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Acute Exercise - How The Body Responds

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Zoe Dickins

on 5 February 2014

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Transcript of Acute Exercise - How The Body Responds

How The Body Responds To Acute Exercise Zoë Dickins 12CTR SS2 Energy Systems Acute Exercise The Musculoskeletal Response The musculoskeletal system allows and enables the body to move through a system of muscles, bones, tendons, cartilage and ligaments.
Each part of the system is operated by the nervous system, which has its main control centre in the brain, this creates voluntary movement such as kicking a ball.
The body moves through different muscle contractions, these contractions are initiated by the nervous system. Every muscle has an insertion in a bone, therefore when the muscle contracts the bone is pulled towards the contracting muscle.
The skeletal system provides structure for the body, whereas the muscular system facilitates movement, helps to maintain posture, and can also produce heat through contracting. All organisms require energy. Including the human body, which requires energy to move. Energy can be generated in different ways depending on the duration and the intensity of the activity being performed.

Activities that consist of long endurance require the body to produce energy at a slow rate over a long period of time. For example, endurance cycling.

Activities that consist of short bursts of effort require the body to produce energy at a high rate over a short period of time. For example, sprinting. Increased Blood Supply Increased blood supply occurs due to the increase in demand for oxygen and an increase in metabolic activity when exercising.
Increased blood supply will deliver greater amounts of oxygen as the heart pumps blood quicker around the body, as well as capillary dilation which allows more blood to flow through the capillaries. Cardiovascular Response Increased Muscle Pliability Pliability - this relates to the stretchiness of your muscles and connective tissue. Increased Range of Movement Changes within joints occur during exercise. Synovial fluid is secreted as a result of joint movement. During exercise the synovial fluid becomes less viscous and therefore the range of movement at the joint will increase.

Viscous - the measure of resistance (thickness) of a fluid.

Most exercises increase your range of motion because they stretch out your muscles. As you carry out the exercise, the muscles will begin to extend more which will allow the joints to be able to move further. Acute exercise lasts for the length of a training session.
During this time our bodies respond to the exercise and physical stress of the physical activity in lots of different ways.
These are called acute responses.

Acute responses - immediate responses to exercise, such as an increase in body temperature and heart rate. Muscle Fibre Micro Tears Tiny tears occur in muscles when they are put under pressure whilst exercising.
These micro tears in the muscle tissue cause swelling, which puts pressure on the nerve endings which results in pain.
To strengthen muscles you can use specific training, however the body must rest to repair the micro tears and refuel before training. Phosphocreatine System The phosphocreatine system is the immediate energy system and is used when the activity is of high intensity or instantaneous. Oxygen is usually not used in this system; the energy used is found in the muscles and the liver. Creatine phosphate has a high energy bond. When this bond is broken, energy is released, this energy is used to resynthesise ATP from ADP. The energy released in this system can almost immediately be replaced. Therefore several short bursts of activity can be repeated without the body becoming fatigued. Lactic Acid System This is a short-term energy system that is used when energy is required for a long period of time at high intensity. However, as the process occurs without oxygen it is not sustainable over a long duration.
Maximal work = 60-90 seconds.
This energy system works by converting the pyruvate produced from the glycolysis of glucose, into lactate, converted by the enzyme Lactate Dehydrogenase.
The ATP generated allows exercise of higher intensity to continue up in the human muscle, to the point that the lactate reaches toxic levels, at which point the muscle will start to fatigue. Aerobic System The aerobic energy system is a long-term energy system which requires oxygen. This system occurs in the mitochondria of the cells, which convert food into energy. Glycolysis, the link reaction, the Krebs cycle and the electron transport chain make up the metabolic reactions called aerobic respiration. They can only occur when oxygen is present.
Despite producing large amounts of ATP, it takes a long time for the aerobic energy system to do this. Which may be seen as a disadvantage.
It takes a few minutes for the heart to deliver oxygenated blood to the working muscles, therefore the aerobic system is slower to engage in comparison to the other energy systems. Energy System Equations Creatine Phosphate:
ADP + creatine phosphate ATP + creatine

Lactic Acid:
Glucose 2ATP + 2 lactic acid + heat
Glycogen 3ATP + 2 lactic acid + heat

Glucose + oxygen 38 ATP + carbon dioxide + water + heat
Fatty acids + oxygen 129 ATP + carbon dioxide + water + heat Energy Continuum Energy is obtained through food, particularly carbohydrates and fats. This energy is transferred from the food into the contractile proteins in the muscles. The ability for the body to do this will determine the capacity at which the body is able to exercise at different intensities.
ATP is the energy currency of cells and is the continuous supply of energy for the body.
Adenosine Triphosphate (ATP) - a molecule that stores and releases chemical energy for use in body cells.
ATP is a phosphorylated nucleotide and when it is hydrolysed energy is released. When a bond is made between ADP and another phosphate, energy is stored which can then be used at a later stage. Energy Requirements for Different Activities All three energy systems are operational at any one time, however depending on the intensity and the duration of the activity, different energy systems will be the primary provider. Sport ATP-PCr Lactic Aerobic Archery
Track & Field Distance
Track & Field Jumping
Track & Field Sprinting
Track & Field Throwing High

High Low

High When exercising the muscles require a constant supply of oxygen and nutrients, as well as needing the CO2 they produce to be taken away. It is the hearts job to reach these demands.To meet the demands of the exercising muscles, the heart has to pump harder and faster as more oxygen is required.
If this is repeated regularly, then over time the heart will become stronger,
as with any muscle that is exercised frequently. Respiratory Response Breathing is controlled by a respiratory centre found within the medulla oblongata. The centre is sensitive to pH levels in the blood and reciees information via chemoreceptors around the body which detect the change in pH levels. The change in pH indicates a change in carbon dioxide concentration.

