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

Type 1 muscle fibers, also known as slow-twitch fibers, are primarily utilized during endurance activities that require sustained effort over a longer period. These fibers are characterized by their ability to resist fatigue, relying on aerobic metabolism for energy. Activities such as walking and swimming engage these fibers because they involve moderate, steady-state movements that require endurance rather than explosive power.

Walking, for instance, is a low-intensity activity that can be maintained for extended durations, allowing Type 1 fibers to work efficiently. Similarly, swimming requires a continuous, rhythmic effort, which is ideal for the aerobic capacity of slow-twitch fibers. Both activities emphasize endurance over speed or power, aligning perfectly with the functional capacity of Type 1 muscle fibers.

In contrast, the other activities listed involve higher intensity and explosive efforts that primarily engage Type 2 muscle fibers, which are more suited for quick, powerful movements but fatigue faster. Thus, the correct answer reflects activities that predominantly use the endurance capabilities of Type 1 fibers.