How do the musculoskeletal and cardiorespiratory systems ...



Preliminary Core 2: The Body in MotionHow do the musculoskeletal and cardiorespiratory systems of the body influence and respond to movement?Skeletal SystemMajor bones involved in movementBones have five main functions including:Support for the body, giving it shape, form and postureProtection of vital organs and soft tissueAssistance in body movement: Provide the attachment for muscles and serve as leversManufacture of blood cells in the marrow cavitiesProvision of a storehouse for essential minerals such as calcium and phosphorus34290006858000Important TermsLong and short bones: Function has levers or to transfer forcesFlat bones: Provide protection for organsCartilage: Prevents jarring and allows bones to move freely on each otherAnatomical TermsSuperior Towards the headInferior Towards the feetAnterior Towards the front Posterior Towards the backMedial Towards the midline of the bodyLateral Towards the side of the bodyProximal Towards the body’s massDistal Away from the body’s massStructure and Function of Synovial JointsFibrous Joint Immovable joint where no movement is possible Eg. Bones of the craniumCartilaginous Joint Slightly moveable that permits limited movement Eg. In the vertebral columnSynovial Joint Freely moveable that allows maximum movement Eg. Hip jointLigaments Fibrous bands that connect the articulating bones Maintain stability in the joint by restricting excessive movementTendons Tough, elastic cords of tissue Attach muscle to boneSynovial Fluid Act as a lubricant, keeping joints well oiled and moving surfaces apart Forms a fluid cushion between two joint surfaces Provides nutrition for the cartilage and carries away waste productsDescribe the function of the main structures of a synovial joint. (4 Marks)A synovial joint is one that is freely movable and thus allows maximum movement. It consists of ligaments, tendons and synovial fluid. An example of this is the hip joint, which contains ligaments, tendons, synovial fluid and cartilage. First of all, ligaments are fibrous bands that connect articulating bones and help to maintain stability in the joint by restricting excessive movement. Furthermore, the tendons are tough, elastic cords that attach muscle to bone to allow movement of the skeletal system. The synovial fluid acts as a lubricant between the joint, hence acts as a fluid cushion between the two joint surfaces. Finally, cartilage covers the surface of bones to further allow bones to move freely over each other and hence produce maximum movement.Explain how synovial joints allow human movement. (4 Marks)A synovial joint is one that is freely movable and thus allows maximum movement. Examples of synovial joints include the knee and elbow joints. Within a synovial joint, ligaments connect articulating bones and help to maintain stability in the joint during movement by restricting excessive movement while tendons attach muscle to bone. For example, the elbow is a synovial joint where the bicep and tricep muscles are attached to the radius, ulna and the scapula bone in the shoulder via tendons. During flexion and extension, the tendons pull on the bones to produce movement whilst ligaments between the humerus and ulna help to stabilise the joint during movement. 046355000Joint actions (eg. extension and flexion)Identify the location and type of major bones involved in movementEg. long bones articulate at hinge joints for flexion and extensionBall and socketFlexion and extensionAbduction and adductionCircumductionShoulderHipsHingeFlexion and extensionElbowKneeFingersPivotRotationNeckForearmSlidingSlight sliding movementsVertebrateBones of the wristSaddleFlexion and extensionAbduction and adductionCircumductionThumbMuscular SystemMajor Muscles Involved in Movement07810500Muscle Relationship (agonist, antagonist)Agonist Muscle that causes the major action; one that contracts (eg. bicep during flexion)Antagonist Muscle that relaxes and lengthens to allow agonist muscle to contractThat is, antagonist muscles cause an opposite action to that cause by the agonist (eg. triceps)Stabiliser Fixator muscles that act at a joint to stabilise itWith reference to one of the following images, or muscle groups you have studied, describe the relationship between agonist and antagonist muscles. (3 Marks)2286007302500To produce movement, agonist muscles contract to cause the major action while antagonist muscles relax and lengthen to help control the action being made. In the first image, image A portrays the extension of the elbow and thus the triceps act as the agonist muscles and contract while the biceps act as antagonist muscles to relax and lengthen. In image B, during flexion of the elbow, the biceps act as antagonist muscles while the triceps act as antagonist muscles.Type of Muscle Contraction (concentric, eccentric, isometric)Isotonic (AKA Dynamic): Length of the muscle