The respiratory system experiences an increase in breathing rate in direct response to the intensity of the exercise performed. According to PT Direct, breathing rates can increase up to 50 breaths per minute during exercise. That is 35 breaths per minute over the normal resting rate of 15 breaths per minute.
According to PT Direct, the two main functions of the respiratory system are to provide oxygen to body tissues and to rid the body of carbon dioxide. When high demand is placed on the respiratory system through exercise, the ventilation must increase by taking in a higher quantity of oxygen during inhalation. PT Direct explains that as exercise intensifies, ventilation must increase to meet the demands of higher oxygen needs placed on the body.
When exercise becomes overly intense, the respiratory system can reach a point where it can no longer continue to increase ventilation rates. At this point, the respiratory system takes longer to collect the oxygen that is needed to catch back up with the body's oxygen demand. This is why after strenuous exercise a person's breathing rate often remains elevated for 10 to 20 minutes post-workout, according to PT Direct.
It is recommended by Peak Fitness to breathe through the nose, not the mouth, during and after exercise. Breathing through the nose creates nitrous oxide which increases the lung's oxygen-absorbing capability and helps lower blood pressure post-workout. The benefits of nitrous oxide are lost when breathing through the mouth, according to Peak Fitness.