Hapter 4 Flashcards
Acute response
Something that happens in the body straight away
3 types of Acute Responses to exercise
Cardiovascular
Respiratory
Muscular
What is the response dependent on?
Intensity and length of exercise
Aim of response
1- Get more O2 in (respiratory)
2- Deliver it quicker (cardiovascular)
3- Use it more effectively (muscular)
Acute respiratory responses to exercise
Ventilation
Tidal Volume
Respiration Rate
Ventilation
(how much air is breathed in or out in one minute)
V (litres per minute) = TV (litres) × RR (breaths per minute)
- Increases during exercise as Tidal Volumne and Respiratory Rate both Increase
- Plateus after 4 or 5 minutes during submaximal exercise
- During maximal intensity, ventiliation continues to increase unitll the exercise is stopped.
tidal volume (TV)
(how much air is inspired or expired in one breath
- Exercise will increase depth of breathing thus more air per breath
- Will plateau/ or slightly down at max effort
respiratory rate (RR)
(the number of breaths taken in one minute)
- Increases during exercise to get more air into the lungs
Diffusion
Exchange of gas between the alveoli(airsacs in the lungs) to capillaries (blood vessels) in the lungs
Diffusion - gas moves from high to low concentration
In Alveoli - O2 High, Co2 is low
In Capillaries - O2 low, CO2 is high
- Diffusion allows O2 to move from lungs to blood and CO2 from blood to lungs
Cardiovascular responses to exercise
cardiac output (Q) stroke volume (SV) heart rate (HR)
Heart Rate
(Amount of beat p/m)
- Increases linearly as exercise intensity increases
- WIll increase until oxygen demands have been met, then level off, as the body has reached steady state. With increasing workloads, heart rate will increase linearly until max HR is met.
Stroke Volume
(Amount of blood ejected by heart per beat)
- Increases as exercise intensity increases but reaches peak before maximal intensity
Cardiac Output
(Amount of Blood ejected by heart per beat)
- HR x SV = CQ
- Increase during exercise as both HR and Stroke Volume increase
- As exercise reaches maximum HR will be close to its maximum although Stroke Volume will decrease
Blood Volume
(Consists of RBCs, WBCs, Plasma and Platelets)
- Decreases during exercise due to loss of plasma via sweat
- Amount determined by intensity and environment
Blood pressure
(Pressure in arteries when heart beats or relaxes)
systolic blood pressure - pressure in arteries as heart beats
Diastolic Blood Pressure - pressure in arteries as heart relaxes
Increased Cardiac Output = Increased Blood Pressure
Venous Return
When muscles contract, veins are constricted forcing blood back to the heart
- During exercise venous return increases due to greater muscle contraction
Redistribution of Blood Flow
Blood vessels open up (vasodialation) to allow blood to flow through muscles
- Blood vessels can also close up (vasoconstriction) to restrict blood flow to other areas where it is not needed
AVO2 Difference
Difference in oxygen concentration in the arterioles compared with the venuoles
- During exercise, the muscles uses up more o2 so less O2 will be in the veins
- Exercise requires more O2 to be used by the muscle, so the diff is greater
Acute Muscular Responses to exercise
Increased blood flow Motor unit recruitment Energy substrates Lactate Body temperature
Increased blood flow
During exercise, blood is directed away from non-essential organs to the working muscles.
-During exercise, skeletal capillaries open up and serve three main purposes. These are to:
• allow for increases in total muscle blood fl ow
• deliver large blood volume with minimal increase in blood fl ow velocity
• increase the surface area to increase diffusion rates.
-This results in an increase in blood flow to the working muscles, allowing for greater delivery of oxygen to meet the metabolic demands of the exercise.
Motor unit recruitment
motor unit - a motor neuron and the muscle fi bres it stimulates
During exercise, the brain can increase the number of motor units recruited, or it can increase the frequency of messages sent to activate the motor unit.
Depending on the required strength and speed of the contraction, the number of motor units recruited, and the rate at which they are recruited, can be adjusted.