will change, becoming longer or shorterConcentric Muscles shorten to cause movement at the jointEccentric Muscle lengthens while under tension; often happens with assistance of gravityIsometric Muscle fibres activate and develop force but muscle length does not changeDescribe how the skeletal and muscular body systems work together to enable movement. (3 Marks)The skeletal system relies on synovial joints to allow movement of the bones. The muscular system works together with the skeletal system in order to produce movement. This is done by muscles, which are attached to bones and the muscles pull on the bones, resulting in movement. The muscles that pull on bones to produce a contraction movement are called agonist muscles whilst antagonist muscles relax and lengthen to produce an extension movement. For example, during flexion of the elbow, the biceps act as agonist muscles to contract and triceps act as antagonist muscles to relax. Respiratory SystemStructure and Function0115570Nasal Passages- Hair traps dust, which is sneezed out- Air is warmed and filtered to provide optimum conditions for gaseous exchange00Nasal Passages- Hair traps dust, which is sneezed out- Air is warmed and filtered to provide optimum conditions for gaseous exchange3048001905Bronchi- Air passageways- Sends air to alveoli via bronchioles00Bronchi- Air passageways- Sends air to alveoli via bronchioles-3009900177165Pharynx- Conducting tube with hairs to filter- Separates food and air00Pharynx- Conducting tube with hairs to filter- Separates food and air762000172085Bronchioles- See “Bronchi”00Bronchioles- See “Bronchi”889000153670Alveoli- Small air sacs with thin walls- Close to capillaries- Place of gaseous exchange00Alveoli- Small air sacs with thin walls- Close to capillaries- Place of gaseous exchange041910Trachea- Allows air to travel to and from the lungs- Lined with mucus secreting cells with hairs that push foreign particles out of the lungs00Trachea- Allows air to travel to and from the lungs- Lined with mucus secreting cells with hairs that push foreign particles out of the lungsLung Function (Inspiration and Expiration)InspirationDiaphragm contracts and flattensExternal intercostal muscles lift ribs up and outThis increases volume of chest cavity and decreases the air pressure in the lungsIn response, air rushes into the lungs via the air passagesExpirationDiaphragm relaxes and moves upInternal intercostal muscles allow the ribs to return to its resting positionChest cavity decreases and so the air pressure inside lungs increases, hence it’s forced outExchange of gases (internal, external)Air breathed in from the atmosphere contains 21% oxygen and 0.03% carbon dioxidePressure of oxygen is high in the alveoli and low in CO2Blood in the capillaries are low in oxygen and high in CO2This causes a pressure differenceOxygen moves from air in alveoli across the alveolar-capillary wall into the capillaryOxygen attached itself to haemoglobin in bloodCO2 unloads from the blood into the alveoli across the alveolar-capillary wallThis equalises the pressure of both oxygen and CO2Analyse the various aspects of lung function through participation in a range of physical activitiesEffect of Physical Activity on the Respiratory SystemRespiratory system is responsible for circulating oxygen around the body and removing CO2During PA, respiratory system increases available O2 to working musclesDuring pre-exercise phase, ventilation slightly increases as an anticipation for exerciseWhen exercise beings, body requires increase of O2 and ventilation increases to respond to O2 needs and requirements of muscles at workHeart rate increases to increase supply of O2 to musclesAfter exercise (recovery period), ventilation falls rapidly as muscles have stopped workingMuscles do not need as much O2 But CO2 needs to be removed and so ventilation rates above rest are neededCirculatory SystemThree parts of the circulatory system:BloodHeartBlood vesselsComponents of BloodFunctions of BloodTransportation of oxygen and nutrients to the tissuesRemoval of carbon dioxide and wastesProtection of the body via the immune system (through clotting to prevent blood loss)Regulation of body’s temperatureComponents of BloodPlasmaContains 90% waterAlso contains proteins, nutrients, hormones, salts and wastesTransports these substances to nourish tissues so they can functionControls body heat through sweatingRed Blood CellsMake up 45% of blood volume and 95% of blood cellsContain iron and a protein called haemoglobinHaemoglobin carries oxygen around the bodyMade in bone marrowWhite Blood CellsFormed in bone marrow and lymph nodesProtects the body from diseasePhagocytes: Engulf foreign materialLymphocytes: Product antibodies to fight diseasePlateletsMade in bone marrowProduce clotting substancesStructure and function of the heart, arteries, veins and capillariesHeartInferior Vena CavaCarries deoxygenated blood from lower