Which of the following types of muscle fibers are best adapted for prolonged contraction such as standing all day?

A) uninucleated fibers

B) striated fibers

C) fast fibers

D) slow fibers

E) intermediate fibers

The correct answer is: D) slow fibers

There are two different fibers in muscle:

• Slow twitch muscle fibers: Their main characteristic is that their contraction is slow, but keeps going for a long time. Suitable for long distance running, cycling or standing all day.

• Fast twitch muscle fibers: These fibers contract quickly, but rapidly get tired. Fast fibers are for rapid movements like jumping or sprinting.

Muscles in our body are usually made of mixture of both slow and fast fibers.