During acute exercise the changes to the respiratory system include:

•Increased ventilation (provided by an increased tidal volume and increased respiratory rate)

•Increased diffusion of oxygen and carbon dioxide at the alveolar-capillary interface due to increased surface area and increased concentration gradients of oxygen and carbon dioxide Heart Rate Anticipatory Response Before exercise, your heart rate usually picks up as a result of the anticipatory heart-rate response. When we think about exercise before we actually start exercising, the nerves that release the chemicals that adjust your heart rate increase the heart rate.
This is because the body anticipates exercise and therefore prepares for the activity, increasing the amount of oxygen being delivered to the muscles so that they have an adequate supply of oxygen for when they begin exercising. The rate that the heart reaches before the start of exercise is called the anticipatory heart rate. Activity Response Activity response is similar to that of the heart rate anticipatory response. At the start of exercise, the nerves in the brain (in the medulla) detect cardiovascular activity. The nerves then send out chemical signals to increase the heart rate, as well as the strength at which the heart is pumping. This means that more blood, which carries oxygen, is delivered to the exercising muscles at a faster rate.
Regional blood flow is also altered to meet the correct proportions against the intensity of the activity being carried out. This means that some areas will have a higher blood flow if they are exercising such as the biceps, in comparison to areas that are not exercising and therefore require less blood such as the liver. Here is a quick video to summarize how acute exercise effects the body. Increased Blood Pressure Blood pressure = the pressure of blood against the walls of the arteries.
There are two different types of blood pressure; systolic and diastolic. During exercise both the heart rate and the blood pressure increase, however there are mechanisms that prevent the blood pressure becoming too high, and also bring it down.
Both oxygen consumption and heart rate increase during aerobic exercise to reach the demands of the intensity of the activity. This means that the pulse rate will rise and the blood flow to the muscles increases. Systolic and Diastolic Pressure Systolic blood pressure - the highest pressure within the bloodstream, which occurs during each beat when the heart is in systole (contracting).

Diastolic blood pressure - the lowest pressure within the bloodstream, which occurs between beats when the heart is in diastole (relaxed - filling with blood).

Blood pressure increases during exercise because heart rate increases. If the increase is excessively high, the systolic pressure it will exceed 250mm Hg or the diastolic pressure may exceed 90mm Hg.
If someone has a high resting blood pressure, when they exercise they will again have a high pressure, which is usually higher than that of others exercising.
Blood pressure produces the largest response when someone is performing high-intensity weight lifting. Vasodilation Vasoconstriction Vasodilation - when blood vessels widen in an attempt to increase blood flow. Vasoconstriction - when blood vessles narrow and reduce blood flow. Increased Breathing Rate Increased Tidal Volume Thermoregulation is regulating body temperature; the cardiovascular system plays a role in thermoregulation. If the body temperature becomes too high, blood vessels just under the surface of the skin dilate which means that they increase in size. This is called vasodilation.
Due to the increase in surface area, more heat can be transferred across the skin and out into the air, the loss of heat therefore cools the body down. On the other hand, if body temperature becomes too low, the vessels constrict which means that they decrease in size. This is called vasoconstriction. This means that less heat will be lost through transfer across the skin and into the air as there is a smaller surface area; therefore more heat remains in the body. Tidal volume is the amount air inhaled and exhaled with each breath. This is usually around 500cm cubed.
Tidal volume increases to around 3-4 litres during exercise.
This increase occurs as the breathing rate Pulmonary ventilation increases during exercise, which increases both the depth and rate of breathing. This is regulated by;
The inspiratory centre, which increases the stimulation of the diaphragm and external intercostal muscles. It also stimulates the other muscles used during inspiration, such as the pectoralis minor and sternocleidomastoid. This increases the force of contraction and therefore increases the depth of inspiration.
The expiratory centre stimulates the expiratory muscles, which are the internal intercostal muscles, obliques and rectus abdominus. This causes a forced expiration which reduces the duration of insiration.
In response to this, the inspiratory centre immediately stimulates the inspiratory muscles, causing them to inspire. The results in the intensity of the exercise increasing, the depth of breathing decreases and the rate of breathing increases. Muscles become more pliable when they become warm, this helps to reduce the risk of injury.
This is because, during exercise the muscles contract quickly. These fast contractions generate heat, which makes the muscles more pliable.
e.g. when you continuously stretch an elastic band, it generates heat. Therefore, the warmer it is the further you can stretch it each time without it snapping. increases to try and meet the oxygen demand for the respiring muscles. Increasing the tidal volume allows a greater intake of oxygen and exhale of carbon dioxide which is produced by the respiring muscles. Bibliography OCR PE AS Heinemann Textbook
BTEC Sport Level 3 National Diploma Pearson Book 1
OCR Biology AS Heinemann Textbook
http://www.youtube.com/ watch?v=FyhYHlA7bZw
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