half of the bodySuperior Vena CavaCarries deoxygenated blood from upper part of the bodyAortaLargest blood vessel in the bodyCarries oxygenated blood from heart to every cell of the bodyRight AtriumAccepts deoxygenated blood from major veinsPumps collected blood to the right ventricle through the tricuspid valveLeft AtriumReceives oxygenated blood from lungs through pulmonary veinsOxygenated blood passes through bicuspid valve to left ventricleRight VentricleReceives deoxygenated blood from right atriumPumps it into the pulmonary artery to be carried to the lungLeft VentricleReceived oxygenated blood from the left atriumPumps it into the aortaPulmonary ArteryCarries oxygenated blood from right ventricle to lungsPulmonary VeinCarried oxygenated blood from lungs to left atrium’Note: Atrioventricular valves prevent backflow during systole (heart contracts to pump blood)During diastole (heart relaxes and fills), they open to allow blood to flow to the ventriclesArteriesHave thick, strong elastic walls containing smooth muscles to withstand pressure of blood forced through themCarry blood away from the heartEventually branch off into arterioles and then into capillariesVeinsHave thin walls as blood pressure is lowValves in veins prevent backflow of blood during periods when blood pressure changesCarry deoxygenated blood back into the right atriumPulmonary veins carry oxygenated blood from lungs to the left atriumCapillariesSmallest of all blood vessels; link between arterioles and veinsWalls are extremely thin to allow for exchange of substancesFunction: Exchange oxygen and nutrients for wastePulmonary and systematic circulationPulmonary CirculationFlow of blood from the heart to the lungs and back to the heartSystematic CirculationFlow of blood from the heart to the body and back to the heartBlood pressureBlood pressure is determined by:Cardiac output: Increase in cardiac output = Increase in blood pressureVolume of blood in circulation: If blood volume increases due to increase water retention (eg. high salt intake), then blood pressure increasesResistance to blood flow: Increased viscosity of blood results in greater resistance and thus, elevated blood pressureSystolic pressure: Highest pressure recorded when blood is forced into the arteries during contraction of the left ventricleDiastolic pressure: Lowest pressure recorded when the heart is relaxing and fillingBlood vessels (eg. aorta) pump blood around the body and so experienced pressure against their walls; aorta has the highest blood pressureVeins are returning blood back into the right atrium and so have comparably lower pressureVeins rely on muscle contraction to act as a pump Analyse the movement of blood through the body and the influence of the circulatory and respiratory systems on movement efficiency and performanceMovement of blood through the bodyDeoxygenated blood from the body is emptied into the right atrium via the inferior and superior vena cavaBlood travels to the right ventricle through the tricuspid valvePulmonary artery carries the deoxygenated blood to the lungs for oxygenationPulmonary vein carries the oxygenated blood from the lungs to the left atriumBlood travels to the left ventricle through the bicuspid valveOxygenated blood is pumped through the aorta to the rest of the bodyExplain how lung respiration is affected by increasing physical activityLung respiration includes inspiration and expirationDuring physical activity, the working muscles require more oxygenHence inspiration and expiration increases in order to increase the intake of oxygen and the removal of wastes such as carbon dioxideHeart rate also increases to pump oxygenated blood to the working musclesAs physical activity increases, depth of breathing also increases in an attempt to maximise oxygen intake and CO2 expirationAmount of physical activity a person normally undertakes also affects lung respirationMore fit person will be able to efficiently exchange gases compared to a sedentary individualWhat is the relationship between physical fitness, training and movement efficiency?Health-related components of physical fitnessCardiorespiratory endurance – Beep testAKA aerobic powerAbility to working muscles to take up and use oxygen that has been breathed in during exerciseProvides the necessary nutrients and O2 to cells during exerciseImportant in: Endurance events such as cycling and marathonsMuscular strength – Hand dynamometerAbility to exert force against a resistance in a single maximal effortSufficient strength enables efficient movement and reduces the incidence of injuryHand dynamometerImportant in: Weight lifting, gymnastics and rugbyMuscular endurance – Sit-up testAbility of muscles to endure physical activity for extended periods of time without undue fatigueWithout it, technique deteriorates and efficient movement is jeopardised and the likelihood of injury increasesImportant in: Cycling, cross-country