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Prelim PDHPE Core 2: Body in Motion

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This compulsory module examines the scientific foundations of human movement. In this module, students explore how the body moves and why it moves in particular ways. Students focus on the relationships between anatomy, physiology, fitness, biomechanics and efficient human movement.

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Prelim PDHPE Core 2: Body in Motion

  1. 1. 1) How do the musculoskeletal and cardiorespiratory systems of the body influence and respond to movement? 2) What is the relationship between physical fitness, training and movement efficiency? 3) How do biomechanical principles influence movement?
  2. 2. Tell me what are the four functions of the skeletal system? 1) It Supports the organs and tissues of the body. Without this support they would collapse under their own weight. 2) It provides Protection for internal organs. For example, the cranium protects the brain; the thorax protects the heart and lungs. 3) It provides a base for the attachment of muscles and so allows Movement with the bones acting as levers. 4) The bones are a source of supply of blood cells and a store for minerals required for the body to function. For example, red and white blood cells are produced in the bone marrow, which is found in the middle of bones.
  3. 3. Label the skeletal system ACTIVITY ONE – BONE HUNT Hidden around the classroom are the bones of body – can you find them? ACTIVITY TWO - SKELETAL JIGSAW As a group can you assemble the skeletal system correctly? LABEL THE SKELETON Using the labels provided – How many bones can you correctly name? HOW MANY DID YOU GET RIGHT? Check with Charlie (Classroom skeleton)
  4. 4. What are the main types of bones? 1) Long bones are longer than they are wide, the function as levers. For example… 2) Short bones have a short axis and are found in small spaces such as the wrist. They serve to transfer forces. For example… 3) Flat bones have a broad surface and serve as places of attachment for muscles and to protect vital organs. For example…
  5. 5. What are the main types of bones? 4) Irregular bones do not fall into any category due to their non-uniform shape. Primarily consist of cancellous bone, with a thin outer layer of compact bone. For example… 5) Sesamoid bones usually short and irregular bones, imbedded in a tendon where it passes over a joint which serves to protect the tendon. For example…
  6. 6. When referencing the anatomy, directional terms are used to identify the location of bones. Anatomical position: a reference position where the subject is standing erect, facing front on and with palms facing forward. 1. Superior — towards the head; for example, the chest is superior to the hips 2. Inferior — towards the feet; for example, the foot is inferior to the leg 3. Anterior — towards the front; for example, the breast is on the anterior chest wall 4. Posterior — towards the back; for example, the backbone is posterior to the heart 5. Medial — towards the midline of the body; for example, the big toe is on the medial side of the foot 6. Lateral — towards the side of the body; for example, the little toe is on the lateral side of the foot 7. Proximal — towards the body’s mass; for example, the shoulder is proximal to the elbow 8. Distal — away from the body’s mass; for example, the elbow is distal to the shoulder. Anatomical Reference: Directional Terms
  7. 7. Joints occur where one or more bones meet. Joints can be fixed, such as the rib cage, or they can be more moveable such as in the elbow. Joints are classified according to their degree or movement. Joints may be classified as: - Fibrous or immovable - Cartilaginous or slightly moveable - Synovial or freely moveable Fibrous joints occur where bone ends are joined by strong, short bands or fibrous tissue such as in the skull. This type of joint does not allow any movement to occur. Cartilaginous joints is where the bones are separated by a disc or plate made up of tough fibrous cartilage. For example the joints of the vertebrae or spine are separated by this tissue thus causing limited movement. Synovial joints allow for a range of movement. These include hinge joints (knee and elbow) and ball and socket joints (hip and shoulders). Synovial joints are made possible with the use of tendons, ligaments, cartilage, and synovial fluid.
  8. 8. What Connects these Joints? Ligaments are fibrous bands that connect bones to bones. These maintain stability in the joint. Tendons are tough inelastic cords that attach muscles to bones. These further strengthen the joint and allow the joint to move. Cartilage is a smooth shiny surface on the bones which allows them to glide across each other freely. Synovial Fluid is a lubricant that keeps the joints moist and nourishes the cartilage to enable easy movement Hyaline cartilage while synovial fluid acts as a cushion between articulating surfaces of the bones, they are also covered with a layer of smooth, shiny cartilage that allows bones to move freely over each other. Thicker in leg joints, where there is greater weight bearing
  9. 9. USING THE A3 RESOURCE, SEE HOW MANY OF THE MUSCLES YOU CAN LABEL ON YOUR SHEET
  10. 10. Muscle Relationships Agonist An agonist or prime mover is the muscle causing the major action. There are agonists for all movable joints and usually more than one is involved in a particular joint movement. Antagonist An antagonist is a muscle that must relax and lengthen to allow the agonist to contract, thus helping to control an action. The agonist works as a pair with the antagonist muscle. The two roles are interchangeable depending on the direction of the movement. Stabiliser Stabiliser or fixator muscles act at a joint to stabilise it, giving the muscles a fixed base. The muscle shortens very little during its contraction, causing minimal movement. This permits the action to be carried out correctly and allows other joints to work more effectively. For example, in a dynamic movement such as throwing, while some shoulder muscles serve to propel the object, others act as stabilisers to allow the efficient working of the elbow joint and to reduce the possibility of damage to the joints.
