Type 1 muscle fibers are slow-twitch and linked to which activities?

• A. Slow-twitch (10k run, light resistance work)
• B. Fast-twitch for sprint
• C. Fast-twitch for maximal strength
• D. Intermediate fibers for mid-distance

Answer: (A)

Slow-twitch muscle fibers (Type I) are built for endurance. They rely mainly on aerobic metabolism, have many mitochondria and capillaries, and carry high myoglobin, which lets them sustain contractions for long periods without fatiguing quickly. Because they generate less force per contraction but can work continually, they’re activated during prolonged, steady efforts or light resistance work that involves higher repetitions. That’s why activities like a 10k run or light resistance training fit well with these fibers. In contrast, fast-twitch fibers are used for short, explosive efforts such as sprints or maximal lifts, and intermediate fibers are involved in mid-distance work.