BTEC Sport
Muscles and Muscle Action 2
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Learning objectives
Learning objectives
What we will learn in this presentation:
The role of antagonistic muscle pairings and their
importance to movement
The differences between static, dynamic and explosive
strength and the different types of contraction
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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 groups/teams or Antagonistic Pairs.
As one muscle - Prime Mover or Agonist - contracts
(shortens) its partner - Antagonist relaxes (lengthens).
They swap actions to reverse the movement.
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Upper arm muscles
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.
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Quadriceps / Hamstring muscle action
The quadriceps and hamstrings in the legs are another
antagonistic pair. Can you answer the following questions?
Which joint do they move?
What types of movement
are produced?
Which is the flexor and
which is the extensor?
quadriceps
hamstrings
Identify the origin and
insertion of each muscle.
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Properties of Skeletal Muscle
Skeletal Muscle possesses 3 essential properties:
1. Extensibility: the ability of muscle tissue to
lengthen when contracting
2. Elasticity: the ability of muscle tissue to return to
its normal resting length once its has been
stretched
3. Contractility: this refers to the capacity of a
muscle to contract or shorten forcibly when
stimulated by nerves and hormones (excitability)
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Muscle Contractions
There are 3 main types of muscle contraction:
Concentric
Eccentric
Isometic
Happens when
the muscle
shortens as it
contracts.
Is the opposite of
Concentric. The
muscle lengthens
as it gains tension
Eg: Flexing the bicep
muscle
Eg: Lowering of a
weight after having
performed a bicep curl
Happens when
there is tension on
the muscle but no
movement is made,
causing the length
of the muscle to
remain the same.
Eg: As in the arm
muscles in a handstand
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Isometric contractions
Isometric contractions do not create movement – the
muscle neither shortens nor lengthens. Isometric
contractions produce static strength.
To support a weight
in a stationary
position.
To hold the body in a
particular position
(e.g., in gymnastics).
To stabilize part of
the body so
movement can occur
elsewhere.
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Isometric contractions
occur in a rugby scrum
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This type of contraction occurs in several situations:
Muscle quiz
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Exam-style questions
1. This picture shows part of the muscular system.
a) Name muscles a–e.
b
Janine exercises her deltoids by
lifting heavy weights. She raises
her arms out to the sides until her
d
hands are level with her shoulders.
b) What type of movement is
occurring at the shoulder?
a
c
e
c) What type of muscle contraction is involved?
Janine changes her exercise to holding the weights out
to the sides at shoulder level for 10 seconds at a time.
d) What type of strength will this improve?
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Exam-style questions
2. Explain what is meant by an antagonistic pair and give
one example.
3. Complete the ‘Muscle Contraction’ Worksheet that
Mr.Brady has handed out.
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