  11. 11. Q: In ‘leg movement’ name the antagonist and the agonist muscle?
  12. 12. Types of muscle contractions When a muscle is stimulated, it contracts. This may happen in a number of ways. There are three principal types of muscle contraction — concentric, eccentric and isometric. Concentric A concentric contraction is the most common type of muscular contraction. During this contraction, the muscle shortens, causing movement at the joint. Examples of concentric contractions are the contraction of the rectus abdominis to raise the trunk during a sit-up, or the biceps contracting to lift a weight.
  13. 13. Types of muscle contractions Eccentric An eccentric contraction occurs when the muscle lengthens while under tension. The action often happens with the assistance of gravity. Examples of eccentric contractions are the rectus abdominis extending to gradually lower the trunk during the downward action of a sit-up, or the biceps muscle fibres lengthening as the weight is returned to its original position
  14. 14. Types of muscle contractions Isometric An isometric contraction occurs when the muscle fibres are activated and develop force, but the muscle length does not change; that is, movement does not occur. Isometric contractions are commonly seen in attempted movements where a resistance cannot be overcome. Examples are a weight-lifter trying to lift a weight that cannot be moved, or a person pushing against a wall. In each case, the effort is being made, but the muscle length does not change because the resistance is too great.
  15. 15. Types of muscle contractions Examples of Isometric
  16. 16. Activity – Complete the table Do for homework – Application Page 145
  17. 17. Activity – Complete the mind map to answer: How does the body’s muscoskeletal system influence and respond to movement? Do for homework – Inquiry Page 145
  18. 18. aA
  19. 19. Respiration is the process by which the body takes oxygen in and removes carbon dioxide Every cell in our body needs a constant supply of oxygen (O2) and food to maintain life and to keep the body operating effectively. Respiration is a process that occurs in practically all living cells. It uses oxygen as a vital ingredient to free energy from food and can be characterised by the following equation: This process is made possible through the respiratory system that facilitates the exchange of gases between the air we breathe and our blood. The respiratory system acts to bring about this essential exchange of gases (CO2 and O2) through breathing; the movement of air in and out of the lungs.
  20. 20. The parts of the respiratory system and their functions 1) Oxygen enters the body through the mouth or nose. Through the nasal cavities the air is warmed, moistened and filtered for any foreign material 2) The pharynx serves as a common passage for air to the trachea. It leads from the nasal cavity to the larynx (voice box), located at the beginning of the trachea 3) Trachea is a hollow tube, strengthened by rings of cartilage. After entering the chest cavity or thorax, the trachea divides into a right and left bronchus (bronchial tube), which lead to the right and left lung. 4) The inner lining of the air passages, produces mucus that catches and holds dirt and germs. It is also covered in microscopic hairs (cilia) that remove dirt, irritants and mucus through steady, rhythmic movements
  21. 21. Lung Function 5) Lungs consist of two bag-like organs, situated on either side of the heart and enclosed in the thoracic cavity by the ribs at the side and sternum at the front, vetebral column at back and diaphragm below. The light, soft lung tissue is compressed and folded like a sponge and is composed of tiny air pockets 6) The right and left bronchi that deliver air to the lungs divide into a number of branches or bronchioles within each lung. These bronchioles branch many times, eventually terminating in clusters of tiny air sacs called alveoli (singular-alveolus). The walls of the alveoli are extremely thin, with a network of capillaries (tiny vessels carrying blood) surrounding each like a string bag. This is where oxygen from the air we breathe is exchanged for carbon dioxide from our bloodstream.
  22. 22. Lung Function Inspiration = breathing in Expiration = breathing out During inspiration Diaphragm contracts and flattens, external intercostal muscles (between ribs) lift ribs outwards and upwards. This movement increases volume in chest cavity and pulls the walls of lungs outwards, which in turn decreases the air pressure within lungs. In response to this, air from outside the body rushes into lungs through air passages. During expiration Diaphragm relaxes and moves upwards, intercostal muscles allow ribs to return to their resting position. Volume of chest cavity has decreased, which increases the air pressure inside lungs. Air is consequently forced out to make pressure inside and outside the lungs about equal.
