PHYSICAL EDUCATION 2nd TERM PROJECT

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• WHAT IS THE METABOLISM?

Every sporting gesture or muscular contraction needs an energy that it obtains by the degradation of nutrients, this degradation is known as metabolism.

Metabolism refers to the processes your body uses to break down nutrients, form compounds the cells can use for energy and use those compounds to fuel cellular functions. Your body secretes enzymes to break down food into sugars, proteins, and fats. Then each cell of your body can take these in and use them in aerobic or anaerobic metabolic processes to form adenosine triphosphate (ATP) which is the fuel used in the cell. The calories from food are burned in this way to produce energy in each cell. Your body's overall metabolism includes muscle contraction, breathing, blood circulation, maintaining body temperature, digesting food, eliminating wastes, and the functions of the brain and nervous system. The rate at which you burn calories is called your metabolic rate.

During exercise, you not only increase metabolism in your muscles but also in your respiratory and circulatory systems. You need a faster rate of breathing and heart rate to deliver oxygen and nutrients to your muscles. Your body also must work harder to prevent overheating, such as through sweating.

Our body uses two types of metabolism during exercise to provide the fuel needed for your muscles: AEROBIC and ANAEROBIC.

• WHAT IS THE AEROBIC METABOLISM?

It's the way your body creates energy through the combustion of carbohydrates and fats in the presence of oxygen. Combustion means burning, which is why this is called burning (sugars, fats...) for getting the energy.

Exercises that use aerobic metabolism, are for example, walking, running... 

aerobic metabolism fuels most of the energy needed for long duration activity. It uses oxygen to convert nutrients (carbohydrates, fats, and protein) to ATP. This system is a bit slower than the anaerobic systems because it relies on the circulatory system to transport oxygen to the working muscles before it creates ATP. Aerobic metabolism is used primarily during endurance exercise, which is generally less intense and can continue for long periods of time.

As exercise begins, ATP is produced via anaerobic metabolism. With an increase in breathing and heart rate, there is more oxygen available and aerobic metabolism begins and continues until the lactate threshold is reached. If this level is surpassed, the body can't deliver oxygen quickly enough to generate ATP and anaerobic metabolism kicks in again. Since this system is short-lived and lactic acid levels rise, the intensity can't be sustained and the athlete will need to decrease intensity to remove lactic acid build-up.

In the aerobic metabolic process, the human body uses a molecule of glucose to produce 36 adenosine triphosphate (ATP) molecules. ATP is what fuels your muscles. Anaerobic metabolism, which is used for vigorous muscle contraction, only produces 2 ATP molecules per glucose molecule, so it is much less efficient.

There are three ways (they work simultaneously) of aerobic metabolism:

1. Glycolysis: Oxidates the glucose and releases energy (ATP molecules)
2. Krebs Cycle: Oxidates a molecule (Acetil-CoA) and releases energy (ATP molecules)
3. Electron transport chain: Different molecules are oxidated and releases energy (ATP molecules)

These processes can produce a lot of energy (32 ATP molecules) releasing CO2 and H2O

• WHAT IS THE ANAEROBIC METABOLISM?

Anaerobic metabolism is done by the combustion of carbohydrates. It uses nutrients due to the absence of oxygen. Unable to oxidize it, it uses another process, instead of the oxidation it uses the fermentation, which doesn´t oxidize, it reduces the nutrients for oxidate them later. This process produces a smaller number of molecules compared to the aerobic metabolism. The anaerobic metabolism produces 2 molecules of ATP.. Also produces energy and uses glucose, but it produces less energy and does not require oxygen. 

When there isn't enough oxygen in the bloodstream, glucose and glycogen can't be fully broken down to carbon dioxide and water. Instead, lactic acid is produced, which can build up in the muscles and degrade muscle function.

Lactid acid is a by-product of anaerobic glycolysis and anaerobic metabolism, both o which occur duing strebuous exercise. Although lactic acid is used as a fuel by the heart, an excessive amount of lactic acid in your skletal muscles slows down contractions, preventing you maintaining peak performance.

