# App Phys week 3

version from 2017-01-26 19:36

## Section 1

Whats important about efficiency and economy?its a multiplier so small increases/decreases have big impact
What is the model for efficiency effects?(performance VO2 aerobic + performance O2 deficit anaerobic) x gross mechanical efficiency = performance velocity or power
What morphological components can affect performance VO2?muscle capillary density, stroke volume, max heart rate, haemoglobin concentration, aerobic enzyme activity etc
What can affect performance O2 deficit (anaerobic)?total buffering capacity
What are the VO2 max values for different fitness levels according to Rowell (1993)?sedentary = 30. normally active = 45. conditioned = 53. endurance athletes = 85
What is oxygen deficit?at the start of exercise, VO2 increases but demand outweighs supply, so for the first 2-3 minutes, anaerobic biproducts supply energy - anything above the VO2 curve before this time is O2 deficit
What %VO2 max do endurance athletes compete at?75-80%

## Section 2

What factors limit VO2 max?respiratory components, central components (cardiac output) and peripheral/metabolic components (capillary density)
When do respiratory limitations affect VO2 max?during high intensity exercise, not low intensity (submaximal exercise). not significant in subjects with normal pulmonary function
What can happen to marathon runners in some circumstances?can undergo arterial desaturation - cardiac output is high so transit time of blood can be too quick for oxygen absorption - respiratory limitation
How can you work out VO2 max using CO and AVO2 difference?CO x AVO2 difference = VO2 max (AVO2 = difference between o2 saturation in arterial and venous blood, measure of how quickly O2 is removed in capillaries) (CO also known as Q value)
In single knee extension, what can the maximal blood flow be to the quadriceps?6-7L/min - 3kg of muscle, isolated activity, = 200ml/100g of muscle
During whole body exercise for someone with 30kg of muscle, to supply 6L/min blood, what does CO need to be?60L/min
What is the equation for CO?CO= SV x HR
Metabolic limitations?At VO2 max work rates, the flux through Pyruvate Dehydrogenase is adequate, glycolysis is adequate. no metabolic limiting factors of VO2 max
What does physical training improve with regard to VO2 max and the cardiovascular system?increases max CO, increases oxygen extraction from the blood.
In summary, what does training aid for VO2 max?decrease in HR, increase in SV, increased maximal intensity CO, increased blood volume and flow. oxygen extraction increases (greater capillarity, more mitochondria)

## Section 3

who might VO2 improvement training be more important to?middle distance runners
How much can VO2 be improved by?10-15%
what threshold should you exercise at to avoid fatigue?LT
What is efficiency/economy with regards to VO2?how much speed/power can be generated for VO2 level
why is a more efficient/economical athlete at an advantage?perform more work (more power/faster speed) for a given amount of energy. use less energy for a given amount of work
What can differ even if VO2 max and LT are the same in two different athletes?more power for same energy expenditure - if more energy is used, higher depletion of glycogen >>> fatigue quicker
What units is economy measured in?VO2/km/h - mostly relevant to running
How can efficiency be determined?thermodynamic efficiency - proportion og the free energy from ATP splitting that appears as mechanical work (v difficult to measure)
How can you determine mechanical efficiency?enthalpy = heat + work. efficiency = work/(heat + work) <<< v difficult to measure
Can you measure work rate in running?no
What is net energy?subtraction of energy expenditure at rest from gross energy
What is gross energy?all energy measured
What is work?accounts for the energy to move legs to pedal
What is delta energy?measurement between change in work rate (watts) and change in energy (kcal/min) (triangle on graph) >>> measurement of efficiency
What can affect efficiency?muscle fibre composition
What relationship exists between type I muscle fibre% and efficiency?positive correlation
What was found when high T1MF vs normal T1MF work at a set VO2 intensity? (horowitz et al 1994)high T1MF delivered more power than normal T1MF, higher type I muscle fibres = more efficient and better performance
How long does it take to improve efficiency?years and years
Paula Radcliffe - performance over yearsefficiency improved even though VO2 max declined, so she actually performed better

## Section 4

What showed that VO2 max may not be important when eritreans and spaniards were compared in marathon running?eritreans had VO2 max of 74ml/min/kg, spaniards had VO2 max of 78ml/min/kg but eritreans were faster in marathons
What showed that economy may not be as important as initially thought when eritreans and spaniards were compared?eritreans = 66 ml/min/kg, spaniards = 75ml/min/kg.
Why were eritreans thought to do better in marathons than spaniards?delayed glycogen depletion, reduced thermal stress through lower metabolic heat production. eritreans were small and around 56kg so were able to disipate heat better due to improved thermoregulatory systems