  23. 23. Exchange of gases During Inspiration, alveoli are supplied with air high in oxygen and low in carbon dioxide. However, blood in capillaries arriving at the alveoli is low in oxygen and high in carbon dioxide. Different concentrations of oxygen and carbon dioxide result between the blood and air result in a pressure difference. Gases such as oxygen and carbon dioxide move from areas of high concentration or pressure to areas of low concentration or pressure. Oxygen, therefore, moves from the air in the alveoli across the alveolar–capillary wall into the blood, where it attaches itself to haemoglobin in the red blood cells. At the same time, carbon dioxide is unloaded from the blood into the alveoli across the alveolar–capillary wall to be breathed out. This two-way diffusion is known as the exchange of gases (or gaseous exchange).
  24. 24. Exchange of gases, using the same principle, occurs between blood in the capillaries of the arterial system and the cells of the body; for example, the muscle cells. Here, oxygen is unloaded to the cells while carbon dioxide resulting from cell metabolism is given up to the blood. Blood that is high in carbon dioxide content (deoxygenated blood) is carried back to the lungs where it unloads carbon dioxide.
  25. 25. Effect of physical activity on respiration 1) Rate and depth of breathing increase moderately, even before exercise begins, as body’s nervous activity is increased in anticipation of exercise 2) Once exercise starts, the rate and depth of breathing increase rapidly. This is thought to be related to stimulation of the sensory receptors in the body’s joints as a result of movement. Further increases during exercise result mainly from increased concentration of carbon dioxide in the blood, which triggers greater respiratory activity. 3) Increase in rate (frequency) and depth (tidal volume) of breathing provide greater ventilation and occur, generally in proportion to increases in exercise effort.
  26. 26. Components of the blood http://prezi.com/jk1e0tbot9c2/?utm_campaign=share&utm_medium=copy
  27. 27. Structure and function of the heart, arteries, veins and capillaries. Beats70timesperminuteatrest In one day pumps 12000 litres of blood Atria: the upper thin- walled chambers that receive blood coming back to the heart Ventricles: the lower, thick-walled chambers that pump blood from the heart to the body.
  28. 28. Structure and function of the heart, arteries, veins and capillaries. Beats70timesperminuteatrest In one day pumps 12000 litres of blood Atria: the upper thin- walled chambers that receive blood coming back to the heart Ventricles: the lower, thick-walled chambers that pump blood from the heart to the body.
  29. 29. Action of the heart The heart is able to receive and pump blood through a process called the cardiac cycle. The cardiac cycle consists of the: Diastole (relaxation of filling) phase: Muscles of both atria and ventricles relax. Blood returning from lungs and body, flows in to fill both atria and ventricles in preparation for systole (contraction) Systole (contraction or pumping) phase: The atria contracts to further fill ventricles. The ventricles then contract and push blood under pressure to the lungs and all parts of the body. As they contract, the rising pressure in the ventricles closes the atrioventricular valves (between atrium and ventricle) and opens the valves in the arteries leaving the heart (aorta and pulmonary artery).
  30. 30. Blood Vessels Arteries: are blood vessels that carry blood away from the heart Capillaries: are the smallest blood vessels. They function to exchange oxygen and nutrients for waste. http://www.youtube.com/watch?v=CjNKbL_-cwA&feature=related
  31. 31. Blood Vessels Veins: carry deoxygenated blood from the body tissues back to the right atrium. Pulmonary veins from the lungs differ in that they carry oxygenated blood to the left atrium.
