Skeletal Muscle Type

Fat distribution differences by Activity type may be the result of what?

-being born with that distribution and self-selecting into activities to which the musculature is optimized for. -Chronic training changing the distribution of fibers to match the demands placed on the system.

What are the characteristics of Type II muscle fibers?

-have larger alpha motor neurons. -faster nerve conduction velocity -more highly developed Sarcoplasmic Reticulum which outputs more calcium

What are most individuals muscles made up of?

50% slow-twitch Type I fibers 25% Type IIa fibers 25% Type IIx fibers *the percentage of each fiber type is variable among muscles, among individuals, and with exercise training.

Type IIx fibers

Are activated when the force demanded of a muscle is high. This is a type of fast fibers

What is the characteristic of slow fibers?

Higher aerobic endurance. Well suited for low-intensity endurance activities.

How is maximum velocity achieved?

It is always achieved at the lowest resistance

At any absolute force, where is velocity greatest in?

It is greatest in fast fiber muscles.

What does the Size Principle provide?

It provides optimal resistance to fatigue.

What is the Size Principle?

Motor units recruited in order of size of neuron. But we never recruit 100% of the available fibers.

What are Slow Fibers?

They are Type I fibers.

Type IIa fibers

They play a major role in high intensity exercise. This is a type of fast fibers.

Athletes in endurance events generally have an increased percentage of what fiber?

Type I

Athletes in speed and strength events generally have an increased percentage of what fiber?

Type II

What are Fast Fibers?

Type II fibers are better suited for anaerobic activity (maximal power).