Question

Extensor muscles of back have

• A. An aerobic oxidation
• B. Fast rate of contraction
• C. Larger diameter muscle fibers
• D. Abundant in myoglobin

Answer 1

Answer: (A), (D)

The correct options are
A An aerobic oxidation
D Abundant in myoglobin

Extensor muscles. Attached to the back of the spine, these muscles allow us to stand and lift objects. They include the large muscles in the lower back (erector spinae), which help hold up the spine, and gluteal muscles.

Extensor muscles are one of the examples for red muscles which contains abundant mitochondria and myoglobin.

Red muscle fibres contract and fatigue more slowly than white fibres and generate ATP by aerobic catabolism of glucose and fats, utilizing myoglobin-bound O2

Myoglobin is abundant and great numbers of mitochondria occur, characterized by slow, sustained (tonic) contraction.

So, the correct answer is 'An aerobic oxidation and Abundant in myoglobin'