30. Adaptations to training- Skeletal muscle

Question 1

Discuss the prenatal development of muscle fibres?

Answer 1

Starts as a Dermomyotome -PAX3 and 7

Embryonnoic myoblasts/ fetal myoblasts/ satellite cells

Type 1 fibres (provide scaffold for) Type 2 fibres

Question 2

What can be said about muscle fibres from birth

Answer 2

They cannot change in number or proportion

Question 3

How does cross sectional area and fibre length of muscle fibres change after birth

Answer 3

They increase

Question 4

How do satellite cells contribute to ageing

Answer 4

They dont

Question 5

How do myonuclei increase?

Answer 5

In response to steroids or overload

Question 6

If you have large amounts of myonuclei what happens after de-training?

Answer 6

They can re-increase in number very quickly

Question 7

How are muscles repaired after trianing

What types of movement are more likely to injure muscles?

Answer 7

Myonuclei repeair muscles. Migrate towards damage and deliver mRNA for synthesis of proteins

Eccentric contractions are more likely to damage

Question 8

How are micronuclei signalled to repair muscle?

Answer 8

Trigger a signallign cascade including Cdc42 and phosphokinase C

Question 9

What are the role of satelite cells

Answer 9

Provide myonuclei for growth postnatally

Question 10

How does motor neuron size affect its ability to send an action potential?

Answer 10

Smaller motor neurons reach an action potential quicker in response to stimulation

Question 11

What is henneman’s size principle?

Answer 11

At lower effort only small motor neurons will be activated

At higher effort all motor neurons wil be activated

Question 12

What consequences does the hennemans principle have?

Answer 12

Fibres that are not recruited do not get adaptation inducing stimulus reuired for the shift in balance between synthesis and breakdown

Question 13

What can be said about how to generate increased force with exercise training?

Answer 13

High resistance and high effort allows for quicker increases in generation of force (90% of one rep max)

Question 14

What is meant by skinning muscle?

Answer 14

Denature proteins in the sarcolemma to allow various usbstances to pass into the muscle

Muscle fibres are fixed between two rods at optimumk length

Question 15

How do you calculate if fibres are kept at optimum length?

How do skinned muscle fibres contracted

Answer 15

Measure sarcomere length under microscope

When exposed to high calcium concentrations

Question 16

What is meant by max velocity of unloaded shortening?

Answer 16

Time taken for muscles to pick up slack when they are shortened when load is increased and then reduced to zero

Question 17

How do various fibres differ between maximum velocity of unloaded shortening?

Answer 17

Type IIX are quickest at reacting

Type II A are intermediate

Type I are slowest

Question 18

How do muscle fibres adapt to strenght trainin

Answer 18

All increase in peak force

All increase in CSA

None increase in Specific tension

All increase in power

None icrease in shortening velocity

Question 19

What do the results on strength training indicate

Answer 19

Increases cross sectional area leading to an increase in strength and therefore power due to larger myofibrils.

However it does not impact velocity

Question 20

With regards to plyometric training, how does the body adapt?

Answer 20

Plyometric exercise increases jump height

Doesnt particulalry change fibre type

Peak force increases in all

Cross sectional area increases in all

Velocity of unloaded shortening increases in all

Power increases in all

Question 21

What do the plyometric trainign results indicate

Answer 21

Increases power performance without changing fibre types

Question 22

What is meant by dual regulation theory

Answer 22

Actin may be able or unable to bind (activated by disinhibition of tropomyosin, caused by increase in calcium)

Myosin always has heads that are able to bind to actin but most of the actin heads are switched off

When there is resisistance at the end of the sarcomere the myosin filament is stretched releasing the heads and allowing maximal contraction

Question 23

Using dual regulation theory explain how plyometric training increases power output

Answer 23

Plyometric training allows for more myosin heads to be free when there is no resitance allowing more interaction with myosin

Question 24

What is the effect of endurance trainign on muscle fibres?

Answer 24

Increase in type I fibres, decrease in IIa fibres

Reduced cross sectional area of type I and IIa fibres

Peak force increases in type IIa fibres after tapering. No affect ot type I

Velocity of unloaded shortening increases in type I fibres

Peak power increases in Type I and Type IIa fibres