running and rowingFlexibility – Sit and reach testRange of motion about a joint OR the ease of joint movementHelps to prevent soft tissue injury and improve blood circulationCan strengthen the muscle if combined with isometric exercisesBody composition – Skin fold callipers or BMIPercentage of fat as opposed to lean body mass in a personExcessive storage of fat places additional strain on jointsAnalyse the relationship between physical fitness and movement efficiency. Students should consider the question, “To what degree is fitness a predictor of performance?” (Relate all points together – See textbook and workbook for sample answers)Skill related components of physical fitnessPowerAbility to combine strength and speed in an explosive actionVertical jump test or standing long jumpSpeedAbility to perform body movements quickly50m sprintAgilityAbility to move body from one position and direction to another with speed and precisionShuttle runCoordinationAbility to harmonise the messages from the senses with parts of the body to produce smooth and well controlled movementsEnables athletes to learn more skills quicker and perform acquired skills more consistentlyAlso decreases chance of injuryJuggling with one handBalanceAbility to maintain equilibrium while either stationary or movingPoor balance can lead to falls, poor technique and inferior skill executionStork standReaction timeTime taken to respond to a stimulusSlow reaction time leads to poor skill execution and increased risk of injuryRuler testThink critically about the purpose and benefits of testing physical fitnessOutline advantages and disadvantages of fitness testing. (5 Marks)ADVANTAGESFitness testing examines an individual’s ability of health-related and skill-related physical fitness including muscular strength and endurance as well as coordination and agility. The benefits of fitness testing are that it allows individuals to discover their strengths and weaknesses regarding their body and hence act accordingly to ensure maximum movement efficient without the risk of injury. For example, a rugby player would undertake the beep test to test their cardiorespiratory endurance whilst a sit up test would help to determine their muscular endurance. As a result, they’ll be able to monitor their progress and hence structure effective training programs to enhance their sport performance. DISADVANTAGESWhile fitness testing are generally quick and easy methods at assessing one’s fitness in the various areas, there are also some disadvantages associated with some of the tests . For example, the sit and reach test is a quick and easy method of determining one’s flexibility. Generally, being able to touch your toes is an average result. However, people with long arms in proportion to their legs may find this task easier and so it can produce unreliable results as it’s not truly testing one’s flexibility. Furthermore, the muscle strength test is using a hand dynamometer, which in turn provides a value of forearm strength. However, some people have may stronger leg muscles due to running and thus, this test does not cater for all types of strength. Finally, any fitness tests that involve the use of time as measurement may not be an accurate representation of the person’s speed as reaction time, another fitness component is a factor in play. If a person has slow reaction time but fast speed in a sprint test, this may affect their results as they’ll achieve a slower time overall.Aerobic and anaerobic trainingFITT PrincipleFrequency Must train at least 3 occasions a week, but can increase to 5Aim to stress the body systems and cause an adaptationResistance training: 3 sessions are sufficient while 4 is maximal to allow rest days in between for muscle fibre to regenerateIntensityAmount of effort required to gain a fitness benefitMeasuring intensity (aerobic activity): Use target heart rate zone as a guideTarget HR zone: Area surrounding target HR; use percentages of MHRMHR – 220bpm subtract your agePoor fitness: Work at 50-70% of MHRGood fitness: Work at 70-85% of MHRResistance training: Intensity is established by varying load, repetition, sets or the rest periodTimeGood health: Last 20 to 30 minutesCan increase to 40 minutes60 minutes+ can lead to overtraining and possible development of overuse injuriesNone of these times include warming up and cooling downDuration: 6 weeks is the minimal period for realisation of a training effectTypeBest type is continuous exercise that use large muscle groupsEg. Running, cycling, swimming and aerobicsThese activities draw heavily on our oxygen supplyHence increases breathing rate, heart rate and blood flow to the working musclesAerobic fitness improves as cardiorespiratory system adaptsResistance training: Low resistance with high repetitions is preferableCan be provided using many activities such as circuit training and resistance bandsDesign an aerobic training session