-A motor unit will contract maximally or not at all, depending on the strength of the stimulus
Energy substrates
When exercise begins, muscular contractions can be fuelled initially by the ATP stored in the muscles. However, this ATP is in relatively short supply and when it is used up, the muscles must then rely on energy substrates to fuel metabolism. Glycogen is used in both anaerobic and aerobic respiration to produce ATP. During exercise, phosphocreatine (PC) donates a phosphate to adenosine diphosphate (ADP) to resynthesise ATP.
Intramuscular substrate levels decrease: ATP, CP (greater decrease at maximal intensity) Glycogen, triglycerides (greater decrease at submaximal intensity)
Lactate
As exercise starts, large amounts of lactate are released from the muscle due to anaerobic production of ATP.
This means that in submaximal exercise, there is a sharp increase in lactate – until oxygen consumption can increase to meet the energy demands of the muscle, and the lactate can be delivered to sites for removal
Body temperature
An increase in the rate of reactions is accompanied by an increase in heat production, which causes body temperature to increase also.
However, at high intensities, blood vessels vasoconstrict (rather than dilate, as they do in submaximal exercise) which hinders heat transfer to the skin and increases the risk of heat-related injuries during exercise.
During submaximal exercise, there is an increase in the amount of oxygen delivered to the working muscles. Which mechanisms are responsible for this increase, and what effect does this have on energy production
Ventiliation, Diffusion, HR, SV, CQ, Venous Return, Redistribution of Blood Flow
WHen there is sufficient oxygen available in the muscle, aerobic respiration can occur in the mitochondria. This allows muscular contractions to continue to occur once the immediate energy fuels have been depleted, and exercise can continue. It also allows for the efficient breakdown and removal on by-products
WHat is the relationship between Oxygen consumption, Cardiac Output, and AVO2 Diff
VO2 = CQ x AVO2 diff. (also needs a written explanation)
How is the response of the respiratory system to submaximal exercise different to its response to maximal exercise?
During submaximal exercise, the respiratory system will increase ventilation by increasing both TV and RR linearly, with respect to oxygen consumption, until a steady state is reached. At this point there will be no further increase in ventilation. During maximal exercise, ventilation will continue to increase until exercise ceases. The increase in ventilation is a result of increases in RR only. The rate of increase is linear up to the ventilator threshold, at which point ventilation increases faster than oxygen consumption.
Why does blood pressure increase more dramatically with resistance exercise compared with continuous exercise
Resistance exercises cause compression of the blood vessels by the muscles causing an increase in blood pressure. Blood pressure can also increase due to the Valsalva response elicited in heavy resistance training, where air is forcefully expired against a closed airway. 3
What major blood flow changes occur during submaximal exercise? How does this relate to the AVO2 DIff
During exercise blood is redirected to the working muscles. This means more blood is delivered to the muscles and the muscles can extract greater amounts of oxygen to be used for energy production, causing an increase in a-vO2 differenc
Explain how the mechanisms responsible for increasing the oxygen delivered to the working muscles are interrelated
Each of the mechanisms has an impact on the others. Increases in ventilation and diffusion mean that more oxygen is available in the blood. Increases in cardiac output mean more blood is pumped out with each beat and delivered to the working muscles. The increase in venous return means that more blood is available to be ejected with each beat. Increases in cardiac output and a-vO2 difference lead to an increase in oxygen consumption (the amount of oxygen that can be taken up and used by the body).
If motor units always contract maximally, explain how the body controls movements that require more or less force
Fewer motor units are recruited for activities that require less force; more motor units are recruited for activities that require more force.
WHy does lactate only lactate only accumulate at high intensity exercise?
At rest and during submaximal exercise intensities, lactate is produced, but sufficient oxygen is available for it to be broken down and removed by the body. At high intensities, lactate is being produced at higher rates than the body can clear it so it accumulates.
