PEShare.co.uk Shared Resource

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PEShare.co.uk Shared Resource

  1. 1. <ul><li>AQA Examinations AS / A Level Sport and Physical Education AS 5581 A 6581 </li></ul><ul><li>Module 1 </li></ul><ul><li>Part B </li></ul><ul><li>Physiological Factors which Improve Performance </li></ul>
  2. 2. There are three ways to measure heart performance in sport and exercise: Heart Rate 64 beats per minute is a typical result for a fit person at rest. The total amount of blood pumped out of the heart in one beat . Definitions of Heart Function The number of times the heart beats per minute . Stroke Volume <ul><li>Heart Rate </li></ul><ul><li>Stroke Volume </li></ul><ul><li>Cardiac Output </li></ul>
  3. 3. Cardiac output <ul><li>Cardiac output </li></ul><ul><ul><li>volume of blood ejected by left or right ventricle per minute </li></ul></ul><ul><ul><ul><li>Q = stroke volume (mL/beat) x heart rate (beats/min) </li></ul></ul></ul><ul><ul><ul><ul><li>Average Q approx 5.25 L/min (70 mL/beat x 75 beats/min) </li></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Similar to total blood volume of ~5 litres (male) </li></ul></ul></ul></ul></ul><ul><li>Cardiac reserve </li></ul><ul><ul><li>maximal Q – resting Q </li></ul></ul>
  4. 4. Stroke volume <ul><li>Stroke volume (SV) </li></ul><ul><ul><li>volume of blood ejected by a ventricle during systole </li></ul></ul><ul><ul><ul><li>depends on: </li></ul></ul></ul><ul><ul><ul><ul><li>Preload </li></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Degree of stretch prior to contraction </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><li>Contractility </li></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Forcefulness of contraction </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><li>Afterload </li></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Pressure that must be exceeded before ejection of blood from ventricles can occur </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>(Starlings Law) </li></ul></ul></ul></ul></ul>
  5. 5. For example… Stroke Volume = 75 ml Heart Rate = 65 b.p.m. Cardiac Output = 75 x 65 = 4875 ml Stroke Volume = 150 ml Heart Rate = 200 b.p.m. Cardiac Output = 150 x 200 = 30000 ml Cardiac Output At rest… While exercising… Cardiac output is… … the total output of blood from the heart in one minute . It is calculated using the formula… Cardiac Output = Stroke Volume x Heart Rate
  6. 6. HEART DYNAMICS <ul><li>AVERAGE RESTING HEART RATE VALUES </li></ul><ul><li>MALES - 70 bpm </li></ul><ul><li>FEMALES - 72 bpm </li></ul><ul><li>CARDIAC OUTPUT </li></ul>The Resting Heart <ul><li>= SV x HR (this is the formula used for each calculation) </li></ul><ul><li>SV = stroke volume - measured in ml (cm 3 ) </li></ul><ul><li>AT REST </li></ul><ul><li>untrained person endurance athlete </li></ul><ul><li>= 75 (ml) x 70 (bpm) = 109 (ml) x 48 (bpm) </li></ul><ul><li>= 5.25 l min -1 = 5.23 l min -1 </li></ul><ul><ul><li>(or dm 3 min -1 ) </li></ul></ul><ul><li>DURING MAXIMAL EXERCISE </li></ul><ul><li>untrained person endurance athlete </li></ul><ul><li>= 120 (ml) x 200 (bpm) = 190 (ml) x 200 (bpm) </li></ul><ul><li>= 24 l min -1 = 38 l min -1 </li></ul>
