1.4.2 The Motor Unit

Question 1

What are the three types of muscle fibers

Answer 1

Type 1
Type 11a
Type 11b

Question 2

What are type 1 muscle fibers

Answer 2

Slow oxidative muscle fibers

Question 3

What are type 11a muscle fibers

Answer 3

Fast oxidative glycolytic muscle fibers

Question 4

What are type 11b muscle fibers

Answer 4

Fast glycolytic muscle fibers

Question 5

What are the characteristics of type 1 muscle fibers

Answer 5

Slow twitch
High number of mitochondria
High levels of myoglobin
High levels of fat stores
Slow to fatigue
Low levels of force production

Question 6

What are the characteristics of type 11a muscle fibers

Answer 6

Fast speed of contraction
High force levels
High PC stores
Quick to fatigue
Large neurone size and fast motor neurone conduction

Question 7

What are the characteristics of type 11b muscle fibers

Answer 7

Very fast speeds of contraction
Very high force production
Very high PC stores
Very quick to fatigue

Question 8

What is the main sporting examples that use type 1 muscle fibers

Answer 8

Cross country,1500m,Marathon

Question 9

What are some sporting examples of the use of type 11a muscle fibers

Answer 9

400m,Speed endurance events

Question 10

What are some sporting examples of the use of type 11b muscle fibers

Answer 10

100m,high jump,shotput

Question 11

What is the recovery rate for type 1 muscle fibers

Answer 11

Recover quickly as no fibre damage,However recovery can be increased by the length of the exercise

Question 12

What is the recovery time for type 11b muscle fibers

Answer 12

Used during anaerobic exercise,Fatigue more quickly and use maximal effort that can cause muscle damage.Leading to DOMS

Question 13

How do our muscles exert different amounts of force or tension dependent on the activity

Answer 13

They’re generally affected by both the frequency and strength with which they’re stimulated by the motor neurone

Question 14

What is meant by the all or none rule

Answer 14

When an impulse is sent via a motor neurone and the impulse passes ‘the threshold’,all muscle fibers in the Motor unit will contract if the impulse isn’t high enough contraction will not occur

Question 15

What are the three distinct phases of a single muscle twitch

Answer 15

Latent period
Period of contraction
Relaxation period

Question 16

What is the ‘latent phase’ in a muscle twitch

Answer 16

The time before contraction where tension isn’t increased

Question 17

What is the ‘period of contraction’ in a single muscle twitch

Answer 17

The period where the muscle contracts allowing for the load to be lifted/the action to be performed

Question 18

What is the ‘relaxation period’ in a muscle twitch

Answer 18

The period after the period of contraction where the muscles return to their original size

Question 19

What is wave summation

Answer 19

Where there is a repeated nerve impulse with little time to relax so a smooth sustained contraction occurs,rather than twitches.If another stimulus is applied before the muscle fully relaxes more tension occurs

Question 20

What is a tetanic contraction

Answer 20

A sustained muscle contraction caused by a series of fast repeating stimuli,higher stimulus frequency-no relaxation

Question 21

What is spatial summation

Answer 21

When the strength of a contraction changes by altering the number and size of the muscle’s motor units e.g putting in golf will only use a few motor units in the traps/pecs,whereas passing a rugby ball forcefully will use all fibres attached to these muscles