  32. 32. Pulmonary and systemic circulation Pulmonary Circulation: is the flow of blood from the heart to the lungs and back to the heart. The right side receives venous blood that is low in oxygen content (deoxygenated) from all parts of the body and pumps it to the lungs. Systemic circulation: is the flow of blood from the heart to the body tissue and back to the heart. The left side of the heart reives blood high in oxygen content (oxygenated) from the lungs and pumps it around the body
  33. 33. What is blood pressure? Blood pressure is the force exerted by the blood on the walls of the arteries. It is measured at two points during the beating of the heart. Systolic Pressure: is the highest (peak) pressure recorded when blood is forced into the arteries during contraction of the left ventricle (systole) Diastolic Pressure: is the minimum or lowest pressure recorded when the heart is relaxing and filling (diastole) Blood pressure is measured in millimetres of mercury by an inflatable cuff wrapped around your upper arm. This is called a Sphygmomanometer. The “normal” blood pressure range is 120/80. 120 is the systolic pressure (contraction) and the 80 is the diastolic pressure (relaxing & filling)
  34. 34. What impacts blood pressure? Blood pressure generally reflects the quality of blood being pushed out of the heart (cardiac output) and the ease of difficulty that blood encounters passing through arteries (resistance to flow). It can be affected by: •Cardiac output: increase in cardiac output = increase in blood pressure •Volume of blood in circulation: water retention (salt intake is high) increases BP; blood loss decreases blood pressure. •Resistance to blood flow: viscosity (stickiness) of blood increases BP as resistance increases, such as during dehydration. Narrowing of blood vessels due to fatty deposits affect blood flow. •Venous return as it impacts cardiac output, it similarly impacts blood pressure. How to measure blood pressure? http://www.youtube.com/watch?v=1IOKUhaYZHw&feature=related
  35. 35. Physical fitness is important in establishing and maintaining total body health. Physical fitness has a number of components which contribute to total body fitness. These components can be grouped into health related components and skill related components. Health Related Components are related to our personal health and can reduce the event of lifestyle diseases occurring such as heart disease, obesity, and diabetes. The health related components are:- - Cardiorespiratory Endurance - Muscular Strength - Muscular Endurance - Flexibility - Body Composition
  36. 36. Health –related fitness components respond positively to physical exercise. For example, exercise can help us lose weight, improve muscle tone and assist in prevention of lower back pain. However, exercise should not be considered in isolation. Other factors such as heredity, environment, nutrition and lifestyle practices all contribute to total body health.
  37. 37. Skill Related Components are related to sports performance and the ability to execute activities. The skill related components are:- - Power - Agility - Coordination - Balance - Reaction Time - Speed An improvement in health-related fitness components improves personal health and lifestyle including lowering the risk of hypokinetic disease. Hypokinetic diseases is a term given to modern lifestyle diseases associated with inactivity. These include condition such as: heart disease, obesity, high blood pressure, insomnia, diabetes and depression
  38. 38. Component Definition Important in … Suitable test Cardiorespiratory endurance The ability of the heart, lungs, and circulatory system to supply oxygen and nutrients efficiently to working muscles and remove waste products. Endurance events such as cycling, triathlons, and marathon running Multistage fitness test 1.6km run Step test Muscular strength The ability to exert force against a resistance in a single maximal effort. -> improves performance and reduces the risk of injury Weightlifting, gymnastics, rugby Dynamometers 1 RM tests Muscular endurance The ability to sustain or repeat a muscular effort for a relatively long period of time. Cycling, cross-country running, skiing, rowing Sit-up test Push-up test Flexibility Range of motion about a joint. -> helps prevent injury, improves posture Most sports Sit-and-reach test Body composition Refers to the percentage of fat as opposed to lean body mass (bone, muscle, organs, connective tissue). Health and physical performance BMI Skinfold tests Power The combination of strength and speed in an explosive action. Running, throwing, jumping Standing long jump Vertical jump Agility The ability to change direction with speed. Team sports Illinois agility run Coordination Smooth, well controlled movements. -> requires good interaction between the brain and muscles All sports Hand wall toss Balance The ability to maintain equilibrium while either stationary (static) or moving (dynamic). All activities Stork stand Reaction time The time taken to respond to a stimulus. Starts in athletics and swimming, shooting Ruler test Speed The ability to perform body movements quickly. Sprint events, team games 50m sprint
  39. 39. 15 minute challenge: You have 15 minutes to put together a PowerPoint presentation on your component of fitness you have selected. Your PowerPoint can be no longer than 4 slides. (4 SLIDES ONLY FERAH =p). And can only go for 5 minutes. You must cover the following areas: 1)Define component and any key terms. 2) Outline it’s importance to health/impact on body 3) Describe the fitness test 4) Outlines ratings for given fitness test (ie. What constitutes poor/fair/average/good/excellent) PROPS WILL BE MADE AVAILABLE FOR PRESENTATION
  40. 40. Training programs aim to develop a range of fitness and skill components. To develop an effective training program it is necessary to identify the correct energy pathway. An energy pathway is a system that converts nutrients to energy for exercise. If we perform short sharp movements as in jumping and lifting, the body uses the anaerobic pathway to supply energy. Anaerobic means ‘in the absence of oxygen’. If movements are sustained and of moderate intensity, the aerobic pathway supplies the bulk of the energy needs. Aerobic means ‘with oxygen”
  41. 41. Aerobic Training Aerobic exercise refers to exercise that is dependent on oxygen utilistaion by the body to enable muscular work. Activity that is of low to moderate intensity and continues for 90 seconds or more is generally termed aerobic because oxygen becomes available to the cells of working muscles for energy generation Walking, marathon running and the 1500 metres in swimming are examples of activities that require a high degree of aerobic fitness. To improve aerobic fitness we need to: •Engage in activities that are continuous and of long duration. Cross-country running, sand-hill running, cycling and jogging are examples of activities that develop our aerobic energy system •Use the FITT principle to develop an aerobic program to suit our needs. The principle provides guidelines for individuals who aim to improve cardiorespiratory fitness and some forms of resistance training. It ensures a program has the quantity and quality of movement necessary to produce the desired physical improvement.
