Respiratory adaptation is the specific change that the

respiratory system The respiratory system (also respiratory apparatus, ventilatory system) is a biological system consisting of specific organs and structures used for gas exchange in animals and plants. The anatomy and physiology that make this happen varies grea ...

undergoes in response to the demands of

physical exertion Exertion is the physical or perceived use of energy.Newton's Third Law, Elert, Glenn. “Forces.” ''Viscosity – The Physics Hypertextbook'', physics.info/newton-first/. Exertion traditionally connotes a strenuous or costly ''effort'', resultin ...

. Intense physical exertion, such as that involved in fitness training, places elevated demands on the respiratory system. Over time, this results in respiratory changes as the system adapts to these requirements. These changes ultimately result in an increased exchange of

oxygen Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as wel ...

and

carbon dioxide Carbon dioxide (chemical formula ) is a chemical compound made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature. In the air, carbon dioxide is transpar ...

, which is accompanied by an increase in

metabolism Metabolism (, from el, μεταβολή ''metabolē'', "change") is the set of life-sustaining chemical reactions in organisms. The three main functions of metabolism are: the conversion of the energy in food to energy available to run cell ...

. Respiratory adaptation is a physiological determinant of peak endurance performance, and in elite athletes, the pulmonary system is often a limiting factor to exercise under certain conditions.

Neural control

Respiratory adaptation begins almost immediately after the initiation of the physical

stress Stress may refer to: Science and medicine * Stress (biology), an organism's response to a stressor such as an environmental condition * Stress (linguistics), relative emphasis or prominence given to a syllable in a word, or to a word in a phrase ...

associated with exercise. This triggers signals from the

motor cortex The motor cortex is the region of the cerebral cortex believed to be involved in the planning, control, and execution of voluntary movements. The motor cortex is an area of the frontal lobe located in the posterior precentral gyrus immediately a ...

that stimulate the respiratory center of the

brain stem The brainstem (or brain stem) is the posterior stalk-like part of the brain that connects the cerebrum with the spinal cord. In the human brain the brainstem is composed of the midbrain, the pons, and the medulla oblongata. The midbrain is conti ...

, in conjunction with feedback from the proprioreceptors in the muscles and joints of the active limbs.

Breathing rate

With higher intensity training,

breathing rate The respiratory rate is the rate at which breathing occurs; it is set and controlled by the respiratory center of the brain. A person's respiratory rate is usually measured in breaths per minute. Measurement The respiratory rate in humans is mea ...

is increased in order to allow more air to move in and out of the lungs, which enhances gas exchange.

Endurance training Endurance training is the act of exercising to increase endurance. The term endurance training generally refers to training the aerobic system as opposed to the anaerobic system. The need for endurance in sports is often predicated as the need o ...

typically results in an increase in the respiration rate.

Lung capacity

With adaptation,

lung capacity Lung volumes and lung capacities refer to the volume of air in the lungs at different phases of the respiratory cycle. The average total lung capacity of an adult human male is about 6 litres of air. Tidal breathing is normal, resting breathin ...

increases, allowing a greater quantity of air to move in and out. Endurance training typically results in an increase in

tidal volume Tidal volume (symbol VT or TV) is the volume of air moved into or out of the lungs during a normal breath. In a healthy, young human adult, tidal volume is approximately 500 ml per inspiration or 7 ml/kg of body mass. Mechanical vent ...

Respiratory muscles

Muscles involved in respiration, including the diaphragm and

intercostal muscles Intercostal muscles are many different groups of muscles that run between the ribs, and help form and move the chest wall. The intercostal muscles are mainly involved in the mechanical aspect of breathing by helping expand and shrink the size ...

, increase in strength and endurance. This results in an improved ability to breathe in more air, for longer amounts of time with less fatigue.

Aerobic training Aerobic exercise (also known as endurance activities, cardio or cardio-respiratory exercise) is physical exercise of low to high intensity that depends primarily on the aerobic energy-generating process. "Aerobic" is defined as "relating to, inv ...

typically improves the endurance of respiratory muscles, whereas anaerobic training tends to increase the size and strength of respiratory muscles.

Lung capillaries

Exercise increases the

vascularization Angiogenesis is the physiological process through which new blood vessels form from pre-existing vessels, formed in the earlier stage of vasculogenesis. Angiogenesis continues the growth of the vasculature by processes of sprouting and splitting ...

of the lungs. This allows the more blood flow in and out of the lungs. This enhances the uptake of oxygen, since there is greater surface area for blood to bind with

haemoglobin Hemoglobin (haemoglobin BrE) (from the Greek word αἷμα, ''haîma'' 'blood' + Latin ''globus'' 'ball, sphere' + ''-in'') (), abbreviated Hb or Hgb, is the iron-containing oxygen-transport metalloprotein present in red blood cells (erythrocyte ...

Alveoli

Respiratory adaptation results an increase in the number of

alveoli Alveolus (; pl. alveoli, adj. alveolar) is a general anatomical term for a concave cavity or pit. Uses in anatomy and zoology * Pulmonary alveolus, an air sac in the lungs ** Alveolar cell or pneumocyte ** Alveolar duct ** Alveolar macrophage * ...

, which enables more gas exchange to occur. This is coupled with an increase in alveolar oxygen tension.

References

{{Reflist Respiratory physiology Exercise physiology