7. Slow-oxidative fibers and fast-glycolytic fibers are two types of cells that make up skeletal muscles - the type of muscle that allows you to move your body. Slow-oxidative fibers, which contain many mitochondria, contract slowly and tire out slowly, allowing for sustained postures or movements. Fast-glycolytic fibers, which contain very few mitochondria, contract rapidly to produce powerful, quick movements, but tire out rapidly as well. Most of the ATP produced in fast-glycolytic fibers comes from glycolysis.
(a) Suggest why these two types of skeletal muscle fibers have different amounts of mitochondria.
(b) It can be much faster to produce ATP by glycolysis than by oxidative phosphorylation.
How would it benefit a sprinter to have high numbers of fast-glycolytic fibers?
(c) It would benefit a sprinter to have high numbers of fast-glycolytic fibers because these fibers contract rapidly and produce powerful, quick movements. This allows sprinters to generate a burst of speed and accelerate quickly.
How would it benefit a long-distance runner to have high numbers of slow-oxidative fibers?
(d) It would benefit a long-distance runner to have high numbers of slow-oxidative fibers because these fibers contract slowly and tire out slowly. This allows long-distance runners to maintain a sustained pace for extended periods of time without getting fatigued easily.
