ACE Personal Trainer Practice Exam 2025 - Free Personal Trainer Practice Questions and Study Guide

The point at which exercise intensity becomes unsustainable due to lactate accumulation is known as VT2, or the second ventilatory threshold. At VT2, the body can no longer efficiently clear the lactate produced from anaerobic metabolism, leading to a progressive accumulation of lactate in the bloodstream. This accumulation correlates with the point at which the exercise intensity increases to levels that cannot be sustained for prolonged periods.

VT1, or the first ventilatory threshold, typically represents a level of exercise where the body can still clear lactate effectively, indicating a shift to more aerobic metabolism. While resting levels and maximum heart rate are relevant to understanding overall fitness and exercise capacity, they do not specifically indicate the point of lactate accumulation and sustainability in the context of exercise intensity.

Thus, VT2 signifies that threshold where anaerobic activity predominates, making it the correct choice for identifying the unsustainable intensity due to lactate buildup.