Chronic Adaptations to Training

This section covers the chronic adaptations of the cardiovascular, respiratory, and muscular systems to aerobic, anaerobic, and resistance training, and how these adaptations improve performance.

I. Cardiovascular System Adaptations

A. Adaptations to Aerobic Training

• Heart Size and Volume:
  • Increased left ventricle volume. This allows for greater filling with blood during diastole.
  • Slight increase in the thickness of the left ventricular wall.
• Stroke Volume (SV):
  • Increased stroke volume at rest, during submaximal exercise, and maximal exercise. This is due to the increased left ventricle volume and improved contractility.
• Cardiac Output (Q):
  • Increased maximal cardiac output. While resting cardiac output remains relatively unchanged, the increase during exercise is significant due to the increased stroke volume.
  • $Q = SV \times HR$
• Heart Rate (HR):
  • Decreased resting heart rate. The heart becomes more efficient, requiring fewer beats to pump the same amount of blood.
  • Decreased submaximal heart rate.
  • Maximal heart rate remains relatively unchanged or may slightly decrease.
• Blood Volume:
  • Increased blood volume, primarily due to an increase in plasma volume. This leads to:
    • Increased venous return.
    • Improved thermoregulation.
    • Increased oxygen carrying capacity.
• Blood Vessels:
  • Increased capillarisation around the heart muscle (myocardium) and skeletal muscles. This improves oxygen delivery and waste removal.
  • Improved vasodilation and vasoconstriction control.
• Blood Pressure:
  • Decreased resting blood pressure in individuals with hypertension.
  • Submaximal exercise blood pressure may be lower.

B. Adaptations to Anaerobic Training

• Heart Size:
  • Increased thickness of the left ventricular wall, primarily in response to resistance training. This is a pressure overload adaptation, making the heart stronger.
• Blood Pressure:
  • May lead to increases in resting blood pressure, particularly with heavy resistance training.

C. Impact on Performance

• VO2 Max: Increased VO2 max due to enhanced oxygen delivery and utilization.
• Lactate Inflection Point (LIP): Increased exercise intensity at which the LIP occurs. This means the athlete can work at a higher intensity before lactate accumulates rapidly.

KEY TAKEAWAY: Aerobic training enhances the heart’s ability to pump blood and deliver oxygen, while anaerobic training strengthens the heart muscle.

II. Respiratory System Adaptations

A. Adaptations to Aerobic Training

• Lung Volumes and Capacities:
  • Increased total lung capacity (TLC).
  • Increased vital capacity (VC).
  • Increased tidal volume (TV) during maximal exercise.
  • Residual volume may also increase slightly.
• Pulmonary Ventilation:
  • Increased maximal pulmonary ventilation (the amount of air breathed in and out per minute). This is due to increased tidal volume and breathing frequency.
  • Improved efficiency of ventilation.
• Alveolar-Capillary Diffusion:
  • Increased surface area for gas exchange at the alveolar-capillary interface.
  • Improved diffusion capacity of oxygen and carbon dioxide.
• Respiratory Muscle Strength and Endurance:
  • Increased strength and endurance of the diaphragm and other respiratory muscles.

B. Adaptations to Anaerobic Training

• Fewer significant structural adaptations compared to aerobic training. However, there may be:
  • Improved strength and endurance of respiratory muscles.
  • Enhanced buffering capacity of the blood, helping to manage the increased acidity from anaerobic metabolism.

C. Impact on Performance

• Increased VO2 max due to improved oxygen uptake.
• Reduced feelings of breathlessness during exercise.
• Improved ability to sustain high-intensity efforts.

EXAM TIP: When discussing respiratory adaptations, focus on how structural and functional changes improve oxygen uptake and delivery.

III. Muscular System Adaptations

A. Adaptations to Aerobic Training

• Capillarisation:
  • Increased capillarisation around muscle fibres, especially slow-twitch fibres. This improves oxygen and nutrient delivery, and waste removal.
• Mitochondria:
  • Increased number and size of mitochondria within muscle cells. This enhances the capacity for aerobic ATP production.
• Myoglobin:
  • Increased myoglobin content in muscle cells. Myoglobin facilitates oxygen transport within the muscle cell.
• Fuel Storage:
  • Increased storage of glycogen and triglycerides within muscle cells. This provides readily available fuel for aerobic metabolism.
• Fibre Type Adaptations:
  • Increased oxidative capacity of both slow-twitch (Type I) and fast-twitch (Type II) muscle fibres.
  • Potential shift in fibre type characteristics, with fast-twitch fibres becoming more resistant to fatigue.
• Enzymes:
  • Increased activity of aerobic enzymes involved in the Krebs cycle and electron transport chain.

B. Adaptations to Anaerobic Training

• Muscle Hypertrophy:
  • Increased size of fast-twitch (Type II) muscle fibres.
• Fuel Storage:
  • Increased storage of ATP, PC, and glycogen within muscle cells.
• Glycolytic Enzymes:
  • Increased activity of glycolytic enzymes, enhancing the capacity for anaerobic ATP production.
• Lactate Tolerance:
  • Increased buffering capacity of muscle cells, allowing for greater tolerance of lactate accumulation.

C. Adaptations to Resistance Training

• Neural Adaptations:
  • Increased motor unit recruitment.
  • Increased rate of firing of motor units.
  • Improved synchronisation of motor unit firing.
  • Decreased co-contraction of antagonist muscles. These adaptations contribute to increased strength and power, particularly in the early stages of resistance training.
• Muscle Hypertrophy:
  • Increased size of muscle fibres (both Type I and Type II, but primarily Type II). This is due to an increase in the size and number of myofibrils.
• Connective Tissue:
  • Increased strength of tendons and ligaments.
• Bone Density:
  • Increased bone density.

D. Impact on Performance

• VO2 Max: Aerobic adaptations contribute to increased VO2 max.
• Lactate Inflection Point (LIP): Aerobic and anaerobic adaptations contribute to an increased LIP.
• Speed and Force of Muscular Contraction: Anaerobic and resistance training adaptations increase the speed and force of muscular contraction.
• Lactate Tolerance: Anaerobic training adaptations increase lactate tolerance.

COMMON MISTAKE: Students often confuse acute and chronic adaptations. Remember that chronic adaptations are long-term changes resulting from consistent training.

IV. Summary Table of Chronic Adaptations

STUDY HINT: Create flashcards to memorize the specific adaptations in each system for different types of training.

V. Reversibility of Adaptations

• Training adaptations are reversible. Detraining (cessation of training) leads to a gradual decline in fitness.
• The rate of detraining varies depending on the adaptation and the individual.
• Cardiovascular adaptations tend to decline more rapidly than muscular adaptations.

VCAA FOCUS: VCAA often asks questions that require you to link specific training methods to the chronic adaptations they elicit and how these adaptations improve performance in a given sport or activity.