  42. 42. Frequency This refers to how many times per week we train. For improvement to occur, individuals must train on at least 3 occasions per week. This can be increased to five, but the benefit to be gained from sessions in excess of this is minimal. The aim is for a training session to sufficiently stress body systems, causing a response called adaptation. An adaptation refers to an adjustment made by the body as a result of exposure to progressive increases in the intensity of training. This is an adjustment made by the body as a result of exposure to progressive increases in intensity of training. For resistance training, 3 sessions are sufficient, 4 is maximal, allowing rest days in between for muscle fibres to regenerate.
  43. 43. Intensity This refers to how hard we work during each training session or the amount of effort required be an individual to accrue a fitness benefit. The most accurate way of measuring intensity during aerobic exercise is by calculating your target heart rate and using this as a guide. The target heart rate together with the area above and below is called the target heart rate zone. When exercising, the level of intensity needs to be sufficient to keep the heart rate within the target heart rate zone for the required period of time. The level of intensity is established in terms of heart rate, which is calculated in beats per minute (bpm). There are two important steps that need to be taken to calculate your target heart rate zone. 1. Determine your maximum heart rate. To do this, simply subtract your age from 220. Hence, a 20-year-old person would have a maximum heart rate of 200 beats per minute. 2. Determine the percentage of your maximal heart rate relevant to your fitness. If your fitness is poor, work at 50 to 70 per cent of your maximum heart rate. If your fitness is good, work at 70 to 85 per cent of your maximum heart rate. If uncertain, work at the lower level and gradually increase the level of intensity. •For aerobic fitness we need to increase out heart rate to around 60 – 80% of our maximum heart rate of 220 beats per minutes (less our age). This is known as the training zone and it will mean we gain a training effect for our hearts and our lungs. To work this out, use the following examples – –220 minus your age (15 years) = 205 (maximum HR) –60% of 205 = 123 beats per minute –80% of 208 = 164 beats per minute
  44. 44. Time •This refers to the period of time that you exercise for continuously. A base line level of 20 minutes is needed to secure an aerobic training effect There is little sense in exercising for periods longer than 60 minutes or to exhaustion as this carries the risk of overtraining and the possible development of overuse injuries (elite athletes excepted). 30–45 minutes is generally sufficient and will depend on the intensity of exercise.
  45. 45. Type •This refers to the type of exercise performed. Based on factors such as areas that need improvement or type of sport. They type of exercise should align with the type of sport or area of improvement you. For example, A swimmer is an Aerobic activity, requiring cardiorespiratory efficiency. Therefore there training program should involved aerobic activities that target the cardiorespiratory system.
  46. 46. Anaerobic means ‘in the absence of oxygen’. In anaerobic activity, the intensity level is much higher and the effort period much shorter than required in aerobic activity. In general, activity that lasts for two minutes or less and is of high intensity is called anaerobic because muscular work takes place without oxygen being present. Anaerobic exertion requires specialised training to generate the adaptations necessary for muscular work without oxygen. Training enhances the ability of muscle cells to improve their use of fuel reserves and be more efficient in converting blood sugar to energy during intense exercise.
  47. 47. To improve anaerobic fitness, we need to: •work hard at performing and enduring specific anaerobic movements such as lifting weights, throwing or jumping •practise the required movements at or close to competition speed to encourage the correct adaptations to occur •use activities such as interval training where periods of intense work are interspersed with short rests to train the anaerobic system to supply sufficient fuel utilise resistance (weight) training exercises to further develop the muscles required for the movement •train to improve the body’s ability to recharge itself; that is, to decrease recovery time after short periods of intense exercise •train to improve the body’s ability to tolerate higher levels of lactic acid, a performance use crippling substance that builds up in the muscles following intense exercise •gradually develop the body’s ability to utilise and/or dispose of waste that is created by intense exercise.
