Endurance Performance and VO2 Max

Endurance Performance and VO2 Max

Factors Limiting VO2 Max

  • The lecture will cover factors limiting VO2 max, the role of the heart, oxygen supply, brain limitations, and the role of lactate.
  • Content covered up to the end of the lecture will be on the midterm.
  • VO2 max is the maximum amount of energy one's body can use, typically during exercise.

Overload Principle

  • Increases in endurance occur due to systematic and progressive exercise:
    • Frequency
    • Intensity
    • Duration
  • These factors cause adaptation (FIT principle).
  • Endurance is the ability to maintain force, power, and speed.

VO2 Max and Aerobic Energy Production

  • VO2 max is the maximum capacity for aerobic energy production.
  • Glycolysis is anaerobic (doesn't need oxygen).
  • Oxidative phosphorylation in mitochondria requires oxygen (aerobic).
  • VO2 max depends on oxygen delivery, influenced by:
    • Altitude (oxygen scarcity)
    • Red blood cells (hemoglobin binds and delivers oxygen).
    • Muscle use of oxygen (mitochondria for ATP production).

Lactate Threshold

  • Lactate is produced from pyruvate (end product of glycolysis).
  • Everyone has a lactate threshold, beyond which the body can't handle more lactate.
  • Fast fatigable muscle fibers produce a lot of lactate.
  • Accumulation of lactate leads to fatigue.
  • Athletes in endurance races try to maximize their lactate threshold to sustain performance.

Movement Economy

  • Movement economy describes the energy used to maintain a specific velocity or power.
  • Efficient movement economy (longer levers, tapered legs, appropriate shoes) reduces energy needed.

Definition of VO2 Max

  • VO2 max is the point at which oxygen intake does not increase despite an increase in exercise intensity.

Archibald V. Hill's Study

  • Archibald V. Hill won the Nobel Prize in 1922 for his work on heat and mechanical work in muscles.
  • Hill's study measured oxygen intake versus running speed.
  • Oxygen intake increases with speed but plateaus at VO2 max.

Cardiac Output and VO2 Max

  • Blood circulation, powered by the heart, is essential for oxygen delivery.
  • There is a strong correlation between cardiac output and VO2 max.
  • The more blood the heart can pump, the higher the VO2 max.
  • A study from 1964 showed women's data lower than men's due to societal factors discouraging women from exercising.

Heart Rate, Stroke Volume, and VO2 Max

  • Heart rate has a linear relationship with % max VO2.
  • Max heart rate is age-related (Max Heart Rate=220−AgeMax\ Heart\ Rate = 220 - Age).
  • Stroke volume plateaus after about 40% max VO2.
  • Endurance training should focus on stroke volume rather than heart rate, as heart rate is largely age-dependent.

Analogy for Stroke Volume vs. Heart Rate

  • Waiting in line for a ride at Disneyland (Space Mountain).
  • Increasing spaceship size (stroke volume) is preferable to shortening the ride (heart rate).

Hypertrophy of the Heart Due to Endurance Training

  • Endurance training increases heart muscle size (hypertrophy).
  • A trained heart can accommodate more blood (e.g., 100 ml vs. 70 ml in an untrained heart).
  • At rest, a trained heart requires fewer beats per minute, resulting in a lower resting heart rate (around 50 bpm compared to 70 bpm in untrained individuals).
  • Increased cardiac output due to higher ejection fraction.

Oxygen Transfer and VO2 Max

  • Experiment: Subjects run on a treadmill while breathing:
    • 15% carbon monoxide
    • Normal air (20% oxygen)
    • High oxygen (50% oxygen)
  • Results: Increased oxygen in the blood increases VO2 max.

High Altitude Training

  • Training at high altitude lowers oxygen tension, signaling the body to produce more red blood cells.
  • Increased red blood cells improve VO2 max and performance.

Blood Doping

  • Involves drawing blood, preserving red blood cells, and re-injecting them before competition.
  • Increases red blood cell count and oxygen transport.
  • Considered illegal.

Erythropoietin (EPO) Hormone Therapy

  • EPO is a hormone produced in the kidney that stimulates red blood cell production.

Ways to Increase Red Blood Cell Count

  1. Train at high altitude.
  2. Blood doping.
  3. Erythropoietin hormone therapy.

Eero Mäntyranta: Genetic Advantage

  • Finnish athlete with multiple Olympic and World Championship medals.
  • Had a genetic mutation in the erythropoietin receptor (EPOR), leading to naturally higher red blood cell production.
  • This gave him a significant advantage.
  • Raises questions about fairness in sports and how to address genetic advantages.