Final answer:
The phrase about the rear rank breathing hard typically refers to forced breathing or hyperpnea, which is a deep and fast breathing mode during exercise, affecting the functional residual capacity of the lungs.
Step-by-step explanation:
When referring to the phrase 'what makes the rear rank breathe so hard,' it usually pertains to the concept of forced breathing or hyperpnea, which is a mode of breathing that occurs during activities like exercise. This type of breathing involves muscle contraction for both inspiration and expiration. It's an increase in the depth and rate of breathing compared to at rest. The functional residual capacity (FRC), which is the sum of expiratory reserve volume (ERV) and residual volume (RV), is the amount of air remaining in the lungs after a tide expiration and can be affected during exercise as the breathing pattern changes to meet the body's increased demand for oxygen.