Unit 2 task 1 – Know the body’s response to acute exercise
Grading criteria – P1, M1
Musculoskeletal response to exercise
Your skeletal system responds to acute exercise just like your muscles. High intensity physical activity can reduce the risk of bone loss. Regular exercise may provide long-term benefits, especially for skeletal systems in children and young adults. http://www.livestrong.com/article/359456-your-skeletal-systems-response-to-exercise/ Your skeletal system responds to exercise by taking in more calcium. Osteoblasts are cells that bring calcium into bones, they slow down and transport less calcium from your blood to your bones during inactivity, but when exercising it has the opposite effect and increases osteoblastic activity. Exercise that require force through a particular bone strengthens that bone. Myoglobin releases its stored oxygen to use in aerobic respiration. During exercise oxygen is diffused into the muscles from the capillaries more quickly due to the decreased oxygen concentration in the muscles. Exercise helps you increase the density and strength of your bones this enables us to maintain muscle strength, coordination, and balance, which helps to prevent falls and related fractures later in life.
Muscles and tendons becomes more pliable when they are warm, this helps reduce the risk of injury, and this is because during acute exercise the muscles contract quicker. These fast muscle contractions generate heat, which makes the muscles more pliable this increases the range of movements in your joints. 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. Most exercise increases your range of movements because they stretch out your muscles. As you’re exercising, the muscles will being to extend more which will allow the joints to be able to move further.
Muscle fibre 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 they must rest to repair the micro tears and refuel before training. Recovery time for muscle fibre tears depends on the severity of the tear. For example, if you over strain your hamstrings, tiny tears will occur, it can take up to 12-21 days to recover however more sever tears like completely rupturing the muscle fibres, recovery can take up to 3-4 months. https://prezi.com/9fd02umydn1u/acute-exercise-how-the-body-responds/ Reaction to excersise – Energy systems
All types of exercise require energy but the amount needed depends on the intensity and duration of the exercise. Energy comes from a few things; our diet, carbohydrates and also comes from the oxygen we breathe in. when we breathe air, it enters our blood through the alveoli in our lungs and is absorbed by the haemoglobin in our blood which our heart then pumps around our body into the cells in our muscles.
Phosphocreatine
In order for the third phosphate molecule to be resynthesized back on to ADP to make ATP, the phosphocreatine energy system uses a substance called creatine phosphate. It is a very quick source of energy and therefore can only be used over a short period of time for high intensity exercises. Once the energy has been depleted and the store of energy has been emptied, it takes a certain period of time before the energy will replenish. The phosphocreatine energy system functions anaerobically and therefore is used when oxygen is unavailable. Sports such as 100m sprinters require a burst of energy for a short period of time. This is why it is advised that the performers wait and rest an average time of around 3 minutes between each lift. This is to allow the phosphocreatine stores to resynthesize in order for the performer to have the short burst energy ready.
Lactic Acid Energy system
The lactic acid energy system is also sometimes referred as a short-termed energy system. ATP can be made via the breakdown of glucose and glycogen stores. This particular process is known as an anaerobic process as it does not require any oxygen. It is important to note that this process is unsustainable for long durations of time. Approximately 60 – 90 seconds of maximal output from the body is possible whilst using this particular system. This energy system is typically used by performers in events such as the 800 and 400m (running). This system breaks down liver and muscle glycogen stores without requiring the presence of oxygen. As a result, lactic acid is produced. As this system can provide maximum energy for 60-90 seconds these events really push it to the boundaries and gets the most energy possible from the available stores. This energy system is also used in various team sports such as netball, football and basketball. This system can be recovered when oxygen is coming into the body, this is because the oxygen has the ability to convert the lactic acid into carbon dioxide. After around 60 seconds the energy store is empty and the body will begin to experience fatigue. This system produces lactic acid which defuses in to the blood and muscles. However if it does not diffuse, it builds up and causes discomfort in the muscles which will not allow the muscles to contract and causes cramps.
