Cardiovascular response to exercise
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Cardiovascular response to exercise

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    Cardiovascular response to exercise Cardiovascular response to exercise Presentation Transcript

    • Homework – due Thursday 12 th Jan
      • Complete Progress Test 2 . Use your notes and book to help you so that you score 35 out of 35 when I mark them.
      • Do not just copy sentences you must make sure you have a thorough understanding of each answer and come to ask me if you are unsure
        • My free periods...
          • Tuesday 2
          • Wednesday 1&2
          • Friday 3
          • Monday or Friday period 4 (lower school lunch)
    • Slow Twitch (Type 1) Fast Oxidative Glycolytic (Type 2a/FOG) Fast Glycolytic (Type 2b/FG) Structural Characteristics Colour Size Small Large Large No. of mitochondria Large Moderate Small No. of capillaries Large Moderate Small Myoglobin concentration High Moderate Low Phosphocreatine (PC) stores Low High High Glycogen stores Low High High Triglyceride (TG) stores High Moderate Low Functional Characteristics Speed of contraction Slow Fast Fastest Force of contraction Low High Highest Fatigue resistance High Low Lowest Aerobic capacity High Low Lowest Anaerobic capacity Low High Highest Best suited activity 100m, shot put, long jump 1500m Marathan, 10K
    • Effects on skeletal muscle Effects of warm up Effects of a cool down
      • Increase in muscle/core body temperature
      • = reduction in muscle viscosity , leading to improvement in the efficiency of muscular contraction
      • = a greater speed and force of contraction due to a higher speed of nerve transmission
      • = an increased elasticity that reduces the risk of injury due to increased extensibility of tendons and ligaments
      • = improved co-ordination between antagonistic pairs
      • Keeps the capillaries dilated, allowing oxygen rich blood to flush through the muscles
      • = an increase in the speed of lactic acid and carbon dioxide removal
      • = reduce acidity level
      • = reduced stimulation of pain receptors
      • Decreased risk of DOMS ( delayed onset of muscle pain and soreness ) experienced 24-48 hours after intense exercise due to microscopic tears in muscle fibres
    • Cardiovascular response to exercise Heart rate, stroke volume and cardiac output
    • Learning objectives
      • Be able to:
      • Provide definitions and resting values for SV, HR and Q.
      • Describe and explain changes in HR, SV and Q during maximal and sub maximal activity.
    • Resting values:
      • Complete a table to show the average resting values of HR , SV and Q in both an untrained and trained person
      Heart Rate (bpm) Stroke Volume (mls/beat) Cardiac Output (L/min) Average (Untrained) Trained
    • Heart rate (HR) at rest The number of ventricular contractions of the heart in one minute
    • Measuring heart rate (HR)
      • Can measure carotid (neck) pulse or radial (wrist) pulse
      • Measure and record your HR in beats per minute (bpm) in the following situations
        • Standing
        • Sitting
        • Lying down (supine)
      • Describe the changes in HR due to changes in position. Suggest reasons why.
      • Compare HR values between members of the group. What could account for these differences?
    • Heart rate (HR) at rest Average resting HR = 70-72 bpm Low resting HR indicates high aerobic fitness Resting heart rate below 60 is termed bradycardia Bradycardia caused by ‘hypertrophy’ which is an increase in size and strength of cardiac (heart) muscle wall Maximal heart rate = 220 - Age
    • Stroke volume (SV) at rest The volume of blood ejected from the heart ventricles each contraction
    •  
    • Stroke volume (SV) at rest The volume of blood ejected from the heart ventricles each contraction The difference in the volume of blood in the ventricle blood before and after ventricle contraction. SV = EDV – ESV SV = End Diastolic Volume – End Systolic Volume Average volume at rest = 70mls per beat
      • What does the calculation below tell you?
      Heart rate (beats per minute) Stroke volume (ml per beat) X 70 70 X ? = = Cardiac output (mls/min) = 4.9 L/min = 4900 mls/min
    • Cardiac Output (Q)
      • The volume of blood ejected by the heart ventricles in one minute
      Q = SV X HR
    • Q = SV X HR
      • If an athlete has a resting Q of 5L/min, but a resting HR of 60, what is their resting SV?
