L5.1 VO2

Question 1

How is VO2 determined?

Answer 1

• VO2 levels determined from training (O2 delivery) and genetics
  
  • Maximal heritability = 51%

Question 2

How does VO2 vary with age, and what is the frailty threshold?

Answer 2

• Decreases Vo2 with age
• Frailty threshold = ~ 15% VO2 max
  
  • Below 15% → hard to do daily activities
    
    • ∴ physical activites beneficial for anti-aging

Question 3

What are the 4 factors limiting VO2 max?

Answer 3

• Respiration (Hb affinity for O2)
• Central circulation ([Hb] mainly)
• Peripheral circuits (blood flow - mainly influenced by capillary density)
• Metabolism (determined by mito levels)

Question 4

How does the leg oxidative capacity differ from the arms?

As such, how does it affect the VO2 max?

Answer 4

• ↑ Mito → ↑ oxidative capacity
• ↑ muscle mass → ↓O2 delivery due to inability to drop TPR as much (need to limit BF there)
  
  • Limits VO2 max

Question 5

How does VO2 affect Q?

Answer 5

↑ VO2 max → ↑ Q

Question 6

How do different concentrations of O2 affect VO2 max?

Answer 6

• ↓O2 supply (eg 15% supply) → ↓ desaturation & VO2 max (EIAH)
• ↑O2 supply (eg 26% supply) → Maintain saturation & ↑ VO2 max

Question 7

How does increase BV and blood doping affect VO2 max?

Answer 7

• ↑ BV → acute hypervolemia → ↑maximal SV & Q (mainly in untrained)
• Blood doping (EPO) → ↑ red cell mass → ↑ CaO2 carrying capacity
• ∴ ↑VO2 max

Question 8

What is the muscle diffusion capacity?

Answer 8

How well you can transfer O2 from HbO into muscle mito