Aerobic Energy system
The aerobic energy system is a long term system that requires oxygen. This system happens in the mitochondria of the cells which convert food into energy. The link reaction, kerb cycle, glycolysis and the electron transport chain make up the metabolic reactions which is called aerobic respiration. This can only happen when oxygen is present. Even though it produces large amounts of ATP, it takes a long time for the system to do so. This is seen as a disadvantage. It takes a few minutes for the heart to deliver oxygenated blood to the active muscles this is why the aerobic system is slower to engage compared to the other energy system. A sporting example of this would be a long distance runner. During a long distance run, your body undergo a low intensity but long durational activity. During long distance runs, the ATP energy system are used at the start of a race but then it goes through to the aerobic system. https://prezi.com/4ebmy_usimci/the-acute-effects-of-exercise/
Energy continuum
The body's capacity to exercise for a variety of intensities and durations is directly determined by its ability to take as much energy as possible from food and then transfer it to the contractile proteins within the muscles. This transfer process is responsible for the energy that is only enabled due to the many of complex chemical reactions that occur. It is imperative that the body is able to maintain a continual supply of energy, which is achieved through use of adenosine triphosphate also known as ATP. Adenosine triphosphate is formed in a reaction between an ADP molecule, also known as adenosine diphosphate and phosphate. It is used to carry energy in cells and is made up of a base known as adenine, combined with three phosphate groups. https://prezi.com/4ebmy_usimci/the-acute-effects-of-exercise/
Energy requirements of different sport and exercises activities
The body is unable to switch between one energy system to another which therefore means all three different energy systems are functioning at any given time, however the different energy systems vary as to which one is the primary energy supplier depending on the duration and intensity of the activity being participated in. For example the primary energy system used within sports such as basketball and archery is the creatine phosphate energy system as the activity being participated in only require short bursts of energy. Sports such as football also call upon the use of the creatine phosphate energy system for short bursts of energy, however it is also necessary for the aerobic energy system to be in use as the participant is required to run for an extended period of time. http://www.ptdirect.com/training-design/anatomy-and-physiology/adaptations-to-exercise/acute-respiratory-responses Cardiovascular response to exercise The cardiovascular system consists of the heart and the blood vessels through which the heart pumps blood around the body. During acute exercise, a number of changes take place to the cardiovascular system to ensure that the muscles receive the required amounts of oxygen and nutrients. During exercise, the heart rate needs to be increased in order to ensure that the working muscles receive adequate amounts of nutrients and oxygen, and that waste products are removed. Before you even start exercising there is an increase in your heart rate, called the ‘anticipatory rise’, which occurs because when you think about exercising it stimulates the sympathetic nervous system to release adrenaline. Activity response is similar to the anticipatory response, this causes blood pressure to rise and stroke volume to increase because of the increase in the amount of blood your heart pumps out. As the start of exercise, the nerves in the brain senses cardiovascular activity. The nerves then send out chemical signals to increase the heart rate, as well as strength at which the heart is contracting. This means that more blood, which carries oxygen, is delivered to the exercising muscles at faster rate. Blood oxygen transport during acute exercise reduces the amount of plasma that is being made hence the haemoglobin concentration increases allowing more oxygen to be carried by the blood cells to the working body parts.
During acute exercise, your body has an increased need for oxygen. The active muscles need more oxygen to perform, therefore your heart and cardiovascular system responds by pumping out more oxygenated blood to your muscles. To take in oxygen and get rid of waste, your respiratory system must also make adjustments to help meet the demands of the body during acute exercise. During acute exercise, your adrenal gland increases production of adrenaline that directly affect the heart and the ability to transport oxygen and carbon dioxide throughout the body. The hormones then directly assist the sympathetic nerves to stimulate the heart to beat stronger for increased stroke volume and faster for increased heart rate and an overall increase in cardiac output. The increasing oxygen demands from the working muscles must be transported through the blood vessels. During exercise, the sympathetic nerve stimulates the veins to constrict to return more blood to the heart. This blood is carrying carbon dioxide from the muscles and can increase the total stroke volume of the heart by 30 to 40 percent.
Chemoreceptors (chemical-sensing cells) in the cardiovascular system monitor chemical characteristics of the blood to help regulate function of both cardiovascular and respiratory systems. The PH of blood when at rest has a PH of 7 which is classed as neutral. During acute training, lactate levels increase in the blood. At the point known as the anaerobic or lactate threshold, lactate is produced more quickly than it can be removed or metabolised. This results in a build-up of hydrogen ions within the muscle, causing the muscle to become increasingly acidic, thus, the muscles feeling fatigued during exercise.
