Humberto runs marathons. While running, he relies on his ______ muscles that are ______.
A) fast-twitch; aerobic
B) fast-twitch; anaerobic
C) slow-twitch; aerobic
D) slow-twitch; anaerobic

Question

Quizplus · Accepted Answer

During endurance events such as marathons, the body relies primarily on slow-twitch (Type I) muscle fibers, which are highly aerobic and fatigue-resistant. These muscle fibers utilize oxygen to efficiently produce energy for sustained periods of activity. In contrast, fast-twitch (Type II) muscle fibers are anaerobic and better suited for short bursts of intense activity, such as sprinting or weightlifting.

Humberto Runs Marathons