based on the FITT principleHow is the FITT principle used to improve aerobic training? (4 Marks)The FITT principle involves adjusting the frequency, intensity, time and type of exercise in accordance to a person’s training program or need to improve particular fitness component such as cardiorespiratory endurance. In order to improve aerobic training, an individual should train at least 3 times a week though this can be increased to 5 sessions. Training 3-5 times a week aims to stress the body systems and as a result, cause an adaptation. Meanwhile, the intensity a person should train at ranges from 50-85% of their maximal heart rate, depending on their current level of fitness; person with poor fitness should work at about 50-75% of their MHR while those with good fitness can extend it to 70-85% of their MHR. Furthermore, to improve aerobic training, sessions should last between 20-30 minutes, though should not exceed 60 minutes as this can lead to overtraining. Finally, the best type in this scenario should be continuous exercises that utilise the large muscle groups including running and cycling. Since these activities draw heavily on our oxygen supply, it will hence improve our cardiorespiratory system by causing it to adapt. Compare the relative importance of aerobic and anaerobic training for different sportsEg. Gymnastics versus soccerCompare the importance of aerobic AND anaerobic training in TWO different sports/physical activities. (6 Marks)Depending upon what type of exercise an individual undertakes and at what intensity they’re working at will determine if it’s aerobic or anaerobic in nature. Typically, aerobic training includes swimming and cross country running, where an individual works at approximately 70-85% of their maximal heart rate (MHR) at a low to moderate intensity and lasts for approximately 30 minutes. These exercises are aerobic as they utilise the large muscle groups such as our quadriceps and hamstrings in running whilst our biceps and triceps are also used in swimming. Due to the use of large muscle groups, these activities draw heavily upon our oxygen supply in order to supply the working muscles with the oxygen needed to function. Since cross-country running also improves muscular endurance of the hamstrings and quadriceps, anaerobic training in the form of resistance training may prove to be useful in improving muscular strength and endurance. On the other hand, resistance training of the forearm may be useful for swimming as it can provide more power with each stroke, and thus provide more thrust to propel the swimmer forward. Meanwhile, anaerobic training such as sprints and weight training work in the anaerobic threshold above 85% of an individual’s MHR. The main difference between anaerobic and aerobic training is that anaerobic involves high intensity with repetitions but in a shorter time span as it focuses on working with the absence of oxygen. As a result, circuit training with 2-minute exercises and short intervals in between are useful for anaerobic training, as anything more than 2-minutes may turn into aerobic training. This type of training is typically used by athletes to promote strength, speed and power while body builders perform weight training to build muscle mass. In these scenarios, aerobic training does not have an impact on the performance of an individual who aims to improve the stated fitness components and thus, does not play a part at all during anaerobic exercise.Overall, depending upon the type of sport or physical activity an individual participates in will determine if they should undergo aerobic or anaerobic training to enhance their performance. That is, aerobic training focuses on cardiorespiratory and muscular endurance while anaerobic training mainly improves muscular strength, speed and power. Complete the following table to illustrate some differences between aerobic and anaerobic training. (3 Marks)AerobicAnaerobicTraining IntensityLow to moderate intensityHigh intensityType of activityContinuous exercise that utilise the large muscle groupseg. running, cycling and swimmingLarge number of repetitions with low weightsEg. Lifting dumbbells, resistance bands, circuit trainingTargeted fitness componentsCardiorespiratory enduranceMuscular strength and power, agility and muscular enduranceImmediate physiological responses to trainingFactorImmediate physiological responseResistance TrainingRecovery PeriodHeart RateRises in anticipation of exerciseLinear increase until MHRPlateaus when steady state is reached during prolonged exerciseIncrease in HR as more repetitions are performedThe fitter you are, the quicker you recoverVentilation Rate(Depth and rate of breathing – breaths per minute)Rises in anticipation of exerciseSecond rise as rate and depth of breathing increasesRise corresponds with increased oxygen consumption and CO2 producedIncreases due to need to remove CO2 rather than