  48. 48. Training programs are all about meeting the specific needs of the individual, their chosen activity and goals. Some sports require a high level of aerobic fitness and a general level of anaerobic fitness while the reverse is true of others. Games such as touch football, soccer and netball are characterised by periods of moderate intensity interspersed with periods of high intensity. While the amount of aerobic/anaerobic fitness varies according to the game, it is also affected by the position of the player, each individual’s effort and their base fitness level. The sprint in rugby, rally in tennis and man-to-man defence in basketball are all highly demanding, causing muscles to use available fuel and then requiring cells to find other sources for energy supply. The change between aerobic and anaerobic energy supply is gradual rather than abrupt. When engaged in activity, the body switches between systems according to the intensity of exercise, with one system being predominant and the other always working but not being the major supplier of energy. A sprint during a touch football game requires anaerobic energy due to the instant and heavy demands made on the muscles involved in the movement. During this period, the aerobic system is still functioning, but is not the major energy supplier.
  49. 49. Select one of the following sports: soccer, netball, rugby league Select a specific position: goal keeper, centre, half-back Answer the following questions using specific examples 1) During which play/movement sequence is the aerobic system utilised? 2) During which play/movement sequence is the anaerobic system utilised? 3) Describe a movement/play sequence when both the aerobic and anaerobic systems would be utilised?
  50. 50. Based on your given component, use Publisher to design an informative newsletter page You need to answer the following areas: 1)Define component, give any key terms 2)Outline calculations used 3)Describe the impact training has on the given component Due Friday, June 1st ,2012
  51. 51. Biomechanics is the science concerned with forces and the effect of these forces on and within the human body. A knowledge of biomechanics helps us to: • choose the best technique to achieve our best performance with consideration to our body shape. For instance, an understanding of the biomechanical principles that affect athletic movements, such as the high jump, discus throw, golf swing and netball shot, improve the efficiency with which these movements are made. This improves how well we perform the skill. • reduce the risk of injury by improving the way we move • design and use equipment that contributes to improved performance.
  52. 52. Motion is the movement of the body from one position to another Some bodies are inanimate (non-living) such as basketballs, shot puts; whilst other bodies are animate (living) such as golfers, footballers. Motion itself can be divided into 3 categories: •Linear •Angular •General
  53. 53. Linear motion takes place when a body and all parts connected to it travel the same distance in the same direction and at the same speed. The easiest way to determine if a body is experiencing linear motion is to draw a line connecting two parts of the body; for example, the neck and hips. If the line remains in the same position when the body moves from one position to another, the motion is linear.
  54. 54. Angular motion the motion of a body about a fixed point or fixed axis. Angular movement plays the dominant role because most of an athlete’s movements result from the swinging, turning action of the athlete’s limbs as they rotate around the joints. Many terms are used to refer to angular motion. Movements include rotating, spinning, swinging, circling, turning, rolling, pirouetting, somersaulting and twisting. All of these terms indicate that an object or an athlete is turning through an angle, or number of degrees. In sports such as gymnastics, skateboarding, basketball, diving, figure skating, and ballet, the movements used by athletes include quarter turns (90 degrees); half turns (180 degrees); and full turns, or “revs” (revolutions), which are multiples of 360 degrees
  55. 55. General motion a mix of linear and angular, which we simply call general motion. In sport, a mix of linear and angular movement is most common. Even those sport skills that require an athlete to hold a set position involve various amounts of linear and angular motion. For example, a gymnast balancing on a beam. In maintaining balance on the beam, the gymnast still moves, however slightly. This movement may contain some linear motion but will be made up primarily of angular motion occurring around the axes of the gymnast’s joints and where the gymnast’s feet contact the beam. Perhaps the most visible combination of angular and linear motion occurs in a wheelchair race. The swinging, repetitive angular motion of the athlete’s arms rotates the wheels. The motion of the wheels carries both the athlete and the chair along the track. Down the straightaway, the athlete and chair can be moving in a linear fashion. At the same time the wheels and the athlete’s arms exhibit angular motion
  56. 56. ; Improving performance in activities that encompass linear motion usually focuses on modifying or eliminating technique faults that contribute to any non-linear movements. Excessive up and down, rotational and lateral movements are examples of faults that erode performance directed towards achieving the shortest, most efficient pathway. Swimmers who use an irregular arm pull that results in a zigzag movement pattern along the pool surface are examples of poor application of linear motion. Homework Tip: For swimmers, excessive movement increases drag which slows down a swimmer. But what is drag and how does a swimmer eliminate it to enhance their swimming? Reference: http://library.thinkquest.org/06aug/02165/physics_of_swimming.htm
  57. 57. How motion is classified depends on the path followed by the moving object. We will focus on linear motion in a range of sporting activities and apply the principle to enhancing performance. Velocity is equal to displacement divided by time. Displacement is the movement of a body from one location to another in a particular direction, or an ‘as the crow flies’ measurement. Velocity is used for calculations where the object or person does not move in a straight line. An example is a runner in a cross-country race. Activities to improve speed may also relate to velocity. Improving the velocity of implements such as javelins or arrows requires specialised training, as does improving the performance of athletes in non-linear events such as marathons.
