Exercise physiology report notes Flashcards
First 3 weeks are linked to lab report the rest are linked to the exam as well as seminars and labs
.
What does a heavy warmup do to aid race performance?
Blood flow to the muscle increased via increased cardiac output and vasodilation
Rate limiting enzymes in the respiratory chain primed, increasing muscle O2 extraction
Altered neuromuscular activity - more motor units recruited at exercise onset
What is anaerobic energy?
Generate energy rapidly without oxygen
Essential for high intensity sports performance
Involves the breakdown of PCr and glucose/glycogen
Per and Glycogen get broken down in the cell
ATP-PCr reaction?
ATP = (Via ATPase) ADP +Pi + energy
Energy used for mechanical chemical and transport biological work
ADP then reacts with PCr via the enzyme creatine Kinase to regenerate ATP and produce Cr
Find Graphs for PCr during exercise and recovery?
How low does PCr fall?
Do low levels lead to exercise cessation?
ok
Find graph for PCr and VO2 responses in recovery from exercise
ok
Overview of glycolysis?
Job is to phosphorylate ADP
Initially glucose is provided through breakdown of muscle glycogen (glycogenolysis)
Longer durations result in greater rates of glycolysis to assist glycogenolysis
Glucose enters cycle and is phosphorylated, occurs again at step 3,
Net gain of 2 ATP (3 if substrate is glycogen)
Main enzyme hexokinase is inhibited by G6-P
Another main enzyme PFK is inhibited by ATP and citrate, but activated by F6-P, ADP and Pi
Features of anaerobic glycolysis?
Key steps are 7 and 10
Step 6 crucial aspect is availability of NAD+
What determines which energy system is utilised?
Exercise intensity and exercise duration
What’s the crossover concept?
There’s a crossover
Energy system interaction rules?
PCr breakdown is always the most rapid system to respond following a change in intensity
PCr will be resynthesises only when exercise intensity is reduced (this is done aerobically, thus VO2 will remain elevated)
During low intensity exercise it is unlikely that PCr will deplete to less than 80% of the resting value (only 20% used)
VO2 will be operating at the desired level within most individuals
During intermittent type exercise this is more tricky and depends on passages of play, it is likely that VO2 will remain elevated , with periods of peaks, and slowly return back to the elevated baseline
Glycolysis can be considered to simply fluctuate directly with exercise intensity
Describe fatigue during high intensity exercise?
50-100 fold increase in energy consumption
Exceeds aerobic capabilities of the cell
Large fraction of ATP must come from anaerobic metabolism
High intensity causes a rapid decline in contractile function
Describe metabolite accumulation during high intensity exercise?
High rates of glycolysis and ATP hydrolysis causes a build up of the metabolites H+ and Pi
These have been proposed to reduce muscle force producing capabilities by interfering with key steps in the cross bridge cycle such as calcium sensitivity
Where in the cell does ATP-PCr reaction occur?
Cytosol
What is the role of NAD+ in anaerobic glycolysis?
To accept electrons allowing the continual breakdown of glucose
What happens when NADH and H(+) accumulate?
Lactate forms to free up NAD+
What’s aerobic metabolism?
refers to the ATP- generating reactions in which oxygen serves as the final electron acceptor in the ETC and combines with hydrogen to form water
Oxygen does not participate directly in ATP synthesis, but does determine the maximal rate that ATP can be produced aerobically
What does the abrupt increases in work rate allow the study of?
The amplitude
The rate
The profile
Important of VO2 response?
Faster VO2 kinetics results in less disruption to cellular homeostasis (PCr degradation, and metabolite accumulation)
Formula of O2 deficit?
= Change in VO2 x time constant
What is VO2 max?
Intergrated capacity of pulmonary, CV and muscle systems to uptake, transport and utilize oxygen
Or the maximum rate that ATP can be synthesised aerobically
The fick equation for VO2 max is?
= Q max x a-vo2 diff max
Q max = SV max x HR max
a-vO2 diff max = CaO2 - CvO2
What are the limitations of VO2 max?
Any step in the pathway of oxygen conductance from atmospheric air to the mitochondria could be a limiting step
Difference between central and peripheral?
Central = pulmonary diffusing capacity, maximum cardiac output, and oxygen carrying capacity of the blood (delivery)
Peripheral = includes extraction and utilisation of delivered O2 at the muscle (uptake/utilisation)
Central evidence?
General agreement that VO2 max for combined arm and leg work is the same
Arm work alone elicits 65-75% of ‘leg work’ VO2 max
Thus if limitation was peripheral, much higher
VO2 max values would be expected for combined exercise
That it does not is likely explained by limitations of central cardiovascular system
Peripheral evidence?
One legged training study VO2 increased in trained leg and not in the other due to mitochondrial volume and oxidative enzymes
Problem is doesn’t relate to the whole body
General consensus on VO2?