the need for oxygenIncrease in ventilation rates as more repetitions are performedInitial decline followed by gradual return to normal statesStroke Volume(Amount of blood pumped from the left ventricle per beat)Increases during exerciseGreatest increase is from period of rest to moderate intensityPlateaus as exercise intensity increasesVirtually no change from resting levelsCardiac Output(Amount of blood pumped from the left ventricle per minute)Sharp increase as exercise commencesContinues as workload increases in order to meeting exercising muscles’ need for O2Lactate Levels(Concentration of lactic acid present in the blood, product by breakdown of carbs)Concentration increases as exercise increasesHigh intensity creates higher lactate levelsAccumulates when we exercise above the lactate inflection pointHigh levels of lactate make it difficult for muscle fibres to contractOnce maximal exercise ceases, lactate levels will begin to return to resting levelsExamine the reasons for the changing patterns of respiration and heart rate during and after submaximal physical activityHow do biomechanical principles influence movement?Biomechanics: Science concerned with forces and the effect of these forces on and within the human bodyChoose the best technique to achieve our best performance with consideration to body shapeReduces the risk of injury by improving the way we moveDesign and use equipment that contributes to improve performancesMotionThe application of linear motion, velocity, speed, acceleration, momentum in movement and performance contextsMotion: Movement of a body from one position to anotherLinear motion: When the body and all parts connected to it travel the same distance in the same direction and at the same speedEg. Skiing, swimming and sprint eventsAngular motion: Motion of an object about a fixed point or fixed axisMovements include: Rotating, spinning, swinging or rollingEg. Ballet, skateboarding and figure skatingVelocity: Displacement/TimeDisplacement: Movement of a body from one location to another in a particular directionSpeed: Distance/TimeAcceleration: Rate at which velocity changes in a given amount of timePositive acceleration: Increase in velocityNegative acceleration: Decrease in velocityMomentum: Quantity of motion that a body possessesMomentum = Mass x VelocityLinear Momentum: When moving bodies travel in a straight lineAngular Momentum: When moving bodies generate momentum that does not travel straightConservation of Momentum: Moment is always conserved in a close systemContraction and rebounds release heat and sound energyAlso pushes the ball forwardApply principles of motion to enhance performance through participation in practical workshopsExample: 100m sprintBody position at the start promotes forward thrust and increases power by placing the centre of gravity low in front of the torsoStarting blocks allow legs to be in a more efficient position to deliver thrustBody position after crossing the line promotes deceleration with a backward lean in a upright position. This causes the centre of gravity to return to within the body alignmentDeceleration occurs with more heel strike long stride lengthsBalance and stabilityCentre of gravityDefinition: Point at which all the weight is evenly distributed and about which the object is balancedIn the human body, position of centre of gravity depends on how body parts are arrangedVarying the centre of gravity in the execution of a skill can enhance performanceHigh jumping Fosbury flop technique Centre of gravity does need to clear the bar as it’s outside of the bodyScissor method Jumper must propel their entire body over the bar as the centre of gravity must clear the barLine of gravityDefinition: Imaginary vertical line passing through the centre of gravity; extends to the groundIndicates the direction that gravity is acting on the bodyMost stable: Line of gravity falls through the centre of the base of supportBase of supportDefinition: Imaginary base that surrounds the outside edge of the body when it’s in contact with a surfaceNarrow base: Small force is needed to make the person lose their balanceWide base: Essential for stabilityCloser the centre of gravity is to the base of support, the more stable the body isTogether, they provide stability and explosive power to change directions quicklyApply principles of balance and stability to enhance performance through participation in practical workshopsDescribe how balance and stability can be used to enhance performance. (4 Marks)To enhance performance, an individual can manipulate their centre of gravity and hence the line of gravity, as well as their base of support in order to best execute particular moves. For example, tennis players often lower their centre of gravity by bending forward and widen their base of support by standing with their feet apart in preparation to receive a fast serve. The wide base of support enhances their