What are the three types of muscle fibers? Neuromuscular Function Muscle Fiber Types What are the three types of muscle fibers? Briefly describe each Fiber 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 Mitochondria density

Neuromuscular Function Recruitment of muscle fibers Recruitment order of voluntary isometric & concentric contractions** Type I type IIA type IIB (Slow) (intermediate) (fast) **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? Muscle biopsy (best method) 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.