Sports Performance & Nutrition Flashcards
1
Q
What physiological variables are related to athletic performance?
A
- VO2 max
- Economy
- % VO2 max
- Lactate kinetics
- Muscle Fiber type
- Genetics
2
Q
What is VO2 max?
A
- The maximal amount of O2 used during prolonged high intensity exercise
- Important because: good indicator of current endurance fitness in a broad spectrum of people
o However, not in a group who all have high VO2 Max values
3
Q
What influences VO2 max?
A
- Influenced to some extent by sex, body size and age
o Males tend to have higher VO2 max than females, usually because of higher muscle mass
o Larger people have higher VO2 max values than smaller people
4
Q
What is VO2 and how is it calculated?
A
- VO2 = V of O2 consumed per minute (L/min)
o = (Vi x FiO2) – (VE x FEO2)
5
Q
What is VCO2 and how is it calculated?
A
- VCO2= V of CO2 produced per minute (L/min)
o = (VE x FECO2) – (VI x FiCO2)
o Can usually ignore inspired CO2 because fraction is so small
6
Q
How is O2 uptake related to power output?
A
- Steady linear increase in O2 uptake with increased work/power
- Usually reaches a max O2 uptake and plateaus, but not always
7
Q
What is economy?
A
- The amount of oxygen needed at a running speed that isn’t maximal.
- Improved economy means that VO2 at a relative speed is lower
- Training results in improved economy – i.e. at the same speed less O2 is needed
- Runner with better economy and the same VO2 max as another runner will reach that max VO2 at a greater speed.
8
Q
What is %VO2 Max?
A
- Incorporates both VO2 max and economy – more accurate determinant of performance
- Take VO2 at relevant speed and divide by VO2 max
- 85% VO2 max = the percentage that most well trained persons can exercise at for a prolonged period of time
- The most successful athletes can maintain a high %VO2 max during racing at any distance
9
Q
What is the Respiratory Exchange Ratio?
A
- RER = VCO2/VO2
- Indicates what sort of fuel substrate is being used to power a particular energy output.
- RER of 1 = 100% Carb fuel source
- RER of 0.7 = 100% Fat fuel source
10
Q
What is the lactate threshold?
A
- The point at which blood lactate begins to increase exponentially during exercise of increasing intensity
o Where lactate production exceeds lactate clearance. - Increase in lactate concentration is gradual at the beginning of exercise because clearance almost matches production
- As exercise intensity increases, L production increases.
- As production increases so does L clearance, although it doesn’t quite match clearance.
- When clearance can’t keep up with production (it plateaus) then lactate threshold is formed.
11
Q
What is the effect of training on the Lactate Threshold?
A
- Training shifts LT inflection point to the right (LT forms at higher speed/intensity)
- Clearance plateaus at an earlier intensity in untrained/less trained states.
- Training results in increased/improved lactate clearance
- Sometimes there is no clear inflection point – in that case draw random line across at 4mmol/L blood lactate and drop perpendicular at point where it crosses the lactate curve.
o This means you can still measure the right shift with training
12
Q
Is the lactate pathway a destructive pathway?
A
NO
- Common misconception is that lactic acid causes fatigue and muscle soreness
- Glucose/glycogen undergoes glycolysis to form pyruvate, releasing 2 H+ ions (making cellular environment acidic)
- Pyruvate can then be converted to lactate, consuming to H+ ions, and restoring the cellular environment.
- Pyruvate to lactate regenerates NAD which is needed in glycolytic pathway and consumes problematic H+ ions produced during glycolysis.
- THEREFORE: Good pathway, not destructive
13
Q
What type of muscle fibre do endurance athletes have?
A
High % Type 1 fibres
14
Q
What type of muscle fibre do Power athletes have? (Sprinters, powerlifters etc.)
A
High & Type 2 fibres
15
Q
What are the properties of Slow Twitch Oxidative Fibres?
A
Type I: o High Blood Supply o High Mitochondrial Density o High Triglyceride store o High Oxidative capacity o Low Glycolytic capacity o Moderate Creatine Kinase activity