  7. 7. FACTORS REGULATING THE HEART <ul><li>NEURAL </li></ul><ul><li>NERVES FROM THE CARDIAC CONTROL CENTRE (CCC) </li></ul><ul><li>RECEPTORS </li></ul><ul><li>provide sensory information to CCC used in regulation of HR and SV </li></ul><ul><li>proprioceptors located in muscles / joints </li></ul><ul><ul><li>detect muscle stretching and joint angles changing </li></ul></ul><ul><li>central and peripheral chemoreceptors </li></ul><ul><ul><li>detect changes in blood pH (H + ion concentration), O 2 , CO 2 , K + levels </li></ul></ul><ul><li>baroreceptors in aorta and carotid arteries </li></ul><ul><ul><li>detect changes in blood pressure </li></ul></ul>Heart Rate Response to Exercise
  8. 8. FACTORS REGULATING THE HEART <ul><li>HORMONAL </li></ul><ul><li>ADRENALINE (fright - flight - fight) </li></ul><ul><li>stimulates HR by GLYCOGENOLYSIS (the conversion of glycogen to glucose - a rapid process) </li></ul><ul><li>and breakdown of fats and proteins ( slow ) </li></ul><ul><li>these processes release energy </li></ul><ul><li>NOREPINEPHRINE </li></ul><ul><li>this is a form of adrenaline released by the sympathetic neurones acting directly on the pacemaker </li></ul><ul><li>increases HR and SV </li></ul><ul><li>INTRINSIC </li></ul><ul><li>increased TEMPERATURE of myocardial tissue </li></ul><ul><li>increased VENOUS RETURN </li></ul><ul><ul><li>stimulates SA node and hence HR </li></ul></ul><ul><ul><li>Starling’s Law of the heart </li></ul></ul>Heart Rate Response to Exercise <ul><li>OTHER FACTORS </li></ul><ul><li>AGE </li></ul><ul><li>GENDER </li></ul><ul><li>POSITION OF BODY </li></ul><ul><li>EXERCISE </li></ul><ul><li>STATE OF HEALTH </li></ul>
  9. 9. Regulators of the Heart: Factors Influencing Stroke Volume
  10. 10. Distribution of blood flow (Q) during rest and heavy exercise
  11. 11. SHORT-TERM EFFECTS OF EXERCISE ON THE HEART <ul><li>INTERPRETATION OF GRAPH </li></ul>Heart Rate Response to Exercise <ul><li>a - anticipatory rise due to hormonal actions of adrenaline and norepinephrine </li></ul><ul><li>b - sharp rise , mainly anaerobic work </li></ul><ul><ul><li>due to proprioceptor / sensory stimulation </li></ul></ul><ul><ul><li>continued release of hormones </li></ul></ul><ul><ul><li>and action of muscle pump </li></ul></ul><ul><li>c - continued high HR due to maximal work loads which continue to stress anaerobic systems </li></ul><ul><ul><li>producing lactic acid (H + ) + CO 2 + K + which stimulate chemoreceptors </li></ul></ul><ul><ul><li>intrinsic factors are also stimulated at maximal level </li></ul></ul><ul><li>d - steady state and some recovery of O 2 debt </li></ul><ul><li>e - rapid recovery due to cessation of proprioceptive stimuli / muscle pump / withdrawal of hormones, fast recovery of PC stores </li></ul><ul><li>f - slow recovery , clearance of metabolites (like lactic acid) </li></ul><ul><ul><li>heat loss hence muscle cooling </li></ul></ul><ul><ul><li>general body systems returning to pre-exercise levels </li></ul></ul>
  12. 12. SHORT-TERM EFFECTS OF EXERCISE ON THE HEART Heart Rate Response to Exercise <ul><li>DIFFERENCES BETWEEN INDIVIDUALS </li></ul><ul><li>patterns of recovery vary </li></ul><ul><li>gender </li></ul><ul><li>state of health </li></ul><ul><li>values of max HR vary according to formula : </li></ul><ul><li>HRmax = 220 - age approximately </li></ul>
  13. 13. LONG-TERM EFFECTS OF EXERCISE ON THE HEART Most studies use data taken from male subjects. Values for females may differ When CV improvements are made and efficiency is increased, Q could be higher to compensate for the reduction to the HR. However as the SV will have increased through training the increase in Q may be small 140 ml Av. 70 ml Stroke volume 20 – 25 l/min Av. 5 l/min Cardiac output (Q) Max. 22-0 – age in years Av. 72 bpm Heart rate During exercise At rest

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