Sarah is a sprinter who specializes in quick and powerful bursts of speed followed by periods of rest.Priya is a marathon runner who specializes in long,steady runs.Compared to Sarah's muscles,how are Priya's most likely to differ?
A)Priya muscles will have more glycogen stored in her type 2X muscle fibers.
B)Priya's muscles will have more mitochondria in her type 1 and 2A muscle fibers.
C)Priya's muscles will have less myoglobin in her type 1 muscle fibers.
D)Priya's type 2X fibers will be larger in diameter.
E)Priya will have a greater proportion of type 2 muscle fibers and a lower proportion of type 1 fibers than Sarah.

Question

Quizplus · Accepted Answer

Marathon running requires the utilization of oxidative metabolism for energy production, so Priya's muscles would be expected to have more mitochondria in her type 1 and 2A muscle fibers to facilitate this process. Glycogen storage in type 2X fibers would be more important for sprinting (A), and myoglobin content typically increases in type 1 fibers, so Priya's type 1 fibers would likely have more myoglobin (C). While muscle fiber diameter can increase with training, there's no reason to assume that Priya's type 2X fibers would be larger in diameter (D). It's also not clear that Priya would necessarily have a greater proportion of type 2 fibers than Sarah (E).

Sarah Is a Sprinter Who Specializes in Quick and Powerful