Cardiovascular System Responses

• Cardiac cycle response to increased exercise intensity

  1. Heart rate increases

  2. Amount of blood filling atria and ventricles increases

  3. Systolic blood pressure rises

  4. Blood diverted to working muscles
• Anticipatory heart rate increase

  1. Occurs before start of exercise

  2. Caused by neurotransmitters like adrenaline and noradrenaline released from brain

  3. Anticipates what is going to happen and increases heart rate and blood flow to supply oxygen and nutrients to muscles
• Heart rate


  Increases according to body need, from around 75 BPM at rest to up to 200 BPM during exercise
• Reduced heart rate of trained athlete allows for greater filling during the longer diastole (relaxation) phase, leading to increased stroke volume
• Blood pressure


  Measure of arterial pressure exerted on blood vessel walls
• Systolic pressure


  Upper blood pressure value, during heart contraction phase
• Diastolic pressure


  Lower blood pressure value, during heart relaxation phase
• Average blood pressure is considered prehypertension if systolic is 120-139 or diastolic is 80-89, and hypertensive if 140/90 or more
• pH

  Measure of acidity or alkalinity, 7 is neutral, above 7 is alkaline, below 7 is acidic
• During exercise, pH can drop below 7 due to waste products like carbon dioxide and lactic acid in the blood
• Exercise increases this difference as working muscles demand more oxygen from arterial blood, decreasing oxygen content of venous blood
• Arterial blood


  Bright red due to high oxygen content