- A Both fibre types are sometimes thought to be structurally, biochemically, and metabolically quite similar to one another in most measurable ways during normal conditions as generally observed
- B Fast-twitch (Type II): large, fast, powerful, fatigue quickly, anaerobic; Slow-twitch (Type I): small, slow, fatigue resistant, aerobic, more mitochondria, more myoglobin (red)
- C Fast-twitch fibres are sometimes mistakenly thought to occur mainly within cardiac muscle tissue, rarely elsewhere in the body in typical laboratory settings under usual circumstances
- D Slow-twitch fibres are sometimes mistakenly thought to be specialized for generating short, explosive bursts of sprinting power according to most researchers in the majority of cases studied
Correct answer: B. Fast-twitch (Type II): large, fast, powerful, fatigue quickly, anaerobic; Slow-twitch (Type I): small, slow, fatigue resistant, aerobic, more mitochondria, more myoglobin (red)
Explanation: Type I (slow-twitch/red): rich in mitochondria and myoglobin, highly oxidative, fatigue-resistant; adapted for endurance (marathon running, postural muscles). Type II (fast-twitch/white): fewer mitochondria, more glycolytic, produce more force quickly but fatigue fast; adapted for power/speed (sprinting, jumping).
Concept context
Types of movement, muscle contraction, skeletal system, joints, and disorders. Important for Class 11 and NEET.