RESPONSE OF THE RESPIRATORY SYSTEM TO EXERCISE
Consisting of a series of body parts including the lungs, diaphragm and nasal cavity, the respiratory system is responsible for transporting oxygen and carbon dioxide to and from muscles and tissues. During exercise, the respiratory system increases to meet the demands of the working muscles. The respiratory system also uses the cardiovascular system — heart, blood and blood vessels — to transport oxygen and carbon dioxide.
VENTILATION / BREATHING RATE
Breathing rates increase with higher intensity training (this is more an adaptation from anaerobic fitness and muscular endurance training or higher intensity aerobic fitness training). This enables more air to move in and out of the lungs enhancing gas exchange.
LUNG CAPACITY/ VOLUME
Lungs increase their ability to expand enabling a greater quantity of air to move in and out (this is a similar adaptation to the increase in stroke volume in the cardiovascular system).
The strength and endurance of the diaphragm and intercostal muscles improves. This results in an improved ability to breathe in more air, for longer with less fatigue.
Aerobic training tends to improve the endurance of respiratory muscles
Anaerobic training tends to increase the size and strength of respiratory muscles
CAPILLARISATION IN THE LUNGS
More capillaries are formed in the lungs over time allowing more blood to flow in and out of the lungs. This improves the uptake of oxygen as there is a greater surface area for blood to bind with haemoglobin.
The numbers of alveoli in the lungs increase to enable more gas exchange to occur.
The exchange of oxygen and carbon dioxide improves as the gradient between each becomes larger. This occurs because the more oxygen used in the tissues and the more carbon dioxide produced creates a larger difference/gradient between the blood and tissues.
Aerobic fitness training tends to improve the efficiency of the body’s tissues at absorbing O2 and removing CO2, while anaerobic fitness and muscular endurance training tends to improve the capacity for this gas exchange.
During exercise, your adrenal gland increases production of adrenaline and noradrenaline that directly affect the heart and the ability to transport oxygen and carbon dioxide throughout the body. The hormones then directly influence the sympathetic nerves to stimulate the heart to beat stronger for increased stroke volume and faster for increased heart rate and an overall increase in cardiac output.
To meet the increasing oxygen demands from the working muscles, additional oxygen must be transported through the blood vessels. During exercise, the sympathetic nerve stimulates the veins to constrict to return more blood to the heart. This blood is carrying carbon dioxide from the muscles and can increase the total stroke volume of the heart by 30 to 40 percent.
With an increased amount of oxygen and carbon dioxide transport, your respiratory rate — rate of breathing — also increases. This increase is also influenced by the sympathetic nerves stimulating the respiratory muscles to increase the rate of breathing. At rest, your respiratory rate is about 14 per minute but can increase to 32 per minute during exercise. The increased respiration rate allows more oxygen to reach the lungs and blood to be delivered to the muscles.
LONG TERM RESPONSE
A long-term respiratory system response to exercise involves several physiological adaptations. These adaptations ultimately result in an increase in overall efficiency of the respiratory system to gather, transport and deliver oxygen to the working muscles. The long-term respiratory function is commonly measured with a VO2 max test that calculates your body’s ability for oxygen consumption during maximal exercise. Through exercise and training, the effectiveness of the respiratory system and VO2 max improve.
RESPIRATORY PHYSIOLOGY: ADAPTATIONS TO HIGH-LEVEL EXERCISE:
Most exercise scientists would agree that the physiological determinants of peak endurance performance include the capacity to transport oxygen to the working muscle, diffusion from the muscle to the mitochondria, energy production and force generation, all influenced by signals from the central nervous system. In general, the capacity of the pulmonary system far exceeds the demands required for ventilation and gas exchange during exercise. Endurance training induces large and significant adaptations within the cardiovascular, musculoskeletal and haematological systems. However, the structural and functional properties of the lung and airways do not change in response to repetitive physical activity and, in elite athletes, the pulmonary system may become a limiting factor to exercise at sea level and altitude. As a consequence to this respiratory paradox, highly trained athletes may develop intrathoracic and extrathoracic obstruction, expiratory flow limitation, respiratory muscle fatigue and exercise-induced hypoxaemia. All of these maladaptations may influence performance.