Chapter Seven : Acute Responses to Exercise Flashcards
Acute responses definition
An immediate change in the respiratory, cardiovascular and/or muscular system in response to exercise
Respiratory acute responses
Respiratory rate
Tidal volume
Ventilation
Diffusion
Cardiovascular acute responses
O2 consumption a-VO2 difference Cardiac output Venous return Blood pressure Redistribution of blood flow
Muscular acute responses
Temperature
Motor unit recruitment
Energy substrates
Lactate
Ventilation definition
How much air is breathed in or out in one minute (L/min)
Ventilation during exercise
Increases during exercise as tidal volume and respiratory rate increase
At submax intensity, ventilation will increase linearly
At max intensity, ventilation will increase until the exercise is stopped
Ventilation equation
Tidal volume (L/breath) X Respiratory Rate (brreaths/min)
Tidal volume definition
How much air is inspired or expired in one breath
Respiratory rate definition
The number of breaths taken in one minute
Ventilatory threshold
The point where ventilation is no longer increasingly linearly with the exercise intensity. Occurs at 65-75 % of max O2 consumption
Diffusion in at the alveoli
O2 concentration in the lungs is high so it diffuses into the bloodstream
CO2 concentration in the bloodstream is high so it diffuses into the alveoli
Diffusion at the muscle
O2 concentration is high in the blood stream so it diffuses into the muscle
CO2 concentration is high in the muscle so it diffuses into the blood
Diffusion during exercise
The surface area of the alveoli and the muscle increase so more O2 and CO2 can be exchanged increasing rate of diffusion
Cardiac Output definition
The amount of blood pumped out of the heart in one minute (L/min)
Cardiac output equation
Cardiac output (Q) = Heart Rate X Stroke volume
Heart rate definiton
The number of times the heart beats in one minute (bpm)
Stroke volume definition
The amount of blood ejected from the left ventricle per beat (L/beat)
Cardiac output during exercise
Increases as exercise intensity increases
Stroke volume increases as there are stronger contractions of the heart, reaches a maximum
Heart rate increases until the max is reached which is 220-age
A trained athlete has a larger SV than an untrained athlete
VO2 definition
Is the volume of oxygen that can be taken up and used by the body
VO2 during exercise
As exercise intensity increases so does O2 consumption
a-VO2 difference
The difference in O2 concentration in the arterioles compared to the venules; a measure of how much O2 the muscles are extracting from the blood
a-VO2 difference during exercise
As exercise intensity increases the working muscles extract greater amounts of O2 from the blood, increasing the a-VO2 difference. It can reach 100%
Venous return definition
The flow of blood back to the heart
Venous return during exercise
The heart can only eject how much blood it had in its ventricles so venous return increases to return more blood to the heart
During exercise the venous return is increased via the muscle pump, respiratory pump and venoconstriction, and one-way valves
Venous return muscle pump
When the muscles contract they squash the veins pushing the blood back up to the heart, the blood catches in the valves
Venous return respiratory pump
During expiration the veins filled with blood to be pushed up, respiratory rate increases making the pump more effective
Venous return venoconstriction
When the veins constrict pushing the blood towards the heart, reflex action
Blood volume during exercise
During aerobic exercise, blood volumes decrease depending on intensity, environmental factors (temp) and level of hydration
Due to the fluid loss from sweat, decreases blood plasma
Redistribution of blood flow during exercise
At rest 80% of blood is directed to the brain and internal organs
At submaximal intensity 50-60% is directed to the working muscles
During max intensity 80% is directed to the working muscles
Arteries vasoconstrict to the areas not needing blood
Arteries vasodilate to the areas needing blood
Redistribution of blood flow
Provides O2 and fuels needed for energy production and to remove waste products from working muscles
Blood pressure during exercise
Increase in cardiac output increases blood pressure
Both the systolic and diastolic blood pressure can increase, systolic increases more in exercise
Aerobic exercise causes a rise, however higher intensity increases it more
Systolic blood pressure definition
Pressure in the arteries following contraction of ventricles as blood is pumped out of the heart
Diastolic blood pressure definition
The pressure in the arteries when the heart relaxes and ventricles fill with blood
Diastole definition
The relaxation phase of the heartbeat
Systole definition
The contraction phase of the heartbeat
Increased blood flow during exercise (muscular responses)
The skeletal capillaries open up to allow increase in total muscle blood flow, deliver large blood volume with min increase in blood flow velocity and increase surface area to increase diffusion rates
Recruitment and activation of muscle fibres during exercise
During exercise the brain signals to increase the amount of motor units used
Smaller, slower twitch fibres that are slower to contract are recruited first then the largest fast twitch fibres are recruited
Motor unit principle
When a motor unit is activated it will contract maximally or not at all
Motor unit definition
A motor neuron and the muscle fibres it stimulates
Energy substrates during exercise
ATP is used up really quickly
Glycogen is then used
All fuel substrates decrease within the muscles as they are used up
Lactate during exercise
Lactate remains stable being removed through oxidation until the lactate inflection point is reached and then the lactate increases quickly, unable to be removed and causing fatigue
Body temp during exercise
Heat is a by-product of converting chemical to electrical energy
Sweat glands activate and the blood flow increases to the skin allowing heat to be released through the skin
