Acute exercise Acute exercise –Single bout of exercise  Steady State (Submaximal) exercise  Maximal exercise Chronic exercise Chronic exercise –Months of conditioning or training –Differences between training and untrained individuals EXERCISE AND THE HEART

Cardiovascular Response to Acute Exercise  Blood flow (and distribution)….  All of the above change during exercise in order to meet the increase O2 and energy demands of the muscles.  Heart rate (HR), stroke volume (SV), and cardiac output (Q)....  Blood pressure …

Heart Rate and Acute Exercise Why does heart rate increase during acute exercise? Why does heart rate increase during acute exercise? What causes heart rate exercise? What causes heart rate exercise? Why does heart rate level off when the exercise intensity levels off? Why does heart rate level off when the exercise intensity levels off? What is the relationship between heart and exercise intensity? What is the relationship between heart and exercise intensity? How is maximum heart rate estimated? How is maximum heart rate estimated?

Heart Rate Mile Heart Rate and Acute Exercise

What causes heart rate to increase? What causes heart rate to increase? Parasympathetic Parasympathetic Sympathetic Sympathetic Catecholamines Catecholamines –Epinephrine –Norepinephrine

Heart Rate and Acute Exercise Why does heart rate level off when the exercise intensity levels off? Why does heart rate level off when the exercise intensity levels off? O2 supply = O2 demand O2 supply = O2 demand

Heart Rate and Acute Exercise

Heart Rate and Acute Maximal Exercise What is the relationship between heart rate and exercise intensity? Or, how is heart affected by the intensity of exercise?

Heart Rate and Acute Maximal Exercise Can be estimated: HRmax = 220 – age in years Can be estimated: HRmax = 220 – age in years –For 20 year old, HRmax = 200 –For 43 year old, HRmax = 177 Other formulas: Other formulas: 210 – (0.65 x age) 210 – (0.65 x age) 208 – (0.70 x age) 208 – (0.70 x age) –For 20 year old, HRmax = 194 –For 43 year old, HRmax = – (0.72 x age) 202 – (0.72 x age)

Stroke Volume and Acute Exercise  Why does stroke volume increase during exercise?  What causes stroke volume to increase during exercise?  Why does stroke volume stop increasing, or reach its maximum, before a person reaches their maximal effort?  What is cardiovascular drift?

Stroke Volume and Acute Exercise What causes stroke volume to increase during exercise? Hint: There is less residual volume What causes stroke volume to increase during exercise? Hint: There is less residual volume What is residual volume?What is residual volume? The amount of blood remaining in the heart after a contraction. Also called end systolic volumeThe amount of blood remaining in the heart after a contraction. Also called end systolic volume What causes the heart to beat stronger (and thus reduce the residual volume) during acute exercise? What causes the heart to beat stronger (and thus reduce the residual volume) during acute exercise? Increase sympathetic stimulation and increases in epinephrine and norepinephrine Increase sympathetic stimulation and increases in epinephrine and norepinephrine

Stroke Volume and Acute Maximal Exercise Why does stroke volume stop increasing, or reach its maximum, before a person reaches their maximal effort?

Stroke Volume and Acute Exercise What is cardiovascular drift? What is cardiovascular drift? What happens to the amount of plasma as exercise continues? Increase or decrease? What happens to the amount of plasma as exercise continues? Increase or decrease? What affect would a decrease in plasma volume have on stroke volume? What affect would a decrease in plasma volume have on stroke volume? If stroke volume decreases, what would have to happen to heart rate in order to keep blood flow or cardiac output at the same level? (see next slide) If stroke volume decreases, what would have to happen to heart rate in order to keep blood flow or cardiac output at the same level? (see next slide)

Stroke Volume and Acute Exercise Cardiovascular Drift

Cardiac Output and Acute Exercise If heart rate and stroke volume increase during exercise, what will happen to cardiac output? If heart rate and stroke volume increase during exercise, what will happen to cardiac output? Why is it important that cardiac output increases during exercise? Why is it important that cardiac output increases during exercise? How can even more blood be sent to the exercising muscles? How can even more blood be sent to the exercising muscles?

Cardiac Output and Acute Maximal Exercise If heart rate and stroke volume increase during exercise, what will happen to cardiac output? Why is it important that cardiac output increases during exercise?