  58. 58. Speed is equal to the distance covered divided by the time taken to cover distance So, if a runner runs 100m in 12 secs Speed is important in most sports and team games. The player who can move quickly has a distinct advantage in games such as touch football, rugby and soccer because not only is that player difficult to catch, but he/she can use their speed to gather opponents quickly in defence. Much of our potential for speed is genetic and relates to the type of muscle fibre in our bodies. However, individuals can develop their speed as a result of training and technique improvements, the basis of which is the development of power and efficiency of movement.
  59. 59. Momentum the quantity of motion the body possesses Mass refers to the amount of matter in a body The application of the principle of momentum is most significant in impact or collision situations. The principle can be applied to certain sporting games such as rugby league and rugby union, where collisions in the form of tackles are part of the game. However, collisions between players in sporting events tend to exhibit different characteristics to that of objects due to a range of factors, including: •the mass differences of the players — in most sports, we do not see the huge variations in mass that we find between cars, bicycles and similar objects • elasticity — the soft tissue of the body, which includes muscle, tendons and ligaments, absorbs much of the impact. It acts as a cushion. • evasive skills of players which often result in the collision not being ‘head-on’. In some cases there may be some entanglement just prior to collision, such as a palm-off or fend. This lessens the force of impact. The momentum described in the previous situation is called linear momentum because the object or person is moving in a straight line.
  60. 60. There are numerous instances in sport where bodies generate momentum but they do not travel in a straight line; for example, a diver performing a somersault with a full twist, football kick, discus throw and golf swing. In each of these cases, the body, part of it, or an attachment to it such as a golf club or tennis racquet, is rotating. We call this angular momentum. Angular momentum is the quantity of angular motion in a body or part of a body Angular momentum is affected by: • angular velocity For example, the distance we can hit a golf ball is determined by the speed at which we can move the club head. • the mass of the object. The greater the mass of the object, the more effort we need to make to increase the angular velocity. It is relatively easy to swing a small object such as a whistle on the end of a cord. Imagine the effort that would be needed to swing a shot-put on a cord. • the location of the mass in respect to the axis of rotation. With most sport equipment, the centre of mass is located at a point where the player is able to have control and impart considerable speed. Take baseball bats and golf clubs for example. Here, the centre of mass is well down the shaft on both pieces of equipment. This location enables the player to deliver force by combining the mass of the implement at speed in a controlled manner, thereby maximising distance.
  61. 61. ; The centre of gravity of an object is the point at which all the weight is evenly distributed and about which the object is balanced. If the object is spherical, it’s centre of gravity is directly in the the centre however, some objects used in sport are not perfectly spherical or do not have an evenly distributed mass ie. lawn bowl. When rolled on a flat surface, the object will have a slight ‘bias’ to where the mass has been redistributed. In the human body, the position of the centre of gravity depends upon how the body parts are arranged; that is, the position of the arms and legs relative to the trunk. Because the human body is flexible and can assume a variety of positions, the location of the centre of gravity can vary. It can even move outside the body during certain movements.
  62. 62. ; Varying the centre of gravity in the execution of a skill can enhance performance. Skilled high jumpers and long jumpers both lower the centre of gravity in the step or steps immediately preceding take-off. This enables them to propel their body over a slightly longer vertical path than would otherwise be possible. Static balance activities such as headstands and handstands require precise manipulation of the centre of gravity. Dynamic balance activities also require skilful control of the centre of gravity. In many moving activities, such as skiing and surfing, there is a fine line between the balance necessary for control and loss of balance resulting in a fall.
  63. 63. ; The line of gravity is an imaginary vertical line passing through the centre of gravity and extending to the ground. It indicates the direction that gravity is acting on the body. When we are standing erect the line of gravity dissects the centre of gravity so that we are perfectly balanced over our base of support. Our base of support has a limited area. Widening our stance increases the size of the base of support. However, rules of some sports and competitions limit the size of the base of support; for example, the starting blocks in athletics. The closer the line of gravity moves to the outer limits of the base of support, the less stable we become. Movement results in a momentary state of imbalance being created, causing the body to move in the direction of the imbalance. In specialised sporting movements, such as the start in athletics, the precision with which the line of gravity moves in relation to the base of support directly affects the quantity and quality of movement. During practice of specialised skills, athletes progressively develop a feel for the line of gravity relative to the base of support, enabling the controlled instability required for movement. This means that less force is required to initiate the desired movement.
