The effect of acute exercise on the Musculoskeletal, Energy, Cardiovascular and Respiratory Systems Andrew White
There is an increase in blood supply as your body is working overtime. The blood supply has to increase because it has to go to the parts in your body which you are exercising the most e.g. If you are taking a run, the blood supply will increase because your legs will need more energy, therefore there will be more blood circulating your legs than normal because you are overworking them. Your muscles and all your body organs need more energy and oxygen; this is because your body is working more than usual. Your body needs to do many things such as sweat, which helps you cool down, and to get energy to all of your cells in your body to help you carry on exercising, if your body didn’t do this, you wouldn’t be able to carry on exercising.
During acute exercise your muscle pliability increases which allows a greater range of movement which helps reduce injury. Acute exercise will cause muscle fibre micro tears. This is generally known as micro-trauma. The myosin heads and the actin filaments will be pulled from the myofibrils. This damage will cause a release of chemicals that cause the soreness after your period of exercise. The chemicals released also stimulate repair and growth in the area to rebuild the tears in the muscle.
Energy systems response to acute exercise happens when the exercise is a high intensity, which is too much for the cardiovascular and respiratory system to deal with. The first response is to use the creatine phosphate energy system. This works in the fast-twitch muscle fibre of the muscles high energy creatine phosphate compounds which are able to break down extremely quickly to create large amounts of ATP. ATP is where we get the energy from to continue and this system only works for the first 10 to 20 seconds of exercise with 100% effort.
It is likely that the lactic acid system would provide energy at the start of any activity, even if the intensity is not enough for the aerobic system. If you go out on a jog, most of this is powered by the aerobic system, but the start of the jog it needs to create ATP so that the heart and lungs have enough oxygen and can saturate the blood before the aerobic system can kick in. When the heart and lungs have caught up with the movement of the activity and the intensity is low enough, then the aerobic energy system can fuel the body.
The Energy Continuum
The energy systems all work together to produce energy; however, what we are doing determines which energy system supplies the majority of the ATP. The energy continuum highlights which energy systems are producing the most amount of energy at different stages of an activity. At rest, nearly all of our energy is provided by the aerobic energy system; then, if we suddenly start to exercise, we need more ATP than the aerobic energy system can supply, so the phosphocreatine and lactic acid energy systems supply the ATP.
In some sport , the energy supply comes from all three energy systems at different points – for example, in football, when you are jogging slowly, the aerobic energy is used; for a short sprint to get to the ball, the phosphocreatine system is used; then running back down the pitch and running quickly to defend will mainly use the lactic acid energy system. Cardiovascular System
Your heart rate will begin to rise before you even start to exercise. Your brain realizes you are going to work out and releases adrenaline to speed up your heart in preparation for the upcoming exertion. This is called the anticipatory response. The heart rate will continue to rise in direct proportion to the intensity of exercise until maximum heart rate is achieved. Activity Response
At the start or just before the exercise, nerve centres in your brain detect cardiovascular activity. This results in adjustments that increase the rate and pumping strength of your heart. At the same time the regional blood flow is altered in proportion to the intensity of the activity undertaken. Vasodilation and Vasoconstriction during Exercise
Vasoconstriction occurs before exercise when the blood flow in the body is at a normal rate or when the body needs to supply specific areas of the body with more blood than others, for example in the 100m sprint the majority of the blood will be pumped to the legs, so other blood vessels will contract restricting blood flow to unused organs and muscles. Vasodilation occurs during exercise when the body needs to release heat through the skin and to get more blood to the organs and muscles that require the most blood during specific exercise. This is done to get more oxygen to the muscles, but to also get rid of more carbon dioxide. Respiratory System
When you are exercising your respiratory system responds by your breathing rate increases and you start to breathe heavily, this happens because your muscles need more oxygen so you breathe deep and quicker so a supply of oxygen can get to the muscles, also when you finish exercise your breathing rate will decrease and start to recover. Another response from the respiratory system is the tidal volume, which increases as a response to exercise this is because the muscle needs an increase of oxygen. Exercise causes an increase in tidal volume because your requirements for oxygen go up.
This increase is measured in different ways depending on when it occurs during your exercise. An increase in tidal volume is necessary to effectively meet your body’s increased oxygen requirements, as an increase in your rate of respiration alone is not sufficient. As well as the breathing rate and tidal volume, the pulmonary ventilation is also a response to exercise on the respiratory system. The pulmonary ventilation increases when the body starts to do exercise, this happens because like most of the other responses the muscles need more oxygen, there is also an increase in the removal of carbon dioxide.
There are two neural mechanisms that control respiration, one for voluntary breathing and one for involuntary breathing. The voluntary impulse originates in the cerebral cortex region of the brain and the automatic impulse originates in the medulla oblongata. There are chemoreceptors in the brain and the heart that sense the amount of oxygen, carbon dioxide and acid present in the body. As a result, they control the respiratory rate to compensate for any disruptions in the balance of any of these chemicals. Too much carbon dioxide or acidity and too little oxygen cause the respiratory rate to increase and vice versa.
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