Question

In which of the following functions are white muscles used?

• A. Moving of eyeballs
• B. Fast and strenuous workout, for short duration.
• C. Fast flight as in sparrows
• D. For sustained work at a slow rate, for a long duration

Answer 1

Answer: (A), (B), (C)

Fast flight as in sparrows

White muscles depend on anaerobic metabolism for energy (glycolysis). Lactic acid accumulation occurs due to glycolysis. Mitochondria are less abundant, and they perform fast and strenuous work for a short period (fast work but soon fatigue sets in). This is why moving of eyeballs, a fast workout and the flight of a sparrow makes use of white muscles.

Whereas, red muscles are for endurance, and they depend on aerobic metabolism for energy (oxidative phosphorylation). Mitochondria and myoglobin are abundant in red muscles and there is no accumulation of lactic acid.