      • Suggest reasons to explain why SV has increased.
      SV = Q / HR = 5 / 60 = 0.08333 L/beat = 83.3 ml/beat SV = Q / HR = (5 x 1000) / 60 = 5000 / 60 = 83.3 ml/beat
    • Describe the relationship between stroke volume, heart rate and cardiac output and resting values for each Cardiac Output = Stroke Volume x Heart Rate = 70ml x 70bpm = 4900ml per minute = 4.9 (5) Litres per minute AT REST MAX EXERCISE Stroke Volume = 120 ml (untrained) 160ml (trained) Cardiac Output = 20-40 L/min Heart rate = 220 – Age
    • Resting values: Trained v Untrained
      • Complete a table to show the average resting values of HR , SV and Q in both an untrained and trained person
      • Suggest reasons for the changes seen in trained athletes
      70bpm 50bpm 70-72 ml 100ml 5L (5000ml) 5L (5000ml) Heart Rate (bpm) Stroke Volume (mls/beat) Cardiac Output (L/min) Average (Untrained) Trained
    • Learning objectives
      • Be able to:
      • Provide definitions and resting values for SV, HR and Q.
      • Describe and explain changes in HR, SV and Q during maximal and sub maximal activity.
    • Cardiovascular response to exercise
      • During exercise....
      • Increased oxygen consumption as there is an increased demand for oxygen for aerobic respiration to produce energy
      • In response...
      • Heart rate increases
      • Heart contracts more forcefully
      • causing stroke volume to increase
      Q = SV X HR Causes an overall increase in cardiac output
    • CV response to exercise
      • The hearts response to exercise must be considered during both submaximal and maximal exercise
      • Sub maximal exercise
        • Exercise performed at an intensity below an athlete’s maximal aerobic capacity or maximum VO 2 (oxygen capacity)
      • Maximal exercise
        • Exercise performed at an athlete’s maximum aerobic capacity or VO 2 max
      VO 2 max is the measure of the peak volume of oxygen (VO 2 ) you can consume and use in a minute.
    • HR response to exercise Work Recovery Prior Heart rate (bpm) 72 155 200 Maximal exercise Sub maximal exercise
    • HR response to exercise
      • Describe the sub maximal and maximal HR response prior to, during and in the recovery from exercise.
      • Include:
        • Reasons for anticipatory rise in HR
        • Differences between the values reached in sub maximal and maximal exercise
        • Words such as rapidly , gradual, decrease, increase, plateau, exercise intensity, oxygen debt
    • SV response to exercise
      • SV = EDV – ESV
      • Rest
        • SV = 130ml – 60ml
        • = 70ml
        • 70ml pumped to body and 60ml left in ventricles in reserve
      • Exercise
        • SV = 130ml – 10ml
        • = 120ml
        • 120ml pumped to the body and only 10ml in ventricles in reserve.
    • Stroke Volume Response to Exercise Exercise Intensity Stroke Volume (mls/beat) 150 50 100 Stroke volume increases linearly as exercise intensity increases but only up to 40 – 60 % of maximal intensity. After this point, SV values reaches a plateau Maximal SV values are reached during sub-maximal exercise
    • Stroke Volume response to Exercise
      • Stroke Volume increases due to:
      • Increased capacity of the heart to fill
        • Increased Venous Return (blood returning to the heart)
        • = Stretching of ventricular walls
        • = Increases filling capacity
        • = Increased End-Diastolic Volume (EDV)
        • = Increased Stroke Volume
      • Increased capacity of the heart to empty
        • Greater EDV = greater stretch of ventricular walls
        • = Increased force of ventricular contraction (ventricular systole)
        • = Increased contractility causes heart to almost completely empty
        • = increased Stroke Volume
    • SV response to exercise
      • SV reaches its maximal value at 40-60% of maximal exercise intensity (sub maximal intensity)
      • As exercise intensity increases towards maximal, cardiac output (Q) still needs to be increased to meet oxygen demand
      • What happens to allow Q to keep increasing so that an athlete can work maximally?
