Chapter 2- Part 5

Question 1

What does the motor unit consist of?

Answer 1

Motor neuron and muscle fibres it stimulates

Question 2

What is the relationship between muscle fibres and force?

Answer 2

The more muscle fibres stimulated, the greater the force produced

Question 3

How does the number of muscle fibres vary for movement?

Answer 3

One motor neuron may stimulate only 1-2 muscle fibres for precise movement, but over thousands of muscle fibres may be stimulated for gross movement

Question 4

What do nerves, muscles and bones do together?

Answer 4

They combine to form a kinetic chain and produce movements

Question 5

What is a synapse?

Answer 5

A structure which permits the transfer of chemical transmitters

Question 6

What does the all or nothing principle state?

Answer 6

When the electrical impulse reaches a certain threshold, all the fibres of that motor unit will contract simultaneously as forcefully as possible

Question 7

What happens if the threshold is not reached?

Answer 7

Until the threshold is reached, none of the fibres will contract

Question 8

How is the intensity of muscle contractions varied?

Answer 8

By chaining the number of motor units stimulated and varying the frequency at which the impulses arrive at the motor unit

Question 9

What is recruitment?

Answer 9

The number of active motor units stimulated by the brain

Question 10

What is preferential recruitment?

Answer 10

When the body recruits muscle fibres according to demand

Question 11

When are slow-twitch fibres preferentially recruited first?

Answer 11

For a lower intensity event

Question 12

When are fast-twitch fibres preferentially recruited first?

Answer 12

For a higher intensity event, as they are the quickest to respond

Question 13

What are the characteristic of slow-twitch fibres which benefit athletes who recruit them?

Answer 13

High capillary density, high mitochondrial density and high triglyceride stores, which allows large amounts of blood and oxygen to be supplied

Question 14

What are the characteristics of fast-twitch fibres which benefit athletes who recruit them?

Answer 14

High glycogen stores, high phosphocreatine stores and high levels of glycolytic enzymes

Question 15

What are the basic characteristics of slow-twitch fibres (TYPE 1)?

Answer 15

Red, aerobic fibres, contain low amounts of force and speed, slow contraction speeds, high fatigue resistance, ideal for aerobic events such as jogging

Question 16

What are the basic characteristics of fast-twitch A fibres (TYPE 2A)?

Answer 16

Red/white fibres, moderate, recruited mainly for speed and power but also endurance, anaerobic/aerobic, ideal for events such as swimming and cycling

Question 17

What are the basic characteristics of fast-twitch B fibres (TYPE 2B)?

Answer 17

Large, white anaerobic fibres, rapid response, recruited for speed and power only, very low fatigue resistance, ideal for 100m sprint

Question 18

What do open kinetic chain exercises involve and give an example?

Answer 18

Usually not weight bearing, allow your limb to move freely with resistance applied at the end
Eg: Leg curls, Tricep Extension

Question 19

What do closed kinetic chain exercises involve and give an example?

Answer 19

Weight bearing exercises, involving the movement of multiple joints
Eg: Squats, Push-Ups, Calf Raises

Question 20

What is the difference in fibre recruitment for a 200m sprint compared to a sub maximal warm-down?

Answer 20

Fast twitch fibres are recruited during the 200m sprint, whereas slow twitch fibres are recruited during the warm down