2.1 Cardiovascular System and Exercise

The cardiovascular system plays a crucial role in exercise, adapting to meet increased demands. During workouts, your heart rate spikes, pumping more blood to active muscles. This boosts oxygen delivery and helps remove waste products.

Over time, regular exercise leads to lasting changes in your heart and blood vessels. Your heart gets stronger, pumping more efficiently. Blood volume increases, and resting heart rate drops. These adaptations improve your overall fitness and health.

Cardiovascular Adaptations to Exercise

Acute Adaptations

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• Increased heart rate to meet the increased oxygen and nutrient demands of active muscles
• Increased stroke volume to deliver more blood per contraction
• Increased cardiac output as a result of elevated heart rate and stroke volume
• Redistribution of blood flow to active muscles through vasodilation of supplying blood vessels

Chronic Adaptations

• Cardiac hypertrophy: increased size and strength of the heart muscle
• Improved myocardial contractility enabling the heart to pump more efficiently
• Enhanced coronary circulation to better supply the heart muscle with oxygen and nutrients
• Increased total blood volume enhancing oxygen delivery to working muscles and improving thermoregulation
• Decreased resting heart rate (bradycardia) due to increased vagal tone and more efficient cardiac function
• Enhanced capillarization in skeletal muscles allowing for better oxygen and nutrient exchange between the bloodstream and muscle fibers

Oxygen Delivery During Exercise

Cardiovascular System's Role

• Transports oxygenated blood from the lungs to the working muscles
• Transports deoxygenated blood back to the lungs for reoxygenation
• Increases blood flow to active muscles through vasodilation of supplying blood vessels
• Decreases blood flow to less active tissues through vasoconstriction
• Increases cardiac output to ensure adequate oxygen and nutrient supply to working muscles

Waste Product Removal

• Removes metabolic waste products such as carbon dioxide and lactic acid from active muscles
• Transports waste products to the lungs (carbon dioxide) and liver (lactic acid) for elimination or recycling
• Helps maintain acid-base balance in the body during exercise

Exercise Intensity vs Cardiovascular Function

Proportional Relationship

• As exercise intensity increases, heart rate proportionally increases to meet higher metabolic demands
• Stroke volume also increases with exercise intensity, contributing to higher cardiac output
• The linear relationship between exercise intensity and heart rate is known as the heart rate-workload relationship

Cardiovascular Limitations

• At higher exercise intensities, the cardiovascular system reaches its maximum capacity to deliver oxygen to the muscles
• This leads to a plateau in oxygen uptake (VO2max), which is a key determinant of endurance performance
• The cardiovascular system's ability to maintain high levels of cardiac output during prolonged exercise is crucial for endurance

Blood Flow Distribution

• As exercise intensity increases, a greater proportion of cardiac output is directed to the working muscles
• This redistribution of blood flow ensures that active muscles receive adequate oxygen and nutrients
• Blood flow to less active tissues, such as the digestive system, is reduced during high-intensity exercise

Health Benefits of Regular Exercise

Cardiovascular Fitness

• Improves the ability of the heart, lungs, and blood vessels to supply oxygen to the muscles during sustained physical activity
• Enhances the cardiovascular system's efficiency in delivering oxygen to the muscles
• Reduces fatigue during daily activities and improves overall aerobic capacity

Blood Pressure and Lipid Profile

• Reduces resting blood pressure in individuals with hypertension, lowering the risk of cardiovascular disease and stroke
• Improves blood lipid profiles by increasing high-density lipoprotein (HDL) cholesterol and decreasing low-density lipoprotein (LDL) cholesterol and triglycerides
• Helps maintain healthy blood vessel function and reduces the risk of atherosclerosis

Myocardial Function

• Improves myocardial contractility, allowing the heart to pump more blood with each contraction
• Enhances the heart's ability to respond to increased demands during exercise
• Promotes a more efficient heart that can maintain higher cardiac output for longer periods