    • Cardiac Output Response to Exercise Work Recovery Prior Maximal exercise Sub maximal exercise Cardiac Output (Litres/minute) 20 5 10
    • 15-20 5 20-40 Q L/min KEY SUB-MAXIMAL EXERCISE MAXIMAL EXERCISE REST EXERCISE RECOVERY Q response to exercise
      • Increase prior to exercise due to adrenaline acting upon the sino-atrial node which increases HR (anticipatory response)
      • Increases directly in line with exercise intensity in order to meet the demand for oxygen from the working muscles
      • Plateau’s when Q meets O 2 demand in steady state exercise
      • Sudden decrease when exercise stops
      • Gradual decrease towards resting but still elevating above resting as need to repay the oxygen debt
    • Resting, sub maximal and maximal values
      • Create a table to show the resting, sub maximal and maximal values of
        • Heat rate (HR)
        • Stroke volume (SV)
        • Cardiac output (Q)
    • Example values Exercise Intensity Resting Sub-maximal (moderate intensity exercise) Maximal (high intensity exercise) SV 70ml HR 70-72bpm Q 5L/min
    • Example values Exercise Intensity Resting Sub-maximal (moderate intensity exercise) Maximal (high intensity exercise) SV 70ml 80-100ml untrained 160-200ml trained 100-120ml untrained 160-200ml trained HR 70/72bpm 100-130bpm 220 - age Q 5L/min Up to 10L/min 20-40L/min
    • Cardiovascular Drift
      • Cardiovascular drift (CVD, CV drift ) it is characterised by decrease in stroke volume and a parallel increase in heart rate
      • It is influenced by many factors, most notably the ambient temperature , hydration and the amount of muscle tissue activated during exercise.
      • To promote cooling, blood flow to the skin is increased .
      • This results in a decrease in pulmonary arterial pressure and reduced stroke volume in the heart. To maintain cardiac output at reduced pressure, the heart rate must be increased .
    • Heart and a healthy lifestyle
      • What is the heart’s main adaptation to sustained involvement in physical activity?
      • Hypertrophy = increase SV
      • = decreased resting HR
      • Increased potential to supply oxygen
      • Bradycardia = heart under less strain at rest
      • = over life time could slow down deterioration of heart
      • = improved quality of life
    • Learning objectives
      • Be able to:
      • Provide definitions and resting values for SV, HR and Q.
      • Describe and explain changes in HR, SV and Q during maximal and sub maximal activity.
    • Summary
      • At the onset of exercise cardiac output is increased by an increase in …………………………………………………..
      • When exercise intensity exceeds ……………………….. of an athlete’s maximal exercise intensity, stroke volume begins to ………………………..
      • Any further increase in cardiac output is a result of …………………………………………………………..
      heart rate and stroke volume 40 – 60% plateau an increase in heart rate
    • Exam question Draw a graph to show how the cyclist’s cardiac output changes in the following phases of the aerobic training session. • Prior to Exercise • Exercise Session • Recovery Period
    • Mark scheme
      • Resting value 5L/min approx (4-6L/min)
      • Anticipatory rise before exercise due to adrenaline release stimulating the SA node
      • Sharp increase
      • Plateau between 10-20L/min
      • Initial sharp decline with slow decline towards resting level
    • May 2011
      • The volume of blood pumped around the body by the heart varies according to the intensity of exercise performed
        • Define stroke volume and give a resting value for the average adult
        • Describe the changes that take place to stroke volume from rest to maximal exercise levels
    • Homework – due Thursday 12 th Jan
      • Complete Progress Test 2 . Use your notes and book to help you so that you score 35 out of 35 when I mark them.
      • Do not just copy sentences you must make sure you have a thorough understanding of each answer and come to ask me if you are unsure
        • My free periods...
          • Tuesday 2
          • Wednesday 1&2
          • Friday 3
          • Monday or Friday period 4 (lower school lunch)