Types of Skeletal Muscle Fibers

Method of ATP manufacture

One of the two characteristics skeletal muscle fibers are characterized by: 1

How quickly they contract

One of the two characteristics skeletal muscle fibers are characterized by: 2

Oxidative fibers

Produce ATP aerobically inside the mitochondria

Glycolytic fibers

Produce ATP anaerobically, without oxygen, by glycolosis outside of the mitochondria

Slow oxidative, fast glycolytic, and fast oxidative fibers

The three classes of muscle fibers

A mixture of muscle fibers

Are included in each muscle

Slow oxidative fibers

Small fibers that need oxygen, contract slowly, and are resistant to fatigue. They are good for standing.

Aerobic metabolic reactions

Method of obtaining energy in slow oxidative skeletal muscle fibers

Myoglobin

Contained in slow oxidative skeletal muscle fibers and gives them their red color.

Large amounts of mitochondria and capillaries

Contents of slow oxidative skeletal muscle fibers.

Aerobic

With oxygen

Anaerobic

Without oxygen

Fast glycolytic fibers

Pale fibers that are twice the diameter of slow oxidative fibers, do not need oxygen, contract rapidly, and tire quickly. They are good for short sprints

Little myoglobin and few mitochondria,

Contents of fast glycolytic skeletal muscle fibers

Generate more power

Fast glycolytic skeletal muscle fibers, because they have more myofibrils

Fast oxidative fibers

Fibers that have an intermediate diameter, need oxygen, contract quickly like fast glycolytic fibers, and are somewhat fatigue resistant. They are good for long distance runs.

More powerful

Fast oxidative fibers compared to slow oxidative fibers

Lots of myoglobin and capillaries

Contents of fast oxidative skeletal muscle fibers