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, and then 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 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: ATP is a molecule in the body that is used to break down energy. There are two main energy systems Aerobic and anaerobic. When energy is needed, ATP is broken down into ADP (Adenosine Diphosphate). This process breaks the high energy Phosphate and so releases energy for use in the body.
The body must be able to adopt to the change in physical activity. The first system that we use is the ATP-PC system. This produces Phosphocreatine which is only used for short durations of up to 10 seconds. The system neither uses oxygen nor produces lactic acid and is thus said to be alactic anaerobic. This system is used for very short, powerful movements like a golf swing or a 100m sprint. Once all the energy production from the breakdown of ATP has been used we have a potential problem. We therefore require stores to be eplaced in the form of an endothermic reaction, to resynthesise ATP. Once our CP stores are depleted the body resorts to stored glucose for ATP.
The breakdown of glucose or glycogen in Lactic Acid system results in the production of lactate and hydrogen ions. The accumulation of hydrogen ions is the limiting factor causing fatigue in runs of 300 metres to 800 metres. After the entire PC is used up the body goes into the aerobic energy system. This system utilises proteins, fats and carbohydrate (glycogen) for the resynthesising ATP. Cardiovascular Response:
Before we start to exercise our heart rate increases slightly in anticipation of the activity ahead. It is mediated through the releases of neurotransmitters called epinephrine and norepinephrine also known as adrenaline and noradrenaline. This is known as the Anticipatory rate. After the initial response our heart rate increases in direct proportion to the exercise intensity until a maximum is reached. Systolic BP increases in direct proportion to increased exercise intensity. Diastolic BP changes little, if at all, during endurance exercise, regardless of intensity.
Vasoconstriction and vasodilatation occur as the oxygenated blood needs to be diverted to the working muscles and reduce blood flow to less important systems e. g. Digestive System. Respiratory Response: When you are exercising your respiratory system responses 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 increase as a response to exercise this is because the muscle needs an increase of oxygen. 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.
Long Term Responses Cardiovascular System: The hearts mass and volume increases and cardiac muscle undergoes hypertrophy. It is the left ventricle that adapts to the greatest extent. As well as the chamber size increasing as a result of endurance training. A person’s stroke volume will also increase as an increase in blood plasma and blood volume occur and reduced heart rate which increases the diastolic filling time. This increased filling on the left ventricle increases its elastic recoil thus producing a more forceful contraction. So not only is the heart filled with more blood to eject, it expels a greater percentage of the end-diastolic volume.
A persons venous return increases due to the higher cardiac output. Capillarisation occurs. This is the increased amount of capillaries over the muscles which mean more blood flows which will give you more oxygen, and nutrients so you will be able to participate in the exercise longer. There will be more capillaries present so the quicker the oxygen will get to the muscles. A decrease in the persons resting heart rate means they are able to recover quicker after an activity. Arterial walls will become more elastic which allows greater tolerance of changes in blood pressure.
Muscular system: Our muscle Hypertrophy increases which means our tendons and ligaments need to also become stronger to cope with the additional stresses and impact put through them. The amount of Myglobin within skeletal muscle will also increase, which will allow more Oxygen to be stored within the muscle, and transported to the mitochondria. With more oxygen being sent to the Mitochondria they also have to increase. This means with increased numbers of mitochondria there will be an increase in the rate of energy production. The muscles will also be capable of storing a larger amount of glycogen for energy.
Enzymes involved in energy production become more concentrated and efficient to aid the speed of metabolism. Skeletal System: There will be an increase in the production of Synovial fluid which means that our joints will be more lubricated to reduce the risk of injury and will allow a greater range of movement. The Hyaline cartilage will increase making the joints stronger and its high elasticity will increase which helps to cushion and protect bones. An increase stretch in ligaments allows for a better range of movement and less chance of an injury occurring as it allows the ligaments to come under more strain.
Long term exercise will increase osteoblastic activity this means transporting more calcium from your blood to your bones. This will increase the density and strength of your bones. Respiratory System: The respiratory muscles such as the Diaphragm and the Intercostal muscles will increase in strength. This will result in larger respiratory volumes, which will allow more Oxygen to be diffused into the blood flow. There will also be an increase in the number and diameter of capillaries surrounding the alveoli which leads to an increase in the efficiency of gaseous exchange.
Energy System: Long-term exercise will enhance all 3 of the energy systems in the body. A person’s recovery will improve as they will be able to recover quicker between each activity. There are multiple responses, one is if lactic acid build up in the muscle’s you will feel a burning pain, another is that when you exercise the muscles get micro tears and the body will register that as soreness or pain, and the body will heal and repair the tears and then it will add a little more muscle, it does this to compensate so that next time you lift that weight you can do it easier and with less effort.
Also when you do any activity the neurons in the brain will develop more connections with other brain cells called “synapses”, and when they do this the task becomes easier because your brain become accustomed to it and with some activities you will get to the point where you can do it without paying much attention.