VO2 MAX & TRAINING ADAPTATIONS

Oxygen Consumption (VO2)• The amount of o2 taken up and consumed

by the body for metabolic processes.• Equal to amount of inspired air minus

amount of expired air• VO2 is proportional to workload• Measured by a metabolic cart in a lab

environment

..cont.

• The maximal rate of oxygen consumption would occur at max HR, SV.

• VO2 max is the maximal amount of O2 that can be taken in and used for the metabolic production of ATP during exercise

Limiting factors to VO2• The Respiratory System: Inadequate ventilation and

oxygen diffusion limitations• The cardiovascular system: Inadequate blood flow;

inadequate oxygen-carrying capacity (Q likely the biggest limiting factor)

• Energy systems: Lack of mitochondria• Heredity: Accounts for between 25% and 50% of the

variance in VO2 Max values.• Age: Related decreases in VO2 Max might partly

result from an age-related decrease in activity levels.• Gender: Plays a small role (10%) in the VO2 Max

values of male and female endurance athletes.

Oxygen Deficit and EPOCOxygen Deficit and EPOC

Con’t

• Oxygen deficit: Difference between the O2 required to perform a task and the O2 consumed before reaching steady state (sub-maximal)

• Trained individuals reach this state earlier than non-trained individuals.

EPOC

• Excess Post-exercise Oxygen Consumption: The extra oxygen required to replenish oxygen to the various systems that were taxed during the exercise.

• Eg: Refilling phosphocreatine reserves, replenishing O2 in blood and tissues, lowering breathing rate, lowering body temp. and increasing blood lactate removal.

• Active recovery can aid in the removal of blood lactate.

Physiological Adaptations Due Physiological Adaptations Due to Endurance Trainingto Endurance Training

Cardiovascular Adaptations From Aerobic Training

• Increased cardiorespiratory endurance• Increased muscular endurance• Decreased VO2 at rest and submaximal exercise• Increased VO2 Max• Increased heart weight, volume, and chamber size

– Increased left ventricle wall thickness “athletes heart”– Increased left ventricle EDV– Increased blood plasma

• Increased Stroke Volume

Cardiovascular Adaptations From Aerobic Training

• Decreased Resting Heart Rate • Decreased submaximal heart rate• Decreased maximum heart rate of elite athletes

– if your heart rate is too fast the period of ventricular filling is reduced and your stroke volume might be compromised.

– the heart expends less energy by contracting less often but more forcibly than it would by contracting more often.

• Decreased Heart Rate Recovery

Cardiovascular Adaptations From Aerobic Training

• Maintained cardiac output at rest and submaximal exercise

• Increased cardiac output during maximal exercise• Increased blood flow to the muscles

– increased capillarization of trained muscles– greater opening of existing capillaries in trained muscles– more effective blood redistribution– increased blood volume– decreased blood viscosity & increased oxygen delivery

• Decreased resting blood pressure – from increased blood flow

Cardiovascular Adaptations From Aerobic Training

• Increased blood volume (blood plasma) and is greater with more intense levels of training– increased plasma proteins which help

retain blood fluid– increased red blood cell volume– decreased blood viscosity

Respiratory Adaptations From Aerobic Training

• Respiratory system functioning usually does not limit performance because ventilation can be increased to a greater extent than cardiovascular function.

• Slight increase in Total lung Capacity• Slight decrease in Residual Lung Volume• Increased Tidal Volume at maximal exercise

levels• Decreased respiratory rate and pulmonary

ventilation at rest and at submaximal exercise– (RR) decreases because of greater pulmonary

efficiency• Increased respiratory rate and pulmonary

ventilation at maximal exercise levels– from increased tidal volume

Respiratory Adaptations From Aerobic Training

• Unchanged pulmonary diffusion at rest and submaximal exercise.

• Increased pulmonary diffusion during maximal exercise.– from increased circulation and

increased ventilation– from more alveoli involved

during maximal exercise• Increased A-VO2 difference

especially at maximal exercise.

Metabolic Adaptations From Aerobic Training

• Lactate threshold occurs at a higher percentage of VO2 Max.– from a greater ability to clear lactate from the muscles– from an increase in skeletal muscle enzymes

• Decreased Respiratory Exchange Ratio (ratio of carbon dioxide released to oxygen consumed)– from a higher utilization of fatty acids instead of carbo’s– however, the RER increases from the ability to perform at

maximum levels of exercise for longer periods of time because of high lactate tolerance.

• Increased resting metabolic rate• Decreased VO2 during submaximal exercise

– from a metabolic efficiency and mechanical efficiency

Metabolic Adaptations From Aerobic Training

• Large increases in VO2 Max– in mature athletes, the highest attainable VO2 Max is

reached within 8 to 18 months of heavy endurance training.

– VO2 Max is influenced by “training” in early childhood.• from increased size and number of mitochondria• from increased blood volume, cardiac output & O2

diffusion• from increased capillary density

Physiological Adaptations Due Physiological Adaptations Due to Endurance Trainingto Endurance Training