Explain the relationship between body temperature and redistribution of blood flow in the body as a result of continuous exercise
At submaximal exercise intensities blood flow is directed to the working muscles and to the skin to aid in temperature control. At maximal exercise intensities the increased demand for oxygen means that more blood is directed to the muscles and less to the skin (2 per cent) which means that temperature increases and the risk of heat related injuries increases.
why does the body need to make physiological changes when begininning exercise
TO accommodate the energy requirement of the exercise
Ventilatory Threshold
Point where ventilation increases at a non-linear rate,
WHat indicates an efficient circulatory system
A lower heart rate, together with an increased stroke volume. For a given cardiac output, the heart does does not have to beat as often to eject the same amount of blood.
WHen does stroke volume reach a maximum?
It reaches a maximum during submaximal workloads, any further increase in cardiac output is a result of an increase in heart rate
Vasoconstriction
A decrease in the diameter of a blood vessel, resulting in a decrease in blood flow to the area supplied by the blood vessl
Vasodialation
An increase in the diameter of the blood vessl resulting in an increase in blood flow to the area supplied by the blood vessel
How does blood flow to the skin assist body temperature regulation?
Through heat exchange witht he environment. As exercise increases, blood flow to the skin also increase, but as exercise approaches a maximum, blood flow to the skin decrease
How does blood supply to the hreart increase during exercise
Vasodialation of the coronary arteries assists in directing blood through these vessels to supply the heart muscle with the extra oxygen it needs
WHat happens after 30 minutes of exercise in terms of HR and SV
Heart Rate will increase but stroke volume will decrease. These changes are equal in size so Cardiac Output remains the same
Systolic Blood Pressure
Pressure in the arteries flowing contraction of ventricles as blood is pumped out of the heart
Diastolic Blood Pressure
Pressure in the arteries when the heart relaxes and ventricles fill with blood
Compare and Contrast the energy substrate levels of a 100m Sprinter and a marathon runner at the end of their events
100-metre sprinter: decreases ATP and CP stores; marathon runner: decreased glycogen and intramuscular fat stores
oxygen defi cit
temporary shortage of oxygen in cells, typically at the start of exercise where oxygen demands are greater than the body’s ability to supply the necessary level
- While oxygen deficit continues, the body must obtain ATP from its anaerobic energy systems, which don’t rely on oxygen
steady state
when the body is able to supply suffi cient oxygen to meet the oxygen demands
oxygen debt
a deficit of oxygen resulting from INTENSE exercise
- At the completion of exercise, the demand for ATP decreases dramatically. However, the amount of oxygen consumed still remains above the amount required at resting levels. This is known as an oxygen debt, and typically occurs once exercise has fi nished and oxygen consumption stays above resting levels during the warm-down.
- An oxygen debt can occur only after the body has undertaken anaerobic exercise. Exhausting, high-intensity, anaerobic exercise results in a larger oxygen debt than exercise at lower workloads or intensities
excess post-exercise oxygen (EPOC)
excess post-exercise oxygen consumption; another term for oxygen debt
The two parts of oxygen debt
The oxygen debt can be further divided into two ‘parts’. The fi rst (or fast) replenishment part is primarily involved in restoring phosphocreatine (PC). This takes approximately 2 to 3 minutes, in which time 2 to 3 litres of oxygen can be consumed to provide energy for this resynthesis. The second (or slow) replenishment part is primarily concerned with removal of lactic acid through buffering.
buffering
absorption of H+ ions in the presence of hydrogen carbonate produced by the kidneys
relationship between exercise intensity and the related factors of oxygen defi cit, steady state and oxygen debt
An activity that calls upon the anaerobic energy systems rapidly will have a large oxygen defi cit, possibly a small (or no) steady state and a large oxygen debt or EPOC. An activity performed at a lower intensity will have a smaller oxygen defi cit, a longer steady state and a smaller oxygen debt. During activities where steady state has been established and the LA system is called upon increasingly to supply ATP (such as surges or short sprints), these contribute to oxygen defi cit and hence ‘add’ to the oxygen debt during recovery – essentially extending the slow-replenishment part. A person who has undertaken aerobic training will be able to consume a greater amount of oxygen during steady state, and thus the anaerobic energy system contribution becomes proportionately smaller at an earlier stage of the activity or performance.
