Download Function of the Muscular system

Muscular system: Fibre types and
contractions
BTEC L3 Sport
Kevin Browne
Aims of the lesson
• Outline the types and difference of fibre types
• To identify the main function of the muscular
system
• Outline and describe the roles of muscle in
order to provide it main function
Task
• Individually write your own description of
what a slow twitch fibre
• Key words may include
• Contraction
• Endurance
• Energy production
• Force production
Slow twitch fibre
• These will be red in colour as they have good
blood supply. They will have a dense network
of blood vessels making them suited to
endurance work and they are slow to fatigue
• They contain many mitochondria to make
them more efficient at producing energy using
oxygen
• Individually write your own description of
what a fast twitch fibre
• Use the same keywords as before
• FTF will contract as twice as quick as STF and
are thicker in size. They have a poor blood
supply and are whiter in appearance and will
fatigue quickly.
• They are harder faster contractions making
them suitable for sprinters
What's the difference between type 2a
and 2b
• The type that is used depends upon the
chosen activity. Type 2b fibres work when a
person is very close to their maximum
intensity.
• Type 2a work at slightly lower intensities but
still much higher than slow twitch fibres
• Can you give me an example of this?
Characteristics
Speed of contractions
Force of contractions
Size
Mitochondrial density
Myoglobin density
Fatigability
Aerobic capacity
Capillary density
Anaerobic capacity
Motor neuron size
Slow twitch (T1)
Fast oxidative
glycolytic F.O.G (T2A)
Fast twitch glycolytic.
F.T.G. T2B
Characteristics
Slow twitch (T1)
Fast oxidative
Fast twitch glycolytic.
glycolytic F.O.G (T2A) F.T.G. T2B
Speed of contractions Slow (110)
(ms)
Fast (50)
Fast (50)
Force of contractions
low
High
High
Size
Smaller
Large
Large
Mitochondrial density High
Lower
Low
Myoglobin density
High
Lower
Low
Fatigability
Fatigue resistant
Less resistant
Easily fatigued
Aerobic capacity
High
Medium
Low
Capillary density
High
High
Low
Anaerobic capacity
low
Medium
High
Motor neuron size
Small
Large
Large
Contracting muscles
• What is the main function of muscles?
• Simply movement
• When a muscle contracts it pulls on the
tendon which in turn pulls the bone and
makes the bone
• When muscles contract they work as a group
in that the muscles contracting is dependent
on the other muscles doing their job
• A muscle can play one of the four roles
4 roles
• Agonist (prime mover): the muscle contracts
to produce the desired movement
• Antagonist : this muscle relaxes to allow the
agonist to contract
• Synergist : this muscle assists the agonist in
producing the desired movement
• Fixator :these muscles will fix joints and the
body in position to enable the desired
movement to occur.
• During the upward phase of the bicep curl the
biceps are the agonist and are contracting
concentrically. During the downward phase the
biceps are still the agonist but this time they are
contracting eccentrically. They are in effect acting
as a brake, resisting gravity to control the
downward phase of the exercise.
• This is sometimes a difficult concept to
understand and you may find it useful to try the
exercises and feel how the muscles are working.
Movement
Agonist
Antagonist
Fixator
Synergist
Elbow Flexion
Biceps
Triceps
Deltoids
Brachialis
Concentric
Eccentric
Muscle length
Shortens under tension
Lengthens under tension
Effect on movement
Causes movement
Controls movement
Example 1
Bicep curl upward phase
Bicep curl lowering phase
Example 2
Leg extension
Upward phase of a lateral
pull down the biceps and
latissimus dorsi are
controlling the movement
Summary
• Questions
• You tell me!
• True or false