balance and stability and also enabled the centre of gravity to be moved in the desired direction more easily. Furthermore, the centre of gravity can be varied in the execution of a skill in order to enhance performance. For example, normally, our centre of gravity is in the middle of our body. Hence, a high jumper often employs the fosbury flop technique in contrast to the scissor method as their centre of gravity does not need to clear the bar while in the scissor method, the jumper must propel their entire body over the bar. As a result, balance and stability are crucial factors to consider to enhance skills and performance in sporting events. Describe how a gymnast applies the principles of balance and stability in performing a handstand. (6 Marks)The principles of balance and stability include the manipulation of the centre and line of gravity and also a person’s base of support. The centre of gravity is defined as the point at which all the weight of an individual is evenly distributed and about which the object is balanced while the line of gravity is an imaginary line that falls that through the centre of gravity and extends to the ground. The base of support is an imaginary base that surrounds the outside edge of the body when its contact with a surface. First of all, a wider base of support provides more stability and thus, a gymnast should spread their hands out further to maintain the handstand. Furthermore, gymnasts must have a high level of control over their centre of gravity by tightening their stomach, shoulders and hips in order to keep their body in a straight line. As a result, the line of gravity will fall directly through the centre of the gymnast’s body and thus fall directly in the centre of the base of support. This maximises stability and enables the gymnast to hold the handstand without falling over.If the gymnast arches due to the position of their legs, such as the legs arching past their head, it will cause the centre of gravity to shift outside of the body, leading to a loss of balance. This is also due to the action of gravity acting on the legs so it will pull the gymnast’s body down towards the ground. Therefore, this shows the importance of maintaining the centre of gravity within the body by widening the base of support. Fluid mechanicsFlotation, centre of buoyancyFloat: Buoyant force is greater than or equal to your weightBuoyancy: Upward force on the body experienced when immersed in waterCentre of buoyancy: Point where the amount of volume under the water is equally distributed on either sideKeeping as much of your body under water as possible will maximise the amount of water displaced; increases buoyant force and makes it easier to floatFluid resistanceDrag: Force generated by an object when it travels through a fluid mediumLift: Force generated by an object moving through fluid that is in opposition to the gravitational pull or weight of the objectTo improve resistance, make their bodies as smooth as possibleEg. Close-fitting swimwear or shaving the body and headEffective kick in freestyle helps to keep the body streamlined and reduce dragApply principles of fluid mechanics to enhance performance through participation in practical workshopsOutline how the dimpled design of golf ball surfaces allows greater distance to be achieved than by striking a smooth ballDimpled design enables it to trap ait at high velocities and thus create a smoother surfaceThis reduces drag by redirecting more air pressure behind the golf ball rather than in frontThis higher pressure at the back forces them to go a longer distanceSmooth balls do not allow this manipulation of pressure and thus do not go as farMagnus EffectRefers to the effect of rotation or spin on objects in motionThe effect explains why spinning objects (eg. golf balls) deviate from their normal flight pathsTopspin: Occurs when a ball or object rotates forward on its horizontal axis This causes it to drop sharplyBackspin: Occurs when a ball or object rotates backward This causes it to fall slowly at the end of flightDescribe how principles of fluid mechanics have influenced changes in movement and performance (eg. technique modification, clothing/suits, equipment/apparatus)Explain how improved techniques and materials have been employed to reduce both profile and surface drag in sporting activitiesSpecially designed suits and swimwear in swimming activities have helped to reduce both profile and surface drag; the suits are usually extremely tight, reducing cross-sectional sizeThe suits can also entrap fluid in its surface and thereby reduce friction by producing a water-on-water effect on dragStreamlined body position; avoid entering head too early, which increases dragArm stroke is curvilinear to allow pushing back on still water and this provides more thrustCyclists also minimise cross-sectional size by tightly crouching and using specialised handle bars to produce