S1 Lecture 4 Flashcards
(16 cards)
What does VO2max measure?
Overall concept of aerobic capacity
VO2max represents the maximum rate of oxygen consumption during intense exercise.
What is the Fick equation for oxygen uptake (VO2)?
VO2 = HR x SV x (a-v)O2 difference
HR: heart rate, SV: stroke volume, a-v: arterio-mixed venous oxygen difference.
What are the primary factors that limit VO2max?
- Good cardiovascular health
- High cardiac output
- Well-developed oxidative capacity in skeletal muscle
Oxygen delivery is the primary limiting factor in healthy individuals.
What is the significance of acute exercise studies in understanding VO2max?
Isolated muscle can use more oxygen than the heart can deliver
Example: Maximum O2 extraction is 2-3 times higher in single legged exercises compared to double legged.
What is a ‘good’ absolute VO2max score?
2.5L/min
Absolute VO2max is the total volume of oxygen consumed per minute.
What is the difference between absolute and relative VO2max scores?
Absolute score is in L/min; relative score is in ml/kg/min
Relative VO2max accounts for body weight.
What is the protocol design to determine VO2max?
- Incremental exercise test to exhaustion
- Aim for 8-12 minutes for exhaustion
- Use large muscle groups
This stresses maximum cardiac output and avoids premature local muscle failure.
What are the primary criteria for determining VO2max?
- Plateau in VO2 despite load increase (less than 2ml/kg/min)
- Heart rate within 90% of age-predicted max
Secondary criteria include blood lactate concentration over 8 mmol/L, RER of 1.15 or above, and RPE > 18 on a 6-20 scale.
What is the relationship between VO2max and endurance performance?
Ability to use oxygen is the main physiological determinant of endurance performance
VO2max represents the maximal capacity but sustaining a high percentage of VO2max is also crucial.
What happens to VO2max after the age of 25?
Approximately 1% decrease per year
The decline may accelerate due to disease.
How does heredity affect VO2max?
Genetics accounts for 25-50% of the variance in VO2max
A typical world-class distance runner has a VO2max of ~85ml/kg/min.
Fill in the blank: Oxygen delivery is mainly determined by _______.
[cardiac output]
Fill in the blank: VO2max is primarily limited by _______.
[stroke volume]
True or False: A VO2max greater than 20ml/kg/min is an indication for lung surgery.
False
A VO2max < 10ml/kg/min or <40% predicted indicates ‘NO’ for surgery.
What is the impact of training on mitochondrial enzymes and VO2max?
- 2.2-fold increase in mitochondrial enzymes
- Only ~20-40% increase in VO2max
Individuals with similar VO2max can show a two-fold range in mitochondrial enzymes.
What is the significance of lactate threshold in endurance performance?
Ability to sustain a high percentage of VO2max over the race time
High lactate threshold indicates better endurance.