  64. 64. ; The base of support refers to an imaginary area that surrounds the outside edge of the body when it is in contact with a surface. It affects our stability or our ability to control equilibrium. A wide base of support is essential for stability because the centre of gravity is located well within the boundaries. There are many examples where athletes use the base of support to their advantage. • The gymnast performing a pirouette has a very narrow base of support and must work hard to ensure that their centre of gravity remains within the base. • Wrestlers widen their base of support to prevent their opponents from moving them into a disadvantageous position. • Tennis players lower the centre of gravity and widen the base of support in preparation to receive a fast serve. This enhances balance and enables the centre of gravity to be moved in the desired direction more readily. • Swimmers on the blocks widen their feet and move the centre of gravity forward to improve their acceleration. • Golfers spread their feet to at least the width of their shoulders to enhance balance when they rotate their body during the swing.
  65. 65. ; 1) Define: a) Force b) Power 2) Explain the difference between an internal and external force and their impact on movement. Give examples.
  66. 66. ; Force (biomechanics) is the push or pull acting on a body Internal forces are those that develop within the body; that is, by the contraction of a muscle group causing a joint angle to decrease (for example, the contraction of the quadriceps when kicking a football) External forces come from outside the body and act on it in one way or another. For example, gravity is an external force that acts to prevent objects from leaving the ground Internal forces External forces Muscle contractions Gravity Muscle tension Air resistance Joint force/movement Water resistance Friction
  67. 67. ; There are two types of forces: Applied Force are forces generated by muscles working on joints. Applied forces are forces applied to surfaces such as a running track or to equipment such as a barbell. ; When this happens, a similar force opposes it from outside the body. This is called a reaction force. Reaction Forces are equal and opposite forces exerted in response to applied forces. The result is that the runner is able to propel his or her body along the track surface because the applied force generated by the legs is being matched equally by the reaction force coming from the track surface. This is explained by Newton’s third law: ‘For every action, there is an equal and opposite reaction’. In other words, both the runner and the track each exert a force equal to whatever force is being applied.
  68. 68. ; We see evidence of the application of force in all physical activity. Consider the following examples: the high jumper, discus thrower, cricket bowler and basketball player all exert forces when executing movement skills.
  69. 69. ; Power (biomechanics) is the ability of muscle groups to contract at speed. To propel the body higher as in high jumping, faster as in running, or further as in long jumping, we need to develop power. Power is expressed by the formula An increase in strength (force) or an increase in the speed at which muscles shorten results in an increase in power. While an increase in both causes an increase in overall power, the athlete must decide which component (strength or speed of muscular contraction) is of greatest benefit. Jumpers and runners need to focus on rapid muscular contraction while controlling the strength aspect. This is called speed-dominated power. In contrast, the weight-lifter needs power and must be able to lift the weight. He or she needs to develop strength- dominated power.
  70. 70. ; Forces exerted on the body are absorbed through the joints, which bend or flex in response to the impact. Joint flexion helps prevent injury to surrounding tissue. With inanimate objects, techniques have been developed to absorb their impact. There are principles to remember with the application of force on an object: 1)The quantity of force applied to the object is important. The greater the force, the greater is the acceleration of the object 2)If the mass of an object is increased, more force is needed to move the object the same distance. For example, if a football becomes heavier as a result of wet conditions, more force is required to pass or kick it. 3)Objects of greater mass require more force to move them than objects of smaller mass. The size of the discus, javelin and shot-put is smaller for younger students than older students. This assumes that older students have greater mass and are thereby able to deliver more force than younger students because of their increased size (mass) and (possibly) strength. In many sports and activities, the body rotates about an axis. When this happens centripetal force and centrifugal force are experienced.
  71. 71. ; Centripetal force is a force directed towards the centre of a rotating body. Centrifugal force is a force directed away from the centre of a rotating body. These forces commonly occur with skills that require rotation such as the golf swing or the hammer throw. To manage centripetal and centrifugal forces in sporting situations it is important to: • begin carefully so that you learn to feel the forces as they develop • respond gradually, trying to match the force exactly • work on your balance so that you become comfortable leaning beyond where you would normally be balanced • ensure you have a firm handgrip if holding an object such as a bat or high bar • bend your knees and ensure you have good traction if working on a track, field or circuit.

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