U3AoS2 - Oxygen Uptake and Acute Responses Flashcards
Oxygen uptake at rest
Minimal oxygen consumption as ATP demand is low.
Oxygen consumption at rest
0.3 L of oxygen per minute
What fuel substrates are used at rest?
Carbohydrates and Fats
The amount of oxygen entering the bloodstream is…
Proportional to the amount used by tissues for oxidative metabolism
What happens to oxygen consumption as intensity increases?
As intensity increases, consumption of oxygen increases for greater ATP resynthesis.
As the athlete moves from rest and into activity
O2 uptake increases as the body attempts to meet oxygen demand.
- Cardiovascular and respiratory systems increase O2 uptake and transport
Muscles
utilize and consume oxygen
Transition from rest to exercise
Shortfall between the amount of O2 required for exercise and amount supplied.
This is called oxygen deficit
Oxygen deficit
- Oxygen demand exceeds oxygen supply
- Anaerobic systems will be dominant
- Once oxygen becomes available to meet demand, steady state is reached.
Why does oxygen deficit occur?
Respiratory and Cardiovascular system take time to adjust to the new oxygen demand.
- Amount supplied lags behind amount needed
Steady state can only be reached when
Necessary adjustments are made to increase oxygen supply
Increased:
- respiratory frequency
- tidal volume
- heart rate
- stroke volume
Steady State
Oxygen supply meets oxygen demand
- aerobic steady state
- ATP supplied aerobically
- Heart rate and oxygen consumption remain constant
- No need for further increase oxygen uptake and little reliance on anaerobic pathways
How long does it take for steady state to be reached?
One minute or more depending on intensity for oxygen supply to increase sufficiently to meet oxygen demands.
Physiological response during Steady State
- coincides with a plateau in heart rate and ventilation as enough oxygen is reaching the working muscles
If intensity increases again
- demand for ATP and oxygen uptake increases
- short delay before O2 uptake increases sufficiently
- anaerobic systems briefly increase contribution until another steady state reached.
A steady state can only be reached when
Lactate production is less than lactate removal.
- Steady states can only be help up to and including Lactate Inflection Point
Oxygen deficit in trained athletes
Oxygen deficit is reduced due to athletes attaining steady state sooner.
EPOC stands for
Excess post-exercise oxygen consumption
EPOC
Body is taking up, transporting and consuming more O2 than is required at low intensities
Consuming more O2 as it is trying to return the body to pre-exercise state
Fast Part
First 3 minutes
- Resynthesize PC and ATP
- Restore O2 to the myoglobin
Slow Part
Following 3 minutes
- oxidation of hydrogen ions
- convert lactic acid to CO2 and H2O
- return core temperature, HR and V to pre-exercise levels
- Convert lactic acid to glycogen
Factors affecting duration of EPOC
- duration
- intensity
- fitness levels
The greater the intensity the greater the EPOC
Impact of training on O2 deficit, steady state and EPOC
- lower HR
- faster recovery
- improved ability to transport O2
- reach steady state faster
Anaerobic activities
- increased oxygen deficit and EPOC
Acute Responses
- Body responds physiologically to meet increased energy demand
- Immediate short-term responses that last only the duration of activity and recovery
- Dependent on duration, intensity and type of activity
Acute responses can be observed in
Respiratory, cardiovascular and muscular systems
- coordinated response to meet increased energy demand
The 3 systems work together to
- supply more energy, ATP and oxygen
- Remove any waste products (CO2 and metabolites)
Respiratory system
Designed to facilitate an increase in availability of oxygen and removal of CO2.
Respiratory Acute Response
Increased
- Respiratory rate
- Tidal volume
- Ventilation
- Pulmonary diffusion
- Oxygen uptake
Ventilation
How much air we breathe in and out per minute
Tidal volume x Respiratory rate
Respiratory rate
Number of breaths per minute
Tidal volume
How much air is inspired and expired in one breath
L/breath
Increased ventilation mechanism
- Beginning exercise causes receptors in the muscles stimulate an increase in ventilation
- Triggered by an increase in CO2 and Heat in the blood
- Process controlled by respiratory control system in the brain
Ventilation during submaximal activity
RR, TV and V all increase quickly then plateau
- Relationship between VO2, and intensity is linear
- Air is able to enter the lungs, diffused and transported.
Ventilation at Maximal intensities
- Tidal Volume Plateaus
- Any further increase in ventilation is due to an increase in Respiratory rate
- At progressive higher intensities, ventilation increase is not in proportion to VO2 or intensity
Why is it important to increase oxygen uptake?
Increasing oxygen means more ATP can be resynthesised aerobically
- Produces a greater amount of ATP
- Less fatigue
Increasing respiratory rate
More air entering the lungs, more oxygen
Increased Tidal Volume
More oxygen into the lungs
- greater opportunity for O2 to be diffused into capillaries
Anticipatory response to exercise
Heart rate rises above resting levels just before exercise
Due to the release of epinephrine
Benefit of the anticipatory response
Smaller oxygen deficit period, reach a steady state faster
Increased pulmonary diffusion occurs as
the surface area of the alveoli increases during exercise as a result of increased tidal volume.
Diffusion
Gases move from high concentration to low concentration
Pulmonary diffusion
- Exercise increases the rate of gas exchange allowing more oxygen into the bloodstream
Inspiration
Oxygen moves from high concentration in the alveoli to low concentration in the blood.
Expiration
Carbon dioxide moves from high concentration in the venous blood to low concentrations in the alveoli
Benefit of increasing pulmonary diffusion
- Increased delivery of oxygen and removal carbon dioxide and metabolites at higher intensities.
- enables higher aerobic intensities
Cardiovascular system
Heart, blood and blood vessels (arterioles, veins and capillaries)
Role of the cardiovascular system
Delivers blood carrying oxygen to the muscle and assists in removal of carbon dioxide.
Cardiovascular system acute responses
Increased
- heart rate
- stroke volume
- cardiac output
- blood pressure (no performance benefit0
- avo2 difference
redistribution of blood flow.
Stroke volume measurement
mL/beat
Heart rate measurement
beats per minute
Cardiac output
L/min