When your muscles use anaerobic metabolism, lactic acid is produced in your muscle cells. With modernate intensity exercice, it is able to difuse out of the cells, but with vigorous muscle contractions it builds up. As you build up more and more lactic acid, your muscles burn and are fatigued.

Often, this is felt in activities like wieght liftng, but you can reach it when running or cycling at a sprint. You are forced to back off and slow down so your muscles can recover and allow lactid acid to diffuse out of the cells. Lactid acid is further processed by the liver into glucose to use for fuel, completing the cycle.

Generally, this occurs only for short bursts of activity, such as when you do a sprint . When there isn't enough oxygen in the bloodstream, glucose can't be fully broken down to carbon dioxide and water. Instead, lactic acid is produced.

DIFFERENCES BETWEEN AEROBIC AND ANAEROBIC METABOLISM?

The main differences between AEROBIC and ANAEROBIC METABOLISM are:

• The key difference between the two is that aerobic metabolism occurs in the presence of oxygen, while anaerobic metabolism doesn't.

                                           

• The anaerobic metabolism is usually carried out at the beginning of the exercise, it´s generally used to do short but intense exercises. The aerobic metabolism occurs when the physical activity is prolonged and the organism needs more energy.
• Anaerobic metabolism is not as efficient as aerobic metabolism, aerobic metabolism produces more energy than anaerobic metabolism. A molecule of glucose can only produced 3 ATP molecules under anaerobic metabolism, while it produces 39 with aerobic metabolism. ATP is what fuels the muscles.
• Anaerobic metabolism can only uses glucose and glycogen, while aerobic metabolism can also break down fats and protein. Intense bouts of exercise in the anaerobic zone and exercises with a heart rate over 85, will result in using anaerobic metabolism to fuel the muscles.
• Anaerobic metabolism cannot continue indefinitely. In contrast, aerobic metabolism can continue forever, only under theoretical conditions.
• Carbohydrate, fat, and proteins are used as sources of aerobic metabolism while only carbohydrate is involved for anaerobic metabolism.
• Aerobic metabolism involves low to moderate intensity activities, whereas anaerobic metabolism involves only high intensity activities.
• Anaerobic metabolism takes place in the cytoplasm of cells while aerobic metabolism occurs in mitochondria.
• Aerobic metabolisms contribute more (around 90%) for the supply of energy while anaerobic metabolism contributes less.
• The final product of anaerobic metabolism is lactic acid while that of aerobic metabolism is carbon dioxide and water. 

• AEROBIC AND ANAEROBIC EXCERCISES

Examples of aerobic exercises include cardio machines, spinning, running, swimming, walking, hiking, aerobics classes, dancing, cross country skiing, and kickboxing. There are many other types.

Anaerobic workouts can consist of heavy squats, deadlifts and bench. Lifting weights. You need to take a break in between sets. Other examples of anaerobic sports and exercise include sprinting, high-intensity interval training and powerlifting.

Combining aerobic and anaerobic workouts? Of course!

Lots of athletic activities and certain exercises rely on both energy systems. Soccer, for example, requires an athlete to alternate between quick bursts of sprinting, which is anaerobic, and longer stints of jogging, which is aerobic.

Someone training for a marathon will rely primarily on the aerobic system while exercising. However, if they incorporate other methods of training during their workouts such as sprints or hill repeats, they will activate the anaerobic system (while going full force), before transitioning back to the aerobic system as soon as steady-state running resumes.

• CONCLUSIONS

When we practise a sport or we make excercise activities, our body changes from one metabolim to another depending on what it needs in that moment.

Anaerobic metabolism is not as efficent as aerobic metabolism is; but, on other way, the anaerobic one can only use glucose and glycogen, while aerobic can also use fats and protein.

But, after all, our body is able to choose between them and use the one that adapts better to what it needs at that moment, which in my opinion is so interesting. Definitely, this was a completely unknown topic for me, but by doing this project, I've learnt more thing about how our body works.

In addition to Victor's blog's video, here is another one that I think is pretty interesting. Click HERE to watch it!