Week 2 Muscular System

Question 1

Define Type I muscle fibres

Answer 1

Slow twitch fibres, associated with the aerobic energy system. Fatigue resistant.

Question 2

Define type IIa muscle fibres

Answer 2

Fast twitch fibres, associated with the anaerobic glycolysis energy system. Fire quicker than type I but create lactic acid, fatigue resistant

Question 3

Define type IIx muscle fibres

Answer 3

Fast twitch fibres associated with ATP-PCr energy system. Fastest speed fibres, fatigue/run out quickly

Question 4

What is the spatial recruitment: size principle

Answer 4

Size principle states that the order of recruiment is directly related to their motor neuron size, slow twitch fibres which have smaller motor neurons are recruited before fast twitch fibres

Question 5

What is the principle of orderly recruitment

Answer 5

States that motor units are activated in a fixed order, based on their ranking in the muscle

Question 6

What is the force-power relationship

Answer 6

At any given velocity of a movement the power generated is greater in muscle with a higher percent of fast twitch fibres

Question 7

What is a motor unit

Answer 7

A motor unit is made up of a motor neuron and the skeletal muscle fibers innervated by that motor neuron’s axonal terminals.

Question 8

What is the role of genetics regarding muscle fibre types

Answer 8

Genetics determines the type of motor neuron innervating individual muscle types, muscle fibres become specialized according to the type of motor neuron that stimulates them

Question 9

What is the optimal length of a muscle for maximal force?

Answer 9

2.25 micrometres

Question 10

What is the relationship between force and speed of a muscle?

Answer 10

The higher the speed means the higher the force

Question 11

What is the relationship between power and speed of a muscle?

Answer 11

The higher the speed means the higher the power until you overdo the speed then it declines

Question 12

What are factors influencing force production (6)

Answer 12

# of motor units activated
Type of motor units activated
Muscle size
Initial muscle length
Joint angle 
Speed of muscle action

Question 13

What do the receptors in muscles do

Answer 13

Provide sensory feedback to nervous system

 - Tension development by muscle
 - Account of muscle length

Question 14

Define Strength

Answer 14

Maximal force a muscle or muscle group can generate

Question 15

Define power

Answer 15

Production of strength and speed of a movement

Question 16

Define muscular endurance

Answer 16

Capacity to sustain repeated muscle actions

Question 17

Define fibre hypertrophy and fibre hyperplasia (muscle hypertrophy)

Answer 17

Hypertrophy is an increase in size of muscle fibres

Hyperplasia is an increase in number of muscle fibres

Question 18

Define difference between transient and chronic muscle hypertrophy

Answer 18

Transient is pumping of muscles during exercise due to fluid accumulation from the blood plasma
Chronic increase in muscle size after long term training

Question 19

Define how muscles actually become larger (fibre hypertrophy)

Answer 19

Number of myofibrils and actin and myosin filaments increase

Question 20

What are the two main processes that explain muscle soreness? (DOMs)

Answer 20

Microscopic tears in muscle fibres/connective tissue

Odema - accumulation of fluid inside muscle compartment

Question 21

List Armstrongs sequence of events (6)

Answer 21

1. Disruption of sacromeres
2. Membrane damage
3. Ca2+ leaks from SR
4. Protease activation
5. Inflammatory response
6. Edema and pain

Question 22

What is the repeated bout effect?

Answer 22

A bout of unfamilar exercises resulting in delayed onset muscle soreness. Following recovery, another bout of same exercise results in minimal injury

Question 23

What are the three theories for the repeated bout effect

Answer 23

Neural theory - recruitment of larger number of muscle fibres
Connective tissue theory - Increased connective tissue to protect muscle
Cellular theory - synthesis of protective proteins with muscle fibres

Question 24

Name the 4 neural adaptations of muscle strength

Answer 24

Synchronization and recruitment of additional motor units
Autogenic inhibition - sudden relaxation of muscle upon development of high tension
Coactivation of agonist and antagonist muscles
Rate coding - the firing frequency of motor units

Question 25

Define how early and long term gains of strength differ

Answer 25

Early gains in strength appear to be influenced more by neural factors
Long term strength increases are largely the result of muscle fibre hypertrophy

Question 26

How do delayed onset muscle soreness affect performance (5)

Answer 26

Decrease in force generating capacity in muscles
Physical disruption 
Failure in E-C coupling process
loss of contractile protein
Muscle glycogen synthesis impaired