30. Adaptations to training- Skeletal muscle Flashcards
(24 cards)
Discuss the prenatal development of muscle fibres?
Starts as a Dermomyotome -PAX3 and 7
Embryonnoic myoblasts/ fetal myoblasts/ satellite cells
Type 1 fibres (provide scaffold for) Type 2 fibres
What can be said about muscle fibres from birth
They cannot change in number or proportion
How does cross sectional area and fibre length of muscle fibres change after birth
They increase
How do satellite cells contribute to ageing
They dont
How do myonuclei increase?
In response to steroids or overload
If you have large amounts of myonuclei what happens after de-training?
They can re-increase in number very quickly
How are muscles repaired after trianing
What types of movement are more likely to injure muscles?
Myonuclei repeair muscles. Migrate towards damage and deliver mRNA for synthesis of proteins
Eccentric contractions are more likely to damage
How are micronuclei signalled to repair muscle?
Trigger a signallign cascade including Cdc42 and phosphokinase C
What are the role of satelite cells
Provide myonuclei for growth postnatally
How does motor neuron size affect its ability to send an action potential?
Smaller motor neurons reach an action potential quicker in response to stimulation
What is henneman’s size principle?
At lower effort only small motor neurons will be activated
At higher effort all motor neurons wil be activated
What consequences does the hennemans principle have?
Fibres that are not recruited do not get adaptation inducing stimulus reuired for the shift in balance between synthesis and breakdown
What can be said about how to generate increased force with exercise training?
High resistance and high effort allows for quicker increases in generation of force (90% of one rep max)
What is meant by skinning muscle?
Denature proteins in the sarcolemma to allow various usbstances to pass into the muscle
Muscle fibres are fixed between two rods at optimumk length
How do you calculate if fibres are kept at optimum length?
How do skinned muscle fibres contracted
Measure sarcomere length under microscope
When exposed to high calcium concentrations
What is meant by max velocity of unloaded shortening?
Time taken for muscles to pick up slack when they are shortened when load is increased and then reduced to zero
How do various fibres differ between maximum velocity of unloaded shortening?
Type IIX are quickest at reacting
Type II A are intermediate
Type I are slowest
How do muscle fibres adapt to strenght trainin
All increase in peak force
All increase in CSA
None increase in Specific tension
All increase in power
None icrease in shortening velocity
What do the results on strength training indicate
Increases cross sectional area leading to an increase in strength and therefore power due to larger myofibrils.
However it does not impact velocity
With regards to plyometric training, how does the body adapt?
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
What do the plyometric trainign results indicate
Increases power performance without changing fibre types
What is meant by dual regulation theory
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
Using dual regulation theory explain how plyometric training increases power output
Plyometric training allows for more myosin heads to be free when there is no resitance allowing more interaction with myosin
What is the effect of endurance trainign on muscle fibres?
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
