B2 Training and the Pulmonary System

B.2.1  Define total lung capacity, vital capacity, tidal volume and ventilation rate

Total lung capacity:  Volume of air in the lungs after a maximum inhalation

Vital capacity:  Maximum volume of air that can be exhaled after a maximum inhalation

Tidal volume:  Volume of air taken in or out with each inhalation or exhalation

Ventilation rate:  Number of inhalations or exhalations per minute

Overview of Different Types of Lung Capacity for a Typical Healthy Male

Lung capacity

B.2.2  Explain the need for increases in tidal volume and ventilation rate during exercise

  • During exercise, oxygen is consumed by the respiring muscles and carbon dioxide is produced as a by-product
  • Thus the rate of gas exchange within alveoli needs to increase in order to maintain the concentration gradients needed to continue cell respiration
  • Increasing levels of CO2 in the blood are detected by chemosensors in the walls of the arteries which trigger the breathing centre of the brainstem
  • Fresh air (high O2 levels, low CO2 levels) is exchanged with stale air (low O2 levels, high CO2 levels) in the lungs
  • Increasing the rate of gas exchange may be achieved in one of two ways:
    • Increasing tidal volume (deeper breaths allows more air into the lungs to be exchanged)
    • Increasing ventilation rate (a greater frequency of breaths allows a more continuous exchange of gases)

B.2.3  Outline the effects of training on the pulmonary system, including changes in ventilation rate at rest, maximum ventilation rate and vital capacity

  • Ventilation rate at rest can be reduced from about 14 to 12 bpm (breaths per minute)
  • Maximum ventilation rate can be increased from about 40 to 45 bpm or more
  • Vital capacity may increase slightly
  • General dilation of blood capillaries around the alveoli resulting in increased efficiency of gas exchange
  • Strengthening of the muscles used for ventilation (diaphragm and intercostals)