College of Massage Therapists of British Columbia (CMTBC) Practice Exam

Which type of skeletal muscle fiber is characterized by less fatigue and is suited for endurance activities?

1. Fast-twitch fibers

2. Slow-twitch fibers

3. Intermediate fibers

4. Hybrid fibers

The correct answer is: Slow-twitch fibers

The type of skeletal muscle fiber that is characterized by less fatigue and is particularly suited for endurance activities is slow-twitch fibers. These fibers are designed for prolonged activity and rely on aerobic metabolism to produce energy, allowing them to sustain muscle contractions over extended periods without tiring quickly. This makes them ideal for activities such as long-distance running, cycling, and other endurance sports. Slow-twitch fibers contain a rich supply of blood vessels, myoglobin, and mitochondria, which enhance their capacity for oxygen uptake and storage. This physiological makeup enables them to efficiently utilize oxygen to generate energy over time, leading to reduced fatigue compared to other fiber types. Fast-twitch fibers, in contrast, are more suitable for short bursts of high-intensity activity but tend to fatigue quickly due to their reliance on anaerobic metabolism. Intermediate fibers have characteristics that allow them to function in both endurance and power activities, but they do not specialize as efficiently for endurance as slow-twitch fibers. Hybrid fibers are not a distinct category recognized in standard muscle fiber classifications and may not have well-defined characteristics fitting the context of fatigue and endurance performance.