Acute Responses To Exercise

• Acute responses are the body’s immediate, short-term responses that last only for the duration of the training or exercise session and for a short time period (recovery) afterwards
• Acute responses involve the respiratory, cardiovascular, and muscular systems working together to supply more energy/ATP to working muscles and to remove waste products
• At the start of exercise, changes within the respiratory system aim to increase the volume of oxygen intake at the lungs, which is then transported to and utilized by the body
• Ventilation increases rapidly at the start of sub-maximal intensity exercise and then more slowly until it reaches a plateau (4 to 5 minutes into exercise)
• At maximal intensity, ventilation increases until exercise is stopped
• Increased gaseous exchange/diffusion involves gases like oxygen and carbon dioxide moving from areas of high pressure to low pressure, facilitating oxygen intake by the muscles and removal of carbon dioxide
• Increased oxygen uptake during exercise is due to the working muscles requiring more oxygen for ATP resynthesis, with a linear relationship between oxygen uptake and exercise intensity
• Factors affecting VO2 Max include body size, gender, genetics, age, and training status
• Cardiovascular system responses during exercise aim to increase the volume of oxygenated blood delivered to the working muscles, as well as speed up the removal of carbon dioxide and waste products
• Cardiovascular responses during exercise include:

  • Increased Heart Rate (HR): number of heart beats per minute, aiming to increase the volume of oxygenated blood transported around the body for muscle utilization
  • Increased Stroke Volume (SV): amount of blood ejected from the left ventricle with each heart contraction
  • Increased Cardiac Output (Q): total amount of blood ejected from the left ventricle per minute
  • Increased Systolic Blood Pressure: pressure exerted by the blood against arterial walls when the heart contracts
• During exercise, there is a redistribution of blood flow, altering the percentage of cardiac output distributed to various body sites, with increased venous return and arteriovenous oxygen difference (A-VO2 diff)
• When exercise begins, there is an increase in venous return, assisted by valves and the "muscle pump"
• Increased Arteriovenous Oxygen Difference (A-VO2 diff) is a measure of the difference in oxygen concentration between arterial and venous blood
• During exercise, muscles uptake more oxygen, leading to a change in oxygen concentration in venous blood compared to arterial blood, resulting in an increase in the a-vO2 difference
• Decreased Blood Volume is caused by the regulation of body temperature through releasing heat in the form of sweat, reducing the overall volume of blood in the system and inhibiting blood flow
• Blood pressure is the pressure exerted by the blood against the arterial walls as it is forced through the circulatory system by the action of the heart, with systolic and diastolic components
• Heart Rate has a strong relationship with exercise intensity and is affected by variables like fatigue level, hydration status, ambient temperature, altitude, and illness
• Stroke Volume is the amount of blood pumped out of the left ventricle per beat, increasing with exercise intensity up to a point and remaining essentially unchanged thereafter
• Blood pressure increases with an increase in cardiac output, affecting systolic pressure more during exercise using large muscle groups
• During exercise, blood flow is redistributed to meet the demands of active muscles, achieved by vasodilation in working muscles and vasoconstriction in organs
• Cardiovascular responses aim to get more blood, oxygen, and fuels to working muscles and speed up the removal of wastes
• Cardiac Output increases to meet the demand for blood flow to deliver oxygen and nutrients to working muscles and remove waste products
• Muscular responses to exercise include increased motor unit recruitment, muscle temperature, oxygen uptake and consumption, metabolic by-products, and decreased energy substrate stores