TYPES OF SKELETAL MUSCLE:
Within our skeletal muscle we actually have 2 types of
muscle fibre called
fast slow
and
twitch fibres, related to the speed in which
they contract.
Both these fibre
types go back to
when we were
HUNTERS and
GATHERERS
Slow Fibres: Walk
long distances
Fast fibres: Chase
our prey when
needed
TYPES OF SKELETAL MUSCLE- TASK…
You will use all of the different types of muscle fibres during a game of football. However, some fibres are
particularly associated with different sports.
Type I fibres are typically employed in a warm up and at the beginning of exercise.
Type IIa fibres can be used for moderate intensity exercise. They are also often used for low intensity
aerobic activities when we are very fatigued and the Type I fibres are tired.
Type IIb fibres are used in explosive, powerful, fast movements. They tire very quickly.
In the space below give 5 sports that are primarily
associated with each muscle fibre type.
Then give at least 2 examples of a footballer using each
type of muscle fibre on match day.
TYPE 1- SLOW TWITCH FIBRES
RED in colour, as they have
a good blood supply
They are suited to endurance work
and are slow to fatigue- Due to
having a dense network of blood
vessels.
They also contain many
MITOCHONDRIA (Energy producing
organelles within cells), making them
more efficient at producing energy
using OXYGEN (O2).
TYPE 2A AND TYPE 2B- FAST TWITCH FIBRES
Fast twitch fibres
contract twice
as quickly as
slow twitch
fibres and
THICKER in size.
Their FASTER, HARDER contractions
make them suitable for producing
fast and powerful contractions. E.G:
Sprinting and Weightlifting
They have a poor blood supply, meaning
they are
whiter in appearance and
fatigue quicker due to
will
lack of OXYGEN (O2)
TYPE 2 (A)
Type 2 (b)
These fibres work when a person is
working close to their maximum
intensity. For example a 100m
runner would use these type of
fibres, or an Olympic lifter
performing a fast lift.
Work at slightly lower intensities, but
higher than slow twitch fibres are
capable of. For example a 400m runner
would utilise Type 2A fibres.
TRAINING EFFECTS FOR MUSCLE
FIBRES…
Type 1 and Type 2b fibres will always retain
Postural muscles
(muscles that keep us
standing upright) like the
their distinctive features… However Type
2a can take on characteristics of Type 1
and Type 2b depending on the training
done (they do not change their fibre type).
muscles in the legs,
back and abdominal
areas will be
predominantly SLOW
TWITCH. As they produce low
forces over a long period of
time.
The type of muscles found in the legs will determine
whether you are more suited to sprinting or
endurance running. Your athletic performances will b
a good indicator of which.
Bursztyn (1997): well trained middle- distance athletes
will have 80% slow twitch fibres and well trained
sprinters may have up to 75% fast twitch fibres
ANATOMY AND PHYSIOLOGY
UNDERSTANDING MUSCLE ACTION
Muscles are attached to bones by tendons.
The tendon at the non-moving (or
fixed) end is known as the origin.
The tendon at the moving end
is known as the insertion.
Muscles pull by contracting – they cannot push to produce
the opposite movement.
Muscles are arranged in antagonistic pairs.
As one muscle contracts (shortens) its partner relaxes (lengthens).
They swap actions to reverse the movement.
• To cause movement, muscles must
work across the joint.
– For example, the bicep works across the elbow joint
causing flexion of the elbow (bending)
• When the muscle contracts it pulls on
the bone, causing movement.
• The bones act like levers, and the
joints are the fulcrum.
• The strength of the contraction
depends on the amount of muscle
fibres brought into use.
– This is known as muscular fibre recruitment.
The biceps and triceps work
together as an antagonistic pair
to move the elbow joint.
To flex the elbow, the biceps
(the flexor) contracts and the
triceps (the extensor) relaxes.
To extend the elbow, the actions
are reversed so that the triceps
contracts and the biceps
relaxes.
The quadriceps and hamstrings in the legs are another
antagonistic pair. Can you answer the following questions?
Which joint do they move?
quadriceps
What types of movement are
produced?
hamstrings
Which is the flexor and which is the
extensor?
Identify the origin and insertion of
each muscle.
• Each muscle involved in the movement of a specific body part has a
role:
• Agonist/Prime Mover Muscle: this is the muscle that courses
the movement e.g the bicep causes the movement during a bicep curl
• Antagonist/Opposing Muscle: the opposing muscle must counter
the action of the primer mover muscle to allow the action to take place e.g. the
triceps must relax to allow for the biceps to contract during a bicep curl.
• Fixator Muscle: this muscle works to stabilise the joint at the origin of the
prime mover muscle e.g. the trapezius contracts to stabilise the origin of the
biceps during the bicep curl.
• Synergists: this muscle helps the prime mover
to produce the desired
movement by preventing any undesirable movements, during the upward
phase of the bicep curl the brachialis muscle is the synergist.
• There are 4 main types of contraction
1. Concentric Contraction:
Most common contraction, it takes place
when the ends of the muscle come
closer together and the muscle shortens
2. Eccentric Contraction:
The muscle ends move further away from
each other
3. Isometric Contractions:
A muscle exerts a force but does not
change in length E.G. during a tug of war
everyone is pulling the rope and your arm
muscles are contracting to do this but
your muscles are not shortening or
lengthening. A rugby league example
would be when both sides push in a scrum.
Video of an
eccentric,
concentric
and isometric
contraction
Eccentric- Involves
controlling the weight
on it’s way down
ConcentricContraction to
push weight away
from the body
• Where a muscle contracts, but
does not change in length
–The muscle is active in holding a
static position
• This is easy to train, but soon
leads to fatigue
function of the muscular
system and the different fibre types (Type
Describe the
1, Type 2a, Type 2b)
Explain the function of the muscular
system and the three different muscle
fibre types
Fibre types:
• Type 1
• Type 2a
• Type 2b
(Characteristics of both and
Sports associated with each)
Movement:
•
•
•
•
Antagonistic pairs (agonist, antagonist)
Fixator
Synergist
Types of contraction (isometric,
concentric, eccentric, isokinetic)
D1 builds on M1, and requires learners to
analyse the function of the muscular
system and the different muscle fibre
types.
Practical examples should be
provided where appropriate to support
the analysis