Kin 202 Muscle Fibers Exam 4

Structural Characteristics of Slow Twitch

Slow, low force, fatigue resistant

Structural Characteristics of Fast Twitch A

Fast, high force, most fatigue

Structural Characteristics of Fast Twitch B

Fast, high force, high fatigue

Metabolic Characteristics of Slow Twitch

Low PCr and glycogen stores, high fat stores, low anaerobic enzymes, and high aerobic enzymes

Metabolic Characteristics of Fast Twitch A

High PCr and glycogen stores, medium fat stores, high anaerobic enzymes, and low aerobic enzymes

Metabolic Characteristics of Fast Twitch B

High PCr and glycogen stores, low fat stores, high anaerobic enzymes, and low aerobic enzymes

Motor Neuron Characteristics of Slow Twitch

A2 neuron types, low conduction velocity, low recruitment threshold

Motor Neuron Characteristics of Fast Twitch

A1 neuron types, high conduction velocity, and high recruitment threshold

High intensity exercise

Recruit more fast twitch muscle fibers with a high recruitment threshold (Strength training athletes)

Low intensity exercise

Recruit more slow twitch muscle fibers with a low recruitment threshold (Endurance athletes)

Size principal of Fiber Recruitment

Muscle fibers are recruited from smallest to largest

Type 1/small motor units recruited first