Summary of HR, SV and Q During Acute Exercise Resting (supine) Resting (standing and sitting) Running Cycling Swimming Heart rateStroke volumeCardiac output Activity(beats/min)(ml/beat)(L/min)

Blood Flow and Acute Exercise How can even more blood be sent to the exercising muscles?. How can even more blood be sent to the exercising muscles?.

Blood Flow and Acute Exercise

How can even more blood be sent to the exercising muscles? How can even more blood be sent to the exercising muscles? Vasodilation of arterioles near exercising muscles Vasodilation of arterioles near exercising muscles –Waste products Vasoconstriction of arterioles near non- exercising muscles and organs. Vasoconstriction of arterioles near non- exercising muscles and organs. –Sympathetic stimulation

Blood Pressure During Acute Exercise How would an increase in blood flow through the blood vessels affect blood pressure? How would an increase in blood flow through the blood vessels affect blood pressure? How would vasodilation of the blood vessels affect blood pressure? How would vasodilation of the blood vessels affect blood pressure?

Blood Pressure During Acute Exercise Cardiovascular Endurance Exercise What affect does CV exercise have on systolic blood pressure? What affect does CV exercise have on systolic blood pressure? Why? Why? What affect does CV exercise have on diastolic blood pressure? What affect does CV exercise have on diastolic blood pressure? Why? Why?

Blood Pressure During Acute Exercise Resistance Exercise How does resistance exercise affect blood pressure? How does resistance exercise affect blood pressure? Why? Why? Some BP increases are attributed to the Valsalva maneuver Some BP increases are attributed to the Valsalva maneuver

Blood Pressure During Acute Exercise

Blood Flow and Acute Exercise What is responsible for the increase blood flow to the muscles during exercise? What is responsible for the increase blood flow to the muscles during exercise? –Increased cardiac output  Increased heart rate and stroke volume –Redistribution of blood flow  Vasodilation and vasoconstriction What will happen to aerobic energy production as more blood is supplied to the muscles during exercise What will happen to aerobic energy production as more blood is supplied to the muscles during exercise How is aerobic energy production measured? How is aerobic energy production measured? Oxygen consumption or VO2 Oxygen consumption or VO2

Oxygen Consumption VO2 is a measure of how much and how fast O2 is used to make energy (ATP) VO2 is a measure of how much and how fast O2 is used to make energy (ATP) In order for VO2 to increase what must change inside the body? In order for VO2 to increase what must change inside the body? 1. Increase cardiac output 2. Increase extraction of oxygen from the blood Therefore VO2 = cardiac output x the amount of oxygen extracted from the blood Therefore VO2 = cardiac output x the amount of oxygen extracted from the blood

Oxygen Consumption Oxygen Extraction at Rest Oxygen Extraction at Rest Arteries Arteries –20 ml or oxygen in every 100 ml of arterial blood Veins Veins –15 ml/100 ml of blood. How much oxygen did the muscles use? How much oxygen did the muscles use? This amount is call the a-vO2 difference. This amount is call the a-vO2 difference.

Oxygen Consumption Cardiac output (Q) = how quickly an amount of blood (e.g. 100 ml) flows to the muscles Cardiac output (Q) = how quickly an amount of blood (e.g. 100 ml) flows to the muscles a-v O2 difference = amount oxygen of that 100 ml is extracted (or removed) from the blood a-v O2 difference = amount oxygen of that 100 ml is extracted (or removed) from the blood VO2 = Q x a-v O2 difference VO2 = Q x a-v O2 difference VO2 is how aerobic energy production is measured VO2 is how aerobic energy production is measured

Oxygen Consumption What does VO2 tell us? What does VO2 tell us? How much oxygen is being used to make energy How much oxygen is being used to make energy Resting VO2 = 3.5 ml/kg/min Resting VO2 = 3.5 ml/kg/min Exercise VO2 Exercise VO2 Maximal VO2 (VO2 max) Maximal VO2 (VO2 max)

Exercise VO2 Jogging = 24 ml/kg/min Walking = 16 ml/kg/min Running = 38 ml/kg/min Sprinting = 57 ml/kg/min VO2 (ml/kg/min) Time

Maximal VO2 Results from a graded treadmill test where treadmill speed and elevation are increased every minute.

Maximal VO2 Values PERCENTILE Men Women ►Average values for year olds: 44 to 50 ml · kg -1 · min -1 for males and 38 to 42 ml · kg -1 · min -1 for females