Tracks O2 availability but a greater effect is noted when delivery is reduced comported to when it is supplemented
When O2 delivery is enhanced, unless there is an increase in the aerobic capacity of the muscles, the magnitude of the expected gin in VO2 max is not realised
t is mainly the ability of the cardiorespiratory system to transport O2 to the muscles, not the ability of muscle mitochondria to consume O2, that limits VO2max .
What’s the steady state (CWR)?
The levelling off increasing VO2
What’s oxygen uptake slow component?
Second increase after levelling off of vo2, sometimes difficult to distinguish and blends into the first one
Key to the lab report:
Why normalise:
Understand the sub-maximal thresholds
Differing physiological responses
The exercise intensity domains:
Be able to explain demarcations (boundaries)
Be able to explain (and identify) the physiological responses
The oxygen uptake slow component
What does normalising mean?
Attempting to ensure that the overall physiological demand experienced by the subjects is the same
What is exercise intensity?
The individuals physiological response to the external work
When is it important to normalise intensity?
Studies designed to measure the physiological or perceptual impact of an intervention
When designing training programmes
Why account for exercise intensity?
Metabolic, gas exchange and perceptual responses vary greatly at different intensities
Intra and inter individual variability clouds real changes
What underpins the variance in response?
Submaximal thresholds:
Lactate or gas exchange threshold
Critical power/velocity
What’s lactate threshold
The highest oxygen consumption or work rate in which less than 1.0Mm increase in blood lactate concentration above resting levels
What’s the gas exchange threshold?
Excess H+ causes Bicarbonate buffering resulting in non metabolic Co2 and an increase in VCo2, when plotted against VO2 the break point indicates the occurrence of the lactate threshold
How to find critical power?
do 4 or 5 tests to exhaustion allows you to find asymptote at the bottom which is the critical power
Or you can do a 3 minute test and end power is the critical power
Why is vo2 max % not great to test with?
Doesn’t take the lactate threshold into account
What is the vo2 slow component associated with?
Elevated blood lactate, Per degradation, elevated body temperature, increased catecholamine circulation, increased ventilatory and CV work, and a greater recruitment of type 11 muscle
The 4 exercise intensity domains? (Only viable during constant work rate exercise, intermittent exercise involves dynamic transition between the domains)
Moderate: All work rates that are bellow the lactate threshold, so blood lactate is not elevated
VO2 increases at 10ml.min^-1.W^-1 (known as gain) So it’s change in Vo2 in change in Watts
Can continue for about 4 hours
Fatigue related to muscle glycogen depletion, muscle damage, increased core temperature
Heavy: Is above lactate threshold where a steady state of Vo2 will eventually be attained, upper boundary is critical power
After 2-3 minutes Vo2 continues to increase via the slow component (higher if closer to critical power)
Even if exercise is completed to exhaustion VO2 remains sub maximal
30-120 mins
Fatigue due to metabolite accumulation and substrate availability
Severe: Work rates above critical power where VO2 max is attained if exercise is continued to exhaustion
It’s the slow component that causes it to reach its max
A steady state will never be reached
It encompasses a wide range of Work rates for which VO2 max can be attained
The boundary above will be the work rate in which exhaustion is reached before Vo2 max is
2-30 minutes
Fatigue is related to PCr depletion and accumulation of fatiguing metabolites
Extreme:
Work rates so high that exhaustion ensues before VO2 max is attained
Time to exhaustion is around 90 seconds
Fatigue mechanisms same as extreme
how to calculate gain?
Increase in VO2 above baseline / Work load
Mechanisms underpinning the slow component or not?
Stabilisation of trunk muscles uses more oxygen as work rate increases, but treadmill work discounts this
Lactate can’t be it as McArdles syndrome patients who can’t produce lactate still show the slow component
Also infusing lactate into blood made no difference into the slow component
Cardiac/ventillatory work disproven by 91% of the slow component comes from the exercising musculature
Catechomalines disproven as injected adrenaline didn’t make a difference on slow component
Muscle temperature disproven as increasing temperature had no effect on the slow component
Additional motor unit recruitment:
Type 11 muscle is less economic than type 1
Original hypothesis was that additional type 11 fibres were recruited to replace fatiguing fibres
Proven correct
What’s the delta concept?
A method for defining exercise intensity which considers both the lactate threshold and the VO2 max
First an incremental VO2 max test is completed enabling determination of power at VO2 max and power at lactate threshold
(VO2 max power - Lactate threshold) x power desired% + power at lactate threshold
Doesn’t go into the lab report
What should the report be about?
Estimation of exercise intensity using oxygen uptake, heart rate and blood lactate data
From these data (alone in combination) can we estimate the intensity domain that a bout of CWR exercise was conducted in?
With no knowledge go boundaries (VO2 max, LT/GET, CP/MSS)
What did we do in the lab?
2 exercise intensities
Collection of gas exchange, HR, Blood lactate
2nd bout was 15 mins or to exhaustion
Instructions for data analysis on ELE
Ok
Do we have to analyse data for all bouts?
