C5–C7 Responses, Adaptations and Additional Factors GapFill

Altitude

Altitude refers to the height of an object or point in relation to sea level. As elevation increases,  air pressurewind speedpartial pressure of carbon dioxidetemperature decreases, which in turn decreases the partial pressure of oxygen available. This has obvious implications for exercise performance since the reduced availability of atmospheric oxygen means that, at the same breathing rate, there will be a lower partial pressure of oxygen at the  lungalveolimouthtrachea for gaseous exchange and thus less oxygen extraction taking place at the muscle. This reduction in the partial pressure of oxygen is known as  hyperoxiahypoxianormobariahyperbaria. 

Performance impairments don't usually occur until altitude reaches around 2,000 m, from which point any further increase in altitude results in an exponential impairment of exercise performance. At sea level the fraction of oxygen in inspired air is around  2116124%, whereas this value decreases to ~16% at 2,000 m and to ~12.5% at 4,000 m. Training at altitude is much more difficult, and athletes often have to reduce exercise intensity in the initial phase of training. It is also often accompanied by sickness due to the sudden changes in atmospheric pressure. At first, there is an increase in the athlete’s heart rate and ventilation rate to compensate for lower oxygen levels. As training becomes more habitual, the chronic lack of oxygen in the atmosphere forces the body to adapt.  White blood cellPlasmaRed blood cellExercise count increases, improving the body's oxygen-carrying capacity. This process is called   alterationacclimatisationadaptationambulation and can last for an extended period of time upon return to sea level, allowing the athlete to retain these benefits in upcoming competitions. Benefits can also be attained by simply living at high altitude. The use of altitude simulation chambers by many professional sporting teams improves the feasibility of this form of training.

Asthma

An additional factor to consider with the respiratory system is whether the individual suffers from a pulmonary condition. Asthma, which restricts the flow of air into the lungs, is a common example of such a condition. This is caused by the contraction and tightening of muscles surrounding the  skintracheamusclebronchioles, which should be relaxed in normal inspiration. This reduces oxygen delivery to the alveoli and thus impairs gaseous exchange and subsequent perfusion of oxygen in the body. Common symptoms include a tight chest, shortness of breath and wheezing. The severity of asthma can increase when air is cold and dry or contains dust particles, or the condition can be triggered by an allergy.