Question

Select the incorrect match from the following:

• A. Red muscle fibres - High myoglobin level
• B. White muscle fibres - Fast twitching
• C. Red muscle fibres - Slow twitching
• D. White muscle fibres - High myoglobin level

Answer 1

The correct option is D White muscle fibres - High myoglobin level

A muscle is made up of a number of bundles of muscle fibres; such bundles are called fascicles. These muscle fibres are multinucleated (syncytium) and consist of parallel filaments called myofibrils. Muscle fibres are further classified into two types:
i) Red fibres: These are slow twitching (contract slowly) fibres and have high levels of myoglobin and many mitochondria. They derive their energy from aerobic respiration and are capable of sustained vigorous activity. In general, marathon runners have more red fibres.
ii) White fibers: These are fast twitching fibres and contain lower levels of myoglobin and fewer mitochondria. Because of their composition, they derive more of their energy anaerobically and fatigue more easily. Short distance runners usually have more white fibres.