a shape that minimises dragBikes will less spokes also minimise dragDiscuss how knowledge of the principles of fluid mechanics has influenced changes in movement and performance. (5 Marks)Understanding fluid mechanics including fluid resistance, flotation and the centre of buoyancy have led to the introduction of various movements, techniques and equipment in order to enhance performance. For example, swimmers often wear specially designed swimwear including swimming caps to help reduce profile and surface drag. Since the swimwear is extremely tight and conforms to the swimmer’s body shape, this also helps to reduce cross-sectional size. Special suits in professional swimming can also entrap fluid in its surface and hence reduce friction and fluid resistance by producing a water-on-water effect on drag. Furthermore, understanding the principles of flotation and how the centre of buoyancy can be affected has led to the improvement of swimming techniques. For example, flotation arises when the buoyant force acting on the swimmer is greater than or equal to their weight. Hence, keeping as much of their body under water as possible during backstroke will increase the buoyant force, thus making it easier to float.Furthermore, the Magnus effect is a form of fluid resistance that comes into play in ball sports such as golf, tennis and cricket. This concept refers to the effect of rotation or spin on objects in motion and also helps to explain why spinning objects such as a cricket ball deviate from their normal paths. In the context of cricket, the cricket ball has both a shiny and a rough side, thus allow for the manipulation of air pressure to cause the ball to spin a particular way and deceive the opponent. When the ball is bowled, the rougher side experiences low pressure and high resistance. As a result, the ball will favour the low pressure and move in that direction. Through the understanding of fluid mechanics, sportsmen such as cricket bowlers have been able to enhance their skills and performance. ForceForce: Push or pull acting on an objectForce = Mass x AccelerationHow the body applies forceBody produces force primarily through the muscular system promoting movement of the skeletal systemBody is faced with opposing forces such as gravity, air resistance, water resistance and frictionInternal Force: Ones that develop within the body (eg. contraction of quadriceps when kicking)External Force: Comes from outside the body (eg. gravity)Applied Force: Generated by muscles working on jointsReaction Force: Equal and opposite forces exerted in response to applied forcesHow the body absorbs forceForce distributed over a large area has less impact than that applied to a smaller areaChanging the impact from direct to oblique will lessen the forceJoints bend or flex in response to the impact generated by the force- This helps to prevent injury to surrounding tissueApplying force to an objectGreater the force applied, the greater the speed and acceleration of that objectObjects of greater mass require more force to move them than objects of smaller massCentripetal force: Directed towards the centre of a rotating bodyCentrifugal force: Directed away from the centre of a rotating bodyApply principles of force to enhance performance through participation in practical workshopsIn the context of a team game, describe how the body applies and absorbs force. (6 Marks)Force itself is a push or pull acting on an object and a body primarily does this through the muscular system promoting movement of the skeletal system. In a game of cricket, there are three players to consider: the bowler, the batter and the fielders. According to Newton’s second law, force equals to mass times acceleration. Therefore, angular momentum generated by the run-up and the overarm action of the bowl results in greater acceleration of the ball. A consequence of this is a greater application of force to the cricket ball. This same idea can be applied to the batter as well. That is, as the batter swings his bat, he applies force through the momentum of the swing in order to hit the ball over a large distance. Furthermore, the absorption of force is most evident in the fielders including the wicket keeper, as they catch the accelerating ball. Following Newton’s first law of motion, the cricket ball will continue to remain in motion until an external force is applied to it. When a fielder catches a ball, they apply force to it in order to prevent it from staying in motion and the absorption of the remaining force due to the acceleration of the ball is done through flexion of the elbow and a carry through to the waist and thus, prevents injury of the hand. Furthermore, cricket pads will also absorb force by distributing the force over the area of the pad. ................
................

In order to avoid copyright disputes, this page is only a partial summary.

Google Online Preview   Download