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Some muscles have more than one point of attachment at either
All skeletal muscles have origins and insertions. > Origins- found at
the end of the muscle where they remain fixed during movement. >
Insertions- found at the end of muscles where they move during
Muscular contractions- shorten muscles so a tendon is pulled at point
of insertion towards point of origin.
Antagonistic muscles- work in pairs. One muscle contracts (prime
mover) while the other relaxes (antagonist). e.g. the biceps and triceps.
In some cases there is a synergist; a muscle that assists the prime
mover by contracting simultaneously to provide movement.…read more

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2 types of fibres present in voluntary muscles:
Fast twitch- for short term power and strength activities. They contract very quickly and
powerfully. Burn up supply of oxygen quickly.
Slow Twitch- for long term endurance activities. Contract less violently and can sustain the
level of work for a longer period of time. Can replace their supply of oxygen while working.
distribution of fast-twitch and slow-twitch fibres is the same for all muscle groups. We
cannot change the proportions of each fibre in muscles. Although we can improve
performance through training, however we cannot increase our natural deposition to
be good at a particular type of activity. >>>Meaning, for example, although we may
improve our sprint time, we will never be as good as someone who naturally has a much
higher proportion of fast-twitch fibres in their muscles and trains just as hard as we do.
Better at Power/explosive events = generally higher proportion of fast-twitch fibres.
Better at endurance events = generally higher proportion of slow-twitch fibres.
Fast-twitch fibres burn up supply of oxygen quickly. They work anaerobically until more
oxygen arrives.
Slow-twitch fibres work at a much slower rate and are able to replace their oxygen supply
while working. They work aerobically throughout the exercise.
Anaerobic- working without oxygen.
Aerobic- working with oxygen.…read more

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Regular activity is essential to ensure muscular efficiency and health.
activity/training must be appropriate for intended purpose.
'off-season' exercise for athletes should be sufficient to maintain muscular efficiency.
Skeletal muscles become stronger the more they are used- Hypertrophy
Reduction of activity causes muscles to become weaker and smaller- Atrophy
Tendons attach muscle to bone
must be strong enough to work under heavy loads and resist the violent
muscular contractions involved in sporting skills i.e. throwing a javelin.
As a muscle contracts it is the tendon each end that take the strain: > Tendon of
origin resists the pull > Tendon of insertion exerts the pull on the bone it is
attached to.…read more

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Deltoids- front and rear of shoulder. Provide additional protection and stability to shoulder joint.
assist in raising arm. Significantly pronounced in performers who engage in sports involving
shoulders and arms.
Trapezius- Assists in raising and lowering head, shrugging shoulders, and adduction if scapular
when reaching forward with arms.
Pectorals- across front of chest. assist in raising the arms above the head in an outward movement
of upper arm. Participation in activities involving arms and shoulders produces highly defined
pectorals; i.e. swimming.
Biceps- Along front of upper arms. Function is to bend arm at elbow and work antagonistically with
the triceps. 'Athletic throwers', weightlifters and boxers have pronounced biceps due to their
prominent use in those activities.
Triceps- Rear of upper arm. