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MUSCLES
TYPES OF MUSCLE
• There are 3 types of muscle:
- Involuntary (smooth)
– Cardiac
– Voluntary (skeletal/
striated/striped).
TYPES OF MUSCLE INVOLUNTARY
• Involuntary (smooth) muscle is found in
the internal organs of the body
e.g. the stomach and intestines.
• It is not under our ‘conscious’ control
but works automatically
e.g. the stomach contracts
automatically to digest food.
TYPES OF MUSCLE - CARDIAC
• Cardiac muscle is only found in the
heart.
• It is also involuntary and never stops
working until we die
e.g. the heart is always working to
pump blood around the body.
TYPES OF MUSCLE –
VOLUNTARY/SKELETAL
• Voluntary muscle is associated with
movement, and can be found all over the
body attached to the skeleton.
• It is under ‘conscious’ control
e.g. we use it when we
choose to move.
• This is the type of muscle that you
will learn about in this unit.
MAJOR MUSCLE GROUPS
ARMS AND
SHOULDERS
LEGS AND
BOTTOM
•Biceps (bends arm at
•Quadriceps
•Triceps (straightens
•Hamstring (bends
elbow)
arm at elbow)
•Deltoid (abducts
arm)
•Trapezius
shoulders)
(shrugs
(straightens leg at knee)
leg at knee)
•Gastrocnemius
(raises body onto toes)
•Gluteus Maximus
(straightens leg at hip)
THORAX
•Pectorals (brings
arms together in front
of body)
•Abdominals (bends
upper body at waist)
•Latissimus Dorsi
(pulls elbows towards
back)
HOW MUSCLES WORK
• Muscles work in pairs. When one muscle
contracts (the AGONIST or PRIME
MOVER), the other muscle relaxes (the
ANTAGONIST). This creates
movement of a bone at a joint.
• The INSERTION of a muscle is where
it attaches and resists pull.
• The ORIGIN of a muscle is where it
attaches and exerts pull.
HOW MUSCLES WORK
• A Bicep Curl in the Arm
• The bicep would be the prime
mover/agonist.
• The tricep would be the antagonist.
• The origin of the bicep would be at the
shoulder.
• The insertion of the bicep would be at
the elbow.
EXAMPLES OF
ANTAGONISTIC MUSCLES
• Biceps and triceps in the upper arm
Quadriceps and hamstring in the upper leg
TENDONS
• Tendons attach muscle to bone
• TENDON OF INSERTION – exerts pull
– In a bicep curl the tendon at the bottom of
the bicep that attaches to the elbow
• TENDON OF ORIGIN – resists pull
– In a bicep curl the tendon at the top of the
bicep that attaches to the shoulder
MUSCLE FIBRE TYPES
• Fast twitch fibres
–
–
–
–
Fast powerful contractions
Enough energy for 10seconds of exercise
Anaerobic energy systems used
E.g. weightlifting, sprinting, swimming 50m
MUSCLE FIBRE TYPE
• Slow twitch fibres
–
–
–
–
slower and less powerful contractions
utilise oxygen to provide energy for longer
aerobic energy systems used
e.g. cross country skiing, Tour de France
(cycling), marathon.
MUSCLE FIBRE TYPE
• Everybody has both types of fibre type
• It is possible to increase the efficiency
that the muscle fibres work at with
training
• Different activities use both fibre
types for different amounts of time
– e.g. marathon runners use slow twitch
fibres for most of the race but fast twitch
fibres for the sprint finish
MUSCLE FIBRE TYPE AND
SPORT
ACTIVITY
FOOTBALL
SLOW
TWITCH
Most of game
FAST TWITCH
Short sprints
Sprinting for the
ball in a rally
TENNIS
Most of match
BOXING
Duration of match Punching
EFFECTS OF TRAINING
• HYPERTROPHY – increase in muscle
size, strength and flexibility
• ATROPHY – decrease in muscle
size, strength and flexibility
(wasting of the muscle)
EFFECTS OF TRAINING
• MARATHON RUNNER
– slow twitch muscle fibres adapt to utilise energy
more efficiently and for longer periods of time
– delays the onset of muscle fatigue
– as little muscle bulk as possible
• SPRINTER
– more muscle fast twitch fibres are generated
(muscle bulk) to give more power output
– muscles are able to maximise stored energy to give
greater bursts of all-out activity