BASIC PHYSIOLOGY
The respiratory system brings oxygen into our bodies and rids us of excess carbon dioxide. Energy is gained from the breakdown of food materials (oxidation) by transporting oxygen from the lungs into the bloodstream. Once in the bloodstream the oxygen can then be distributed to the body’s cells, where it is used to unlock the energy from food. Alveoli are tiny sacs which fill with air during breathing and it is at this wall that oxygen is exchanged from the lungs to the blood (vessels called capillaries). These narrow blood vessels have the job of transporting the oxygen via the bloodstream to the cells where it is used to unlock the energy from food. Carbon dioxide is the waste product from the process of oxygen combusting with food in cells to release energy.
STATISTIC – Oxygen makes up approximately 21% of the total gases found in the air we breathe.
The heart pumps blood around the body and on average it will beat 70 times per minute and each beat pumps 140ml of blood.
Muscles need energy to function. This energy is derived from the breakdown of various substrates (fat, carbohydrate and protein). Aerobic energy production refers to the process of energy production using oxygen to fuel low intensity endurance activities, such as; walking, jogging and running at low to moderate speeds. This type of energy production can be improved as a result of endurance training and is critical to provide a footballer with a strong fitness base from which he/she can improve other aspects of their overall fitness. Improvements in the body’s ability to produce energy aerobically increases the body’s ability to recover from physical activity.
In periods of intense exercise, oxygen being transported to the muscles is not always sufficient for aerobic energy production alone to meet these energy demands. In these instances energy is also produced in the absence of oxygen, namely through anaerobic energy production. A high anaerobic capacity is important for sustaining periods of high intensity exercise such as repeatedly performing sprints with limited recovery periods. The anaerobic capacity of each individual is variably different, however, the ability to perform explosive movements, such as sprinting, only lasts for about 10 seconds.
In the first 2 seconds of muscle contraction, Adenosine Triphosphate (ATP) is broken down within the muscle to use as the energy source. This short burst of energy would not be enough for the athlete to perform continual explosive movements, so a substance called Phosphocreatine (PC), also stored in the muscles, helps to resynth esize the ATP allowing more dynamic movement to take place. The low stores of Phosphocreatine only allows for 10 seconds of anaerobic activity. This is known as the ATP-PC system.
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