Download Worksheet Fibre types in action

Section A Chapter 1
Worksheet Fibre types in action – Teacher’s copy
(see student textbook, pages 17–20)
The diagram below shows a picture of a trampolinist during a routine.
1 Name the type of joint and identify the bones that articulate at the hip joint.
Type of joint: ball-and-socket
Articulating bones: pelvis and femur
2 During the routine the trampolinist performs a tuck jump. State the movement pattern
that occurs at the hip and the muscles responsible during this skill
Movement pattern: flexion
Muscles responsible: iliopsoas (hip flexors)
3 The muscles of a trampolinist will contain a high percentage of fast-twitch muscle
fibres. Using your knowledge of the structure and function of fast-twitch muscle fibres,
explain why this is so:
A trampolining routine is very explosive and only lasts a minute or so. Muscle fibres
responsible for explosive activities are fast-twitch fibres. In this instance, I think that the
trampolinist will have a high proportion of Fast-Oxidative Glycolytic (FOG or Type 2a)
fibres. The functional characteristics of which are that they have a high speed and force of
contraction as well as having a high anaerobic capacity, yet are able to withstand fatigue for
a short while. It is due to the structure of the muscle fibres that these functions exist. The
thick structure of the muscle fibre means that it contains high levels of ATP, PC and
glycogen, which allow lots of energy to be produced quickly and have moderate levels of
mitochondria and myoglobin, which help the FOG fibres to withstand fatigue.
4 State each of Newton’s three Laws of Motion and apply each to the trampolining
routine.
Newton’s First Law of Motion is the Law of Inertia. This states that ‘a body at rest or
moving in a straight line with constant velocity will continue to do so unless acted upon by
an external force’. The trampolinist will therefore remain stationary on the bed until his
muscles contract producing a force to overcome his inertia.
Newton’s Second Law of Motion is the Law of Acceleration and this states that ‘the rate of
change of momentum of a body is proportional to the force causing it and takes place in the
direction in which the force acts’. The greater the (reaction) force (of the bed), the greater
OCR PE for AS
© Hodder Education 2008
Dynamic Learning Network Edition CD-ROM
Section A Chapter 1
Worksheet Fibre types in action – Teacher’s copy
the acceleration of the trampolinist. As the reaction force is upwards the trampolinist will
accelerate in an upwards direction.
Newton’s Third Law of Motion states that ‘for every action there is an equal and opposite
reaction’. With reference to the trampolinist, this means that as the trampolinist lands on the
bed he produces a downwards ‘action’ force; in response, the trampoline bed produces an
equal and opposite force back onto the trampolinist, propelling the trampolinist into the air.
5 Using examples from the routine, state the different types of motion used when
trampolining. Explain how these types of motion are initiated.
There are three different types of motion:
• Linear motion: this is movement of a body or object that takes place in a straight line.
For example, when moving directly upwards or downwards on the trampoline in a straight
line
• Angular motion: this is when all parts of a body or object move in a circle or part circle
about a fixed axis of rotation. For example, when performing a tucked-back somersault
• General motion: a combination of angular and linear motion. For example, when
performing a tuck jump, the body is moving in a linear fashion upwards, but angular
motion occurs at the hip to cause flexion.
6 Study the information given in the table below.
Using the information in the table and reference to a range of sporting activities,
suggest how the structure of each fibre type suits its particular function.
The structure of Slow-Twitch fibres are suited to their function because they contain high
levels of mitochondria, myoglobin and triglycerides, which all help to produce energy
aerobically and offer great resistance to fatigue. They also have a high capillary density,
enabling greater amounts of oxygen to reach the muscle and allow waste products such as
lactic acid to be removed more quickly. A marathon runner or triathlete will undoubtedly
possess a very high proportion of Slow-Twitch muscle fibres.
The structure of Fast-Twitch Glycolytic fibres are suited to their function because they
contain high levels PC, ATP and Glycogen stores and low levels of mitochondria,
myoglobin and triglyceride stores. This means that they are used for very explosive
activities that are anaerobic in nature, such as shot putt or a 100 m sprint. These fibres are
very thick and therefore have a very high speed and force of contraction but fatigue really
quickly.
The structure of Fast Oxidative Glycolytic fibres are suited to their function because the
thick structure of the muscle fibre means that it contains high levels of ATP, PC and
glycogen, which allows lots of energy to be produced quickly and to moderate levels of
mitochondria and myoglobin, which help the FOG fibres to withstand fatigue. They have
greater anaerobic capacity but have some aerobic capacity so they will be useful in athletic
events such as the 1500 m or swimming a competitive 100 or 200 m race.
L
OCR PE for AS
© Hodder Education 2008
Dynamic Learning Network Edition CD-ROM
Section A Chapter 1
Worksheet Fibre types in action – Teacher’s copy
Slow-Twitch
(Type 1)
Fast-Oxidative
Glycolytic (FOG)
(Type 2a)
Fast-Twitch
Glycolytic (FTG)
(Type 2b)
Speed of contraction (ms)
Slow (110)
Fast (50)
Fast (50)
Force of contraction
Low
High
Highest
Resistance to fatigue
Very high
Moderate
Low
Aerobic capacity
Very high
Moderate
Low
Anaerobic capacity
Low
High
High
Fibre size
Small
Large
Large
Mitochondrial density
High
Moderate
Low
Capillary density
High
Moderate
Low
Myoglobin content
High
Moderate
Low
PC store
Low
High
High
Glycogen store
Low
High
High
Triglyceride store
High
Moderate
Low
Motor neuron size
Small
Large
Large
Activity suited
Marathon
1500 m
Shot putt
Functional Characteristic
Structural Characteristic
OCR PE for AS
© Hodder Education 2008
Dynamic Learning Network Edition CD-ROM