Baroreceptors provide information essential to the regulation of autonomic activities by monitoring changes in pressure. They sense blood pressure and then send signals to the heart, the arteries, the veins, and the kidneys that cause them to make changes that regulate blood pressure. These sensors are found in the large arteries closest to the heart. The brain is the command centre for the body, especially during times of exercises. Mechanisms throughout your body are set up to give feedback to the brain so that adjustments can be made through the autonomic nervous systems. Baroreceptors respond and adapt to exercise training.

Blood pressure is the amount of blood pressured against the walls of your arteries. During acute exercise, oxygen consumption and heart rate increase in relation to the intensity of the activity chosen to do this is because the muscles require more oxygenated blood from the heart during exercise. Systolic blood pressure rises progressively while diastolic stays the same or lowers slightly. This causes pulse rate rises and the blood flow to the muscles increases. Blood flow is shunted from the non-essential organs of the body to the working muscles when exercising and cardiac output increases. The blood flow to the lungs increases due to the increased activity of the right ventricle which pumps blood to the lungs. As a greater quantity of blood gets pumped from the heart, the pressure rises in the blood vessels that transport the blood with each heartbeat.

The sympathetic nervous system cause heart rate to increase and blood vessels to constrict during acute exercise. Sympathetic nerves also has major role in redistributing blood from one area of the body to another. The smooth muscle layer of the blood vessels is controlled by the sympathetic nervous system and stays in a state of slight contraction known as vasomotor tone. By increasing sympathetic stimulation, vasoconstriction occurs and blood flow is shunted from the major organs and redistributed specifically to the muscles to help them work more efficiently. When stimulation by sympathetic nerves decreases, vasodilation is allowed which will increase blood flow to that body part. Blood pressure rises to facilitate the body’s increased flow of blood. Reflexes speed up and muscles tense. This allows blood to carry oxygen more efficiently to the muscles and move waste away from muscles.
During exercise, your muscles need oxygen to break down fats and carbohydrates for energy. To make room for fresh oxygen, the muscles releases by-products such as adenosine and carbon dioxide, which prompt the blood vessels in that area to dilate or expand, this process called vasodilation. This vasodilation allows more oxygenated blood to be delivered to the muscles.

Respiratory system to exercise
The human respiratory system is a series of organs responsible for taking in oxygen and expelling carbon dioxide. The primary organs of the respiratory system are lungs, which carry out this exchange of gases as we breathe.
Tidal volume is the volume of air you breathe in a single breath. During acute exercise, there is an increase in tidal volume because the requirements for oxygen rise. This increase is mediated in different ways depending on when it occurs during exercise. An increase in tidal volume is required to effectively meet the bodies increased oxygen requirements, as an increase in your rate of respiration alone is not sufficient. The blood flow to the lungs increases by about 4-5 times from that of its resting state. Your body does this by increasing the rate of your heartbeat and the amount of blood that comes through the heart and goes out to the rest of the body. The rate of blood pumped by the heart is a product of the rate at which the heart beats and the volume of blood that the heart ejects with each beat.
When you adjust from a resting state to exercising, your rate of respiration, or the number of breaths you take per minute, immediately responds. Initially, your respiration rate increases rapidly. After that initial response, or first few minutes, your respiration rate will level off. However, if you increase you’re the intensity, your respiration rate will increase, but not as rapidly as the initial response. If the exercise is intense, breathing rates can increase from an average resting rate of 15 breaths per minute up to 40 – 50 breaths per minute. The environment in which you are exercising in has an effect on how many times you breathe in a minute. If the environment is hot and humid, it slows down heat loss, and can increase internal body temperature. In order to fight that, your respiration rate will also increase. There is also an increase in the rate of gas exchange at the alveoli and capillaries. This is attributed to the dilation of blood vessels and the surface area of the air sacs within the lungs.
Your breathing rate is regulated by neural and chemical mechanisms. Respiration is controlled from the brain to nerves that supply respiratory muscles. The primary respiratory muscle is the diaphragm, which is supplied by the phrenic nerve. The rate at which the nerves discharge is influenced by the concentration of oxygen, carbon dioxide and the acidity of the blood. There are chemoreceptors in the brain and the heart that sense the amount of oxygen, carbon dioxide and acid present in the body. So, they regulate the respiratory rate to take care for any disruptions in balance of chemicals. Too much carbon dioxide or acidity and too little oxygen cause the respiratory rate to increase. Carbon dioxide chemoreceptors are much more sensitive than oxygen chemoreceptors.
