Certified Personal Trainer (NSCA) Practice Exam 2026 – Complete Prep Guide

The term "aerobic threshold" refers to the exercise intensity at which the body transitions from primarily using fat as its energy source to utilizing carbohydrates as the intensity increases. This threshold represents a critical point in exercise physiology because it indicates a change in the body's metabolism and is closely linked to endurance performance.

During lower-intensity activities, the body predominantly burns fat for energy due to sufficient oxygen availability. However, as exercise intensity increases, oxygen becomes less adequate for fat oxidation, prompting the body to shift to carbohydrates, which can be metabolized more quickly. Understanding this threshold helps trainers and athletes design appropriate training programs to enhance aerobic capacity and improve overall performance. This focus on energy source utilization is essential for endurance training and optimizing athletic performance, particularly in events that require sustained effort.