Lecture 20 - What Limits VO2max?

Question 1

what are the 5 possible sights of VO2max limitation?

Answer 1

1. pulmonary function
2. cardiac output
3. O2 carrying capacity of blood
4. muscle diffusion
5. skeletal muscle metabolic factors

Question 2

what is the limitation of pulmonary function?

Answer 2

• VE
• healthy lungs are overbuilt
• lungs are capable of holding even more during intense exercise
• O2 should be around 70 in healthy individuals
• this is the ability for the lungs to transport O2 from the alveoli to pulmonary capillaries
• those with COPD have inadequate ventilation of alveoli

Question 3

what is the limitation of cardiac output?

Answer 3

• if the heart could pump more blood per minute
• this is the main limitation
• if the muscle could get more oxygen, it would use more oxygen
• stroke volume is the limiting factor

Question 4

what is the limitation of O2 carrying capacity of blood?

Answer 4

• the amount of hemoglobin in the blood
• does the concentration of Hb increase with blood doping

Question 5

what is the limitation of muscle diffusing capacity?

Answer 5

• ability of the muscle to extract O2 from blood to muscle mitochondria
• affected by distance between capillary and mitochondria, contact area and pressure gradient between mitochondria and capillary.

Question 6

what is the limitation of skeletal muscle metabolic factors?

Answer 6

• amount of mitochondria may be the limiting factor
• untrained individuals may not have enough mitochondria, trained individuals may have delivery issues