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