increases linearly to approximately 50% of aerobic capacity, after which it increases only slightly. Factors that influence the magnitude of change in SV include ventricular function, body position, and exercise intensity.

cardiac output

The product of HR and SV is cardiac output (Q), or the amount of blood ejected from the left ventricle per minute (L/min) (Q = HR X SV). Cardiac output increases linearly with workload due to increases in HR and SV in response to increased exercise intensity. Changes in Q depend on age, posture, body size, presence of disease, and fitness level.

Arterial-venous oxygen difference

The amount of oxygen extracted from the blood by the tissues represents the difference between the oxygen content in arterial blood and the oxygen content in venous blood and is called the arterial-venous oxygen difference (a-vO2 diff), measured in ml/dl . As exercise intensity increases, the a-vO2 difference increases linearly, indicating that tissues are extracting more oxygen from the blood, with venous oxygen content decreasing as exercise progresses.

Blood circulation

The distribution of blood flow (ml) to the body changes dramatically during acute exercise. While at rest approximately 15% to 20% of cardiac output goes to muscle, during exercise approximately 80% to 85% is distributed to active muscle and bypassed the viscera. During intense exercise, or when the body begins to overheat, increased blood flow is sent to the skin to draw heat away from the body's core, leaving less blood for the working muscles.

Blood pressure

The two components of blood pressure (BP), systolic pressure (SBP) and diastolic pressure (DBP), respond differently during acute bouts of exercise. To facilitate the delivery of blood and oxygen to tissues, SBP increases linearly with workload. As the DBP represents the pressure in the arteries when the arteries are at rest, it changes little during aerobic exercise, regardless of the intensity. A change in DBP of less than 15 mm Hg from the resting value is considered a normal response.

Pulmonary ventilation

The respiratory system responds during exercise by increasing the rate and depth of breathing to increase the amount of air exchanged per minute (L/min). An immediate increase in speed and depth occurs in response to exercise and is believed to be facilitated by the nervous system, initiated by body movement. A second, more gradual increase occurs in response to body temperature and chemical changes in the blood as a result of increased tissue use of oxygen. Therefore, both the tidal volume, that is, the amount of air that enters and leaves the lungs during normal breathing, and the respiratory rate (RR) increase proportionally to the intensity of the exercise.

As a result, aerobic exercise can reduce the risk of death from cardiovascular problems. In addition, high-impact aerobic activities (such as running or jumping rope) can stimulate bone growth and reduce the risk of osteoporosis in both men and women.

In addition to the health benefits of aerobic exercise, there are numerous performance benefits:

• Increased storage of energy molecules such as fats and carbohydrates in muscles, allowing for greater endurance
• Neovascularization of muscle sarcomeres to increase blood flow through the muscles
• Increased rate at which aerobic metabolism is activated within muscles, allowing a greater portion of energy to be generated aerobically for intense exercise
• Improve your muscles' ability to use fat during exercise by preserving intramuscular glycogen
• Improve the rate at which muscles recover from high-intensity exercise

psychological benefits

There is compelling evidence that aerobic exercise can have psychological benefits. In addition to the cardiovascular and respiratory effects of exercise, the psychological and emotional benefits of exercise, such as well-being, treating insomnia, and reducing stress, have been well documented.

Abnormal responses to aerobic exercise

People with suspected cardiovascular disease or any other type of disease that may cause an abnormal response to exercise should be properly screened and evaluated before starting an exercise program. However, abnormal responses can occur in individuals with no known or diagnosed disease, and therefore routine monitoring of exercise response is important and can be used to assess the adequacy of exercise prescription and as an indication that additional diagnostic tests may be needed. indicated. In general, responses that are inconsistent with the normal response patterns described above are considered abnormal responses. Of the described parameters, HR and BP are the most frequently evaluated during exercise. Failure to increase HR proportionally to exercise intensity, lack of SBP increase, or a SBP decrease of 2:20 mm Hg during exercise and a DBP increase of 2:15 mm Hg would all be examples of abnormal responses to aerobic activity. exercise.