3 - VO2 Max

VO2 Max

Maximum o2 uptake

Different Aerobic Capacities

1. Absolute value is different to relative value (depends on muscle)

2. More trained skeletal muscle, better utilisation of o2

Absolute VO2 Max

the total volume of oxygen uptake (litres/min) regardless of body size.

Relative VO2 Max

millilitres of O₂ per kilogram body-weight per minute (mL·kg⁻¹·min⁻¹).

Why Use VO2 Max as a Measure For Aerobic Capacity

Sum of all these systems

Aerobic Contribution vs Exercise Duration

1. ATP-PCr System - 100m, 0-10s, use exisiting ATP stores

2. Glycolysis - 400m 

3. Aerobic System - 1500m

Energy Storages

1. Oxidation of fat - most amount of energy stored

• Limited amount of energy per time (can only run so fast)

2. Oxidation of Carbs - Medium amount of enrgy stored

3. Phosphocreatine - smallest amount of energy stored

• Lots of energy per time (run faster)

• Only lasts a short amount of time

4. Anaerobic glycolysis - lactate production

Fick Equation

VO2 Factors

1. Contractility - contract more vigorously

2. Preload - more blood returning to the heart from the peripheral

3. Afterload - resistance to which your heart has to contract

4. SNS - stress, constrict vessels to lo energy organs, dilate vessels to muscles

VO2 Max Depends On

1. Good CVS 

2. High CO

3. Oxidative capacity in skeletal muscles e.g. mitochondria, oxidative enzymes

Limiting Factor - O2 Delivery vs O2 Utilisation (Basset and Howley (2000)

ACUTE EXERCISE STUDY:

1. Shows its a central limitation (the muscle can absorb so much o2 during single leg it absorbs less during doble leg as not enough o2 is delivered by the heart)

2. Extraction should be the same, so heart delivery is the issue

LONGITUDINAL TRAINING STUDIES:

1. 2x capacity should also be 2x increase in VO2 max

2. Would expect individuals to have a higher VO2 Max

ctd

Dog Study (Stray-Gundersen et al. (1986)

1. Removed pericardium (lining of heart)

Absolute vs Relative VO2 Max Scores

Assessing fitness using VO2 Max

VO2 Max in Surgery

VO2 Max in Professional Athletes

Age + Training

1. After 25 = decrease 1% per year

2. Ageing causes more rapid decline

3. Maybe confounded by disease

Heredity

1. Genetics = 25-50% variation in VO2

2. Elite runner - 85 ml/kg/min

3. Deconditioned - 65/ml/kg/min

VO2 Max Determination: Protocol Design

Incremental Exercise Test To Exhaustion

Maximal oxygen uptake: Definition (ACSM / BASES guidelines) - PRIMARY CRITERIA

1. Primary criterion: Plateau in VO2 despite load/speed increase to next stage (Less than 2 mL/kg/min)

2. When aerobic plateaus - vo2 max primer parameter if exhaustion has been reached

• Energy may come from other sources e.g. anaerobic

Maximal oxygen uptake: Definition (ACSM / BASES guidelines) - SECONDARY CRITERIA

1. HR - within 90% of age predicted max (220-age)

2. Blood lactate concentration - over 8 mmol/L (indication of large contribution of anaerobic metabolism)

3. Respiratory exchange ratio (RER) - ( ሶVCO2/ ሶVO2) of 1.15 or above (indication of large contribution of anaerobic metabolism)#

1. Not all individuals show all criteria

VO2 Peak

Highest value recorded (when there’s no plataeu)

Other determinants of endurance performance

Summary