Neuromuscular Function

Muscle Fiber Types

What are the three types of muscle fibers?

Briefly describe eachFiber type Slow Twitch (Type I)

Fast twitch A(Type IIA)

Fast twitch B(Type IIB)

Contraction time slow fast Very fast

Fatigue resistance high intermediate Low

Used for: Aerobic activity Long term anaerobic

Short term anaerobic

Capillary density High Intermediate Low

Mitochondria density

High High Low

Neuromuscular Function

Type I type IIA type IIB(Slow) (intermediate) (fast)

Recruitment of muscle fibers

Recruitment order of voluntary isometric & concentric contractions**

**No matter the type of exercise muscle always recruit this way

Neuromuscular Function

Recruitment of muscle fibers

Changing the recruitment pattern of muscle fibers

Eccentric muscle contractions (muscle lengthening) can change the recruitment pattern.

Fast twitch can be recruited first, then the slow twitch if the speed of the exercise is moderate to

fast.

Neuromuscular Function

Training specific muscle fiber types

How can we train our bodies to become better at certain activities?

What an athlete is born with is what he or she must live with.

You cannot increase the number of a specific fiber type but you can hypertrophy a specific type of

fiber through specific training , thus increasing the volume of that specific fiber type.

Neuromuscular Function

Muscle fiber composistion

How do we determine our muscle fiber type?

1. Muscle biopsy (best method)2. Testing an athletes muscle groups for

different muscle fiber properties. (chart from question 1)

Example: establish a 1RM of any exercise.lift 80% of 1RM as many times as possible.

7 or less reps most likely more than 50%FT fibers

12 or more reps most likely more than 50% ST fibers

Neuromuscular Function

Training specific muscle fiber types

Training recommendations:

Increase neuromuscular component of maximum strength:95% of 1RM, 1-3 rep range.

Increasing maximum strength by stimulating muscle hypertrophy:80% of 1RM, 5-8 rep range.

Increasing muscle size with moderate strength gains:% 1RM will vary, 6-12 rep range.