Final answer:
Factors affecting maximal inspiratory or expiratory pressures include the type of mouthpiece used, perioral leaks, time of day tested, and the training effect. Airway resistance impacts breathing by changing the ease with which air can move through the airways, with increased resistance making respiration more difficult.
Step-by-step explanation:
The variations in results of maximal inspiratory or expiratory pressures can be influenced by several factors. Using different types of mouthpieces may affect the measurements as each might offer varying resistance or fit.
Perioral leaks, where air escapes around the mouthpiece, would reduce the pressure measurements as not all the inspired or expired air goes through the meter.
The time of day a person is tested can also influence the results as lung function may vary due to natural circadian rhythms and physiological changes throughout the day.
Lastly, the training effect refers to the potential improvement in test results due to repeated measures, as subjects might become more adept at the test technique over time.
Airway resistance is a crucial factor that influences breathing. It is determined by the size of the airway and can be illustrated by the formula F = ΔP/R, where F is the flow rate, ΔP is the pressure difference, and R is the resistance. Increased resistance such as in conditions like asthma can lead to entrapped air in the lungs and make breathing difficult.