Final answer:
Percent saturation of hemoglobin in a patient's blood is a direct indicator of tissue oxygen extraction.
Step-by-step explanation:
The percentage of hemoglobin sites occupied by oxygen in a patient's blood, known as percent saturation, is a direct indicator of tissue (muscle) oxygen extraction from the blood.
During intense muscle activity, oxygen is rapidly used by muscle cells to produce ATP, resulting in a lower partial pressure of oxygen in the muscle tissue. This lower partial pressure encourages a greater dissociation of oxygen molecules from hemoglobin, allowing them to enter the muscles for energy production.
Therefore, percent saturation of hemoglobin provides important information about tissue oxygenation and can be used to assess the level of athletic conditioning and certain medical conditions.