Acute Responses to Exercise Flashcards
Acute response
The body’s immediate and short term response to exercise. Lasts for the duration of exercise or training and while returning to pre exercise levels (recovery)
3 systems
Respiratory
Cardiovascular
Muscular
Acute cardiovascular responses to exercise
Increased heart rate, Increased stroke volume, Increased cardiac volume, Increased systolic blood pressure, Redistribution of blood flow, Increased venous return and Increased AVO2 difference
Increased heart rate
Number of times the heart contracts or beats per minute. An increase in heart rate helps to increase oxygen delivery to working muscles and aids in removing of waste products
Increased stroke volume
Amount of blood ejected from the left ventricle with each beat. Stroke volume increases during exercise and plateauing between 40-60% of maximum heart rate
Increased cardiac volume
During exercise, cardiac volume increases as a result of increases in both heart rate and stroke volume. Designed to bring about an increase in oxygen delivery.
= Stroke volume x Heart rate
Increased systolic blood pressure
Systolic blood pressure is the pressure created with each contraction and systole of the heart. The harder the heart pumps, the higher the systolic blood pressure
Redistribution of blood flow
The redirection of blood flow to working muscles during exercise is caused by a mechanism called the vascular shunt mechanism
Increased venous return
Because a closed circuit exists, the more blood will be pumped of the heart, the more blood will return to the heart. This is assisted by muscle pumping action and one way valves in veins
Increased AVO2 difference
The difference in oxygen concentration between the atrioles and the venules. An indirect measure of how much oxygen muscles are using. Caused by a decrease in plasma volume due to sweating. It depends on intensity, duration and environmental factors
Acute respiratory responses to exercise
Increased respiratory rate, Increased ventilation, Increased tidal volume and Increased pulmonary diffusion
Increased respiratory rate
Number of breaths taken per minute. Breathing rate rises sharply and can increase to as high as 30-50 breaths per minute. This helps deliver oxygen to working muscles
Increased ventilation
Amount of air inspired or expired per minute by the lungs. The more air, the more oxygen delivered to working muscles
= Respiratory rate x Tidal volume
Increased tidal volume
Amount of air inspired or expired per breath. The depth of breathing (tidal volume) increases from 0.5L at rest to as high as 3.5L at maximal efforts
Increased pulmonary diffusion
The movement of oxygen and carbon dioxide from areas of high concentration to low concentration between the alvioli and the surrounding capillaries
Acute muscular responses to exercise
Increased motor unit recruitment, Increased muscle temperature, Decreased energy substrate scores, Increased AVO2 difference, Increased enzyme activity, Accumulation of lactic acid, Transport of oxygen by myoglobin and Production of ATP in the mitochondria
Increased motor unit recruitment
When an individual engages in physical activity, there is a need for muscular contractions to take place. The greater the force or effort required, the greater the number of motor units recruited
Increased muscle temperature
Increased blood flow to the muscles, coupled with the heat generated as a by product of the increased production of ATP during exercise results in an increase in muscle temperature
Decreased energy substrate scores
Muscular stores of ATP, Creatine Phosphate, Glycogen and Triglycerides begin to deplete during exercise as they are sources of fuel for production of ATP. The depletion of these energy stores particularly Creatine Phosphate and Glycogen contribute to fatigue experienced during exercise and physical activity
Increased AVO2 difference
During exercise, working muscles extract much more of the available oxygen from the blood. As much as 75% of the available oxygen is extracted and as a result there is an increase in AVO2 difference
Increased enzyme activity
Enzyme activity increases during exercise to produce the increased amount of ATP required by the muscles. This is because enzymes assist in the chemical reactions that resynthesises ATP
Increased transport of oxygen by myoglobin
Myoglobin carries oxygen within the muscle. During exercise, there is an increase in oxygen being carried by myoglobin
Increased production of ATP in the mitochondria
The mitochondria are the site of an aerobic metabolism within the muscle. During exercise, there is an increase in ATP resynthesis within the mitochondria
