Maximal oxygen uptake (VO2 Max)

What is VO2 Max?

The sum of all the bodies systems use of oxygen

What is Fick’s equation?

VO2 = HR x SV x (AVO2 difference)

Using Fick’s equation, what factors that increase cardiac output can affect VO2?

• Increased capillary number

• Increased mitochondria

• Increased myoglobin stores

All these factors increase the amount of oxygen extracted from the blood to the muscle

Using Fick’s equation, what factors that increase cardiac output can affect VO2?

• Increased HR and SV

• Increased preload and decreased afterload

• Increased SNS activity

• Catecholamines

What does the bilateral leg VO2 Max study show?

• During bilateral leg extensions there was less oxygen extraction at the muscles when compared to unilateral extensions

• This is because the heart can’t deliver the blood to each leg as well at the same time

What does the mitochondrial VO2 Max study show?

• When sedentary participants exercised their mitochondrial enzymes increased by 2.2x, but only a 20-40% increase in VO2 Max

• This shows that the heart can’t deliver as much oxygen as expected, so its a central issue

What does the blood volume VO2 study show?

• An increase in blood volume caused an increase in VO2 max

• This proves its more about central adaptations, and less about the muscle oxygen extractability

What did the dog study on VO2 Max show?

• The pericardium of the dogs heart was removed allowing it to inflate and contract more

• This saw an increase in VO2 max, showing the central limitations on VO2 Max

How is relative VO2 Max values calculated?

The absolute VO2 Max score (e.g 4L/min) is divided by the body mass (80kg)

4L / 80kg = 50mL/kg/min

What is the link between age and VO2 Max?

After the age of 25 there is a 1% reduction per year

How much does genetics account for VO2 max?

25-50% of a persons VO2 max

What are some essentials for a VO2 Max test?

• Use of an incremental exercise test to exhaustion

• Cause exhaustion between 8-12 minutes due to shorter protocols causing peripheral fatigue, and longer protocols causing exhaustion due to duration

• Use large muscle groups to stress out central components before local muscle failure

What is the primary criteria to recognise someone has hit their VO2 Max?

• Plateau in VO2 despite intensity increasing

• This can be seen by an increase of less than 2mL/kg/min

What is the secondary criteria to recognise someone has hit their VO2 Max?

• Heart rate within 90% of age predicted maximum (220 - age)

• Blood lactate concentration over 8 mmo/L

• RER of 1.15 or above

What does VO2 Peak mean?

Indicates that peak oxygen uptake was reached in the specific test, but might not be the true VO2 Max