The intercostal muscles support the increase in respiration during acute exercise. Without these muscles, your lungs would not be able to increase the air flow required for physical activity. The intercostal muscles come in two different types; both are located around the ribcage. The internal intercostal muscles are located on the inside of the ribcage. The external intercostal muscles lie on the outside of the ribcage and extend from the back of the ribcage to the front. During acute exercise, your respiratory rate increases, which is facilitated by the intercostal muscles. During rest, the external intercostal muscles work to pull air into the lungs. During acute exercise, the act of exhaling becomes an active movement. The internal intercostal muscles work to force air out of your lungs by moving the ribcage down and in, therefore forcing air out. Some muscles located in the neck can also contribute to the work of breathing during exercise. The sternocleidomastoid muscle, which runs from the back base of your skull down to your chest, may be called to support breathing during periods of strenuous exercise. This muscle acts to pull your rib cage upward, supporting lung expansion and gas exchange.

During inspiration, air is forced into the lungs because of the expansion of the thoracic cavity. Expansion of the thoracic cavity is caused by the contraction of the diaphragm at the bottom of the rib cage and the contraction of the external intercostal muscles, causing the ribs to move upwards and outwards. During exercise, the body's need for oxygen increases dramatically and ventilation rate is increased, therefore, the depth of breathing also increases during exercise due to the anatomical dead space, which is the air in the nose, mouth, larynx, tracheas, bronchi and bronchioles. This air reaches the alveoli first during inspiration. During expiration, the most important muscles are those of the abdominal wall, which drive intra-abdominal pressure up when they contract, and thus push up the diaphragm, raising pleural pressure, which raises alveolar pressure, which in turn drives air out. The internal intercostal muscle assist with active expiration by pulling the ribs down and in, thus decreasing thoracic volume.
Baroreceptors are found in blood vessels and they provide information essential to the regulation of autonomic activities by monitoring changes in pressure. The brain is the command centre for the body, especially during times of exercises. Mechanisms throughout your body are set up to give feedback to the brain so that adjustments can be made through the autonomic nervous systems. Baroreceptors respond and adapt to exercise training. Mechanoreceptor cells are found in the lungs. They command the control ventilation in the lungs. During acute exercise, signal gets sent from the respiratory control centre to order the lungs to increase lung capacity and lung volume. The mechanoreceptors found in your skin responds to a change in the external stimulus such as pressure or temperature. For example, hair sticking up from your skin or shivering when you are cold.
Central nervous system
The central nervous system consists of the brain and spinal cord. Its main function is to act as a control system for the body. There are various control centers in the central nervous system that maintain control in the body. They are located in the medulla oblongata which is in the back of your brain. The CNS control the movements, this is done by CNS sending signal to the brain and receiving signals from certain body parts.
Respiratory control system
When the muscles are active they respire more quickly and causes several changes to the blood, such as decreased oxygen concentration, increased carbon dioxide concentration, decreased pH and increased temperature. All of these changes are detected by various receptor cells around the body, but the pH changes are the most sensitive and therefore the most important. The main chemoreceptors are found in the walls of the aorta as they monitor the blood that leaves the heart also they are found in the walls of the carotid arteries which monitors the blood to the head and brain and they are found in the medulla, monitoring the tissue fluid in the brain. The chemoreceptors send nerve impulses to the respiratory control centre indicating that more respiration is taking place, and the respiratory centre responds by increasing the heart rate.
Cardiac control centre
The medulla oblongata control's the CCC which is primarily responsible for regulating the heart. The CCC is controlled by the automatic nervous system meaning it is under involuntary control and would consist of sensory and motor nerves either the sympathetic or parasympathetic nervous system. Neural control stimulates the cardiac control centre during exercise. The Proprioceptors in muscles, tendons and joints inform the CCC that movement activity has increased. The Chemoreceptors senses the chemical level changed within the body (Lactic acid, carbon dioxide) Baroreceptors are sensitive to stretch within the blood vessel walls, in aorta and carotid arteries inform the CCC that blood pressure has increased.
References
www.oxfordunited-yc.co.uk/Energy-System-responses-to-acute-exercise/ http://www.slideshare.net/sihamgritly/6-response-of-the-cardiovascular-system-to-exercise http://www.livestrong.com/article/341117-how-is-your-breathing-rate-controlled/