Characteristics of Muscle Fibers

These flashcards cover key terms and definitions relating to muscle fiber types and their characteristics.

Slow-Oxidative Fibers (Type 1)

Muscle fibers that use oxidative phosphorylation for ATP production, characterized by high mitochondria, capillaries, myoglobin levels, slow contraction speed, and high fatigue resistance.

Fast-Oxidative-Glycolytic Fibers (Type 2A)

Muscle fibers that utilize both oxidative phosphorylation and glycolysis, featuring intermediate mitochondria, moderate myoglobin, fast contraction speed, and moderate fatigue resistance.

Fast-Glycolytic Fibers (Type 2X)

Muscle fibers that primarily rely on glycolysis for ATP production, characterized by few mitochondria, high glycolytic enzyme activity, very fast contraction speed, and low fatigue resistance.

Energy Source of Slow-Oxidative Fibers

Oxidative phosphorylation (aerobic respiration).

Energy Source of Fast-Oxidative-Glycolytic Fibers

Both oxidative phosphorylation and glycolysis.

Energy Source of Fast-Glycolytic Fibers

Primarily glycolysis (anaerobic respiration).

Fatigue Resistance of Slow-Oxidative Fibers

Very high; ideal for endurance activities like marathon running.

Fatigue Resistance of Fast-Oxidative-Glycolytic Fibers

Moderate; suitable for activities requiring both strength and endurance.

Fatigue Resistance of Fast-Glycolytic Fibers

Low; suited for short bursts of power or speed.

Structure of Slow-Oxidative Fibers

Characterized by small diameter, leading to fewer cross-bridges in parallel and less isometric tension.

Structure of Fast-Glycolytic Fibers

Characterized by larger diameter, allowing for more cross-bridges in parallel and higher force production.

Example of Slow-Oxidative Fibers

Postural muscles that help maintain standing without tiredness.

Example of Fast-Oxidative-Glycolytic Fibers

Muscles used for walking or moderate-intensity cycling.

Example of Fast-Glycolytic Fibers

Sprinter's leg muscles used for explosive movements.