Yes
How do you name the files of data?
B1-B6
Gain formula?
(Average VO2 in last 30s in last 30s of exercise - Ave VO2 in last 30 secs of Baseline ) / (Workrate - 20W)
Units are mL.min^-1.W^-1
Tells us every watt of exercise done at this intensity they used a value in mL of oxygen per minute
A higher gain means individual is using more oxygen per unit change in workload -
Indication of VO2 slow component?
End exercise VO2 - VO2 at 3 minutes
Clarification of exercise intensity domains?
Moderate is bellow lactate threshold
Heavy is above lactate threshold, but below maximum steady state
Severe - above maximum steady state achieving VO2 Max
Extreme - Exhaustion before VO2 max
Rough guide for what domain gain represents?
Wilkerson et al 2004
Moderate = 8-11 mL.min^-1.W^-1 Heavy = 9-12 mL.min^-1.W^-1 Severe = 8-14 mL.min^-1.W^-1 Extreme = smaller than 8 mL.min^-1.W^-1
The overlap is due to the VO2 slow component and time to exhaustion
So should only be used in combination with other measurements
These values are broadly correct however significant inter-individual variation can occur in moderate and heavy values (ie. much higher values are seen in individuals with a greater % of type 2 muscle fibres
Gain is determined by how the primary Vo2 increase and slow component Vo2 respond to power output
Body tries to get a steady state using value of 10
Values are lower than 10 in moderate can be due to the person having very good exercise economy
If low values are seen in heavy person has very small slow component, exercise is just above lactate threshold
If low values seen in severe means subject has a high primary amplitude and low VO2 slow component truncated at VO2 Max, this coupled with the high power = low gain (very near the extreme domain)
If Extreme gain will be lower the further you get into it
Scenarios for higher than expected gain?
Moderate - individual has poor exercise economy
Heavy - subject has large slow component (near the severe boundary)
Severe - subject has a very large slow component that has resulted in the attainment of VO2 max (exercise near the heavy boundary)
Extreme - the closer to the severe boundary it is
What is EE-3 (can only be used if you have a minimum of 4 mins of loaded data)?
An estimate of the magnitude of the VO2 slow component
Is only evident above the lactate threshold
Magnitude of the slow component increases through the heavy domain
Large slow components are generally noted just into the sever domain - reach VO2 max the slowest
Magnitude of slow component is reduced at upper end of the severe domain because?
The response is dominated by the primary increase in VO2
The response has a ceiling of VO2 max
Exercise duration is short
Has to be built in
How to calculate EE-3?
(Ave Vo2 in last 30s of exercise - Ave VO2 from 170-190s) (think that is from baseline)
How do determine if a slow component is meaningful?
Calculate the EE-3 as a percentage increase in VO2
Increase in VO2 = Vo2 at end of exercise - baseline Vo2
(EE-3 / increase in VO2) x 100
Smaller than 5% is inconclusive
5-15% = heavy
0-30% = severe
Also look if it’s levelled off or has it levelled off
Presentation of data?
Present a clear table of key data
Good figures showing the VO2 responses, adding VO2 and HR data to the same figure is very effective on a different axis
Will have 6 figures for each data
Rest of data in a table
Rough guide for words?
Intro - 300-400
Methods - 300 words max, does not count to the word limit
Results/Discussion/Conculsion 600-700 words
So 1000 words max
Word count includes - all text, headings and subheadings, references within the text, Table and figure descriptions,
Not included - Methods, words in tables that contain data, words in figures (axes), reference section, Title and title page, equations
Structure?
Intro:
Why normalise (must detail when and why accounting for exercise intensity is important)
Description of the domains and the physiological responses in each of them
Define the lactate threshold and critical power
Define VO2 gain and slow component
Aim - is it possible to determine exercise intensity without VO2 max and sub-maximal thresholds
Methods:
Details of the timings and durations of the bouts
What measurement were taken and when
What equipment was used (including manufacturers info)
Equations correctly included
Subject info not required
No stats required
Results and discussion:
Combine these for this report
In the first few sentences have a short summary of main findings and link back to aim
Include figures and tables
Estimation of the domains of your chosen bouts with reasoning
Do this for B1-B6 each having their own figure
Make sure to go through each variable everytime
Concise conclusion - has to decisive
Formatting?
Size 12 font Arial
Double lined spaced throughout
Section headings
Harvard system for referencing
Getting started
Do all the background reading
Need to be able to describe the physiological responses in the different domains
Analyse the dat calculations and classify the bouts
Create figures and tables that display the data
What to look for?
Is a steady state reached
Is there a slow component
Blood lactate level
What is the value at the end of exercise
Heart rate:
Steady state reached
Does it increase after 3 mins
End exercise HR (calculate as a % of estimated max (220 minus age)
Time to exhaustion if under 15 minutes indicates that it must be above the critical power
Only need 4 or 5 references
ok
Picture taken of mark scheme
ok
