What is the approximate percentage of oxygen in exhaled air?

The approximate percentage of oxygen in exhaled air is around 16%. This is important to understand because it highlights the process of respiration. During inhalation, air enters the lungs, where oxygen is absorbed into the bloodstream. When exhaling, a significant portion of the oxygen is utilized by the body's tissues for metabolic processes, which leads to the lower percentage of oxygen in exhaled air.

Inhaled air typically contains about 21% oxygen, while exhaled air contains roughly 16%, indicating that approximately 5% of the oxygen has been consumed during the process of cellular respiration. This detail is crucial for fitness instructors to understand as it provides insights into how the body utilizes oxygen during physical activity and informs training programs and aerobic exercises that rely on effective oxygen consumption and delivery.