Key systems are respiratory, muscular, cardiovascular and energy systems. The respiratory system is responsible for the intake of oxygen. When we breathe in we draw in air. Oxygen, which comprises 21% of the air’s composition, is then absorbed into the bloodstream via the alveoli. The oxygen then acts to release energy from the good we take in, and provide the body with energy. At any one time there is about 7 minutes worth of oxygen in our body. If we stop breathing this is the approximate amount of time we have before permanent brain damage is caused. The offshoot of this energy release is carbon dioxide which is then expelled by the reverse process as we breathe out.
The cardiovascular system includes our heart and blood vessels. It is the method by which oxygen is carried from the lungs to the rest of the body. It also carries nutrients and other healing agents (e.g. white blood cells, platelets etc). The heart can usefully be divided into two halves. The right half receives deoxygenated blood from the body. It is sent to the right ventricle and then blood is then pumped to the lungs where the blood becomes filled with oxygen and then pumped back to the left side where it is then pumped back out by way of the left ventricle.
Blood is made up of four key elements. Red blood cells, white blood cells, platelets, and plasma. Red blood cells transport oxygen to cells around the body and have a large surface area to maximise the amount of oxygen they can carry. White blood cells fight infection and make antibodies to surround and overcome bacteria. Platelets are responsible for clotting. Plasma contains, amongst other things, substances dissolved during the process of digestion.
Blood is transported through three main types of vessels. Arteries carry oxygenated blood away from the heart to various parts of the body. Veins transport deoxygenated blood back from its various destinations to the heart. Arteries have no pulse as there is no pump to push the blood through the venal systems. They also have to fight gravity and cope with lower pressure and thinner walls. To achieve their mission they are aided by a series of muscular contractions and valves, which prevent blood falling due to gravity. Finally, capillaries are minute bood vessels that join onto arterioles. They are one cell thick and cross into tissue cells (e.g. musculature) and are the exchange points for nutrients (oxygen and glucose) which help to poser the body.
Muscles move and make us capable of action by virtue of contractions and extensions. Muscles are attached to bone by tendons and exert force by converting chemical energy into tensions and contractions. They are made up of tiny protein filaments that work together to produce motion. There are three types of muscles: cardiac muscles, smooth muscles and skeletal muscles. The first two are found in the heart and other internal organs. They are involuntary muscles as they are not consciously controlled. Skeletal muscles are the most abundant tissue and carry out voluntary movements. They are responsible for 23% of a woman’s weight, and 40% of a man’s weight.
There are four physical properties of skeletal muscle. Excitability is the ability to respond to stimulation from the nervous system. Contractibility is the ability to shorten and contract., thus providing tension. Extensibility is the ability to increase in length – can you touch your toes?! Elasticity is the ability to return to resting length and shape after stretching. Muscles work concentrically (shorten), eccentrically (lengthen), or isometrically (contraction to create stability). The energy to produce these tasks comes from fats, carbohydrates, and proteins fed through arteries via capillaries in plasma.
Aerobic energy production happens using oxygen. Any effort of sufficiently low intensity that respiration can fully supply the requisite energy levels is done aerobically. Endurance work is aerobic in nature. It is linked to recovery time. Box to box midfielders and wingers are archetypal of players who need good stamina and recovery from sprints: In reality though all players need to be good at this. Anaerobic energy production occurs when the oxygen transported is not enough to supply all the energy demands of the situation. Short bursts of high energy activity will be produced this way e.g. jumping, turning and accelerating. When recovery time is low, strong anaerobic ability is required.
Response to exercise
Reactions to exercise can all be seen as a way of ensuring maximum efficiency in generating energy supplies for the activity undertaken. Faster beating of the heart mean more blood is pumped round the body and so more energy supplies in the plasma and oxygen in the red blood cells can reach the muscles. Faster breathing ensures more oxygen is taken into the lungs. Sweating ensures the body remains at a temperature at which it can best function. Some of the heat given off during exercise is useful as muscles work best at 38.5 degrees, 1-2 degrees warmer than the rest of our bodies. Heavy legs are associated with a build up of lactic acid. This occurs when not enough oxygen can reach the muscles. This can lead to muscle failure.
Physical exertion of a footballer (non position specific)
Short sprints (50m)
Slow jogging
Walking
Running backwards, sideways and diagonally.
Accelerating and defending.
Jumping
Tackling
Kicking
Changing direction/turning – happens 400+ times over more than 90 degrees in a game.
Contesting possession
Fast recovery
Whilst these things are important to practice with the ball, only 2-3 minutes is spent with the ball in any one game. So some key, intense work should be done without the ball. Think about how these things can also be developed with the ball, as this work is more fun.
