Question

part 3: muscle fibers
muscles have three main types of fibers:

• slow - twitch (type i): endurance, uses oxygen, long - lasting
• fast - twitch oxidative (type iia): moderate power, lasts 60 - 90 sec.
• fast - twitch glycolytic (type iib): short bursts, very powerful, fatigues quickly

1. which muscle fiber is used for a marathon?
2. which muscle fiber is used for sprinting?
3. which fiber type lasts about 8 seconds?
4. what type of athlete would use more slow - twitch fibers?
5. what energy source do fast - twitch glycolytic fibers rely on?
6. which type of fiber do you think is most common in weightlifters? why?

Explanation:

1. Marathons require endurance, so slow - twitch (Type I) fibers are used as they are long - lasting and use oxygen for endurance activities.
2. Sprinting requires short bursts of high power. Fast - twitch glycolytic (Type IIb) fibers are very powerful for short bursts, so they are used for sprinting.
3. Fast - twitch glycolytic (Type IIb) fibers are designed for short, powerful bursts and fatigue quickly, lasting about 8 seconds or short periods like this.
4. Athletes in endurance sports like long - distance running, cycling, or cross - country skiing use more slow - twitch fibers due to the need for sustained energy over long periods.
5. Fast - twitch glycolytic fibers rely on glycolysis (breakdown of glucose without oxygen) for energy, which provides quick energy for short, intense bursts.
6. Weightlifters need short, powerful bursts of energy for lifting heavy weights. Fast - twitch glycolytic (Type IIb) fibers are most common in weightlifters as they provide the high power needed for quick, intense muscle contractions during weightlifting.

Answer:

1. Slow - Twitch (Type I)
2. Fast - Twitch Glycolytic (Type IIb)
3. Fast - Twitch Glycolytic (Type IIb)
4. Endurance athletes (e.g., long - distance runners, cyclists)
5. Glycolysis (breakdown of glucose without oxygen)
6. Fast - Twitch Glycolytic (Type IIb) because they provide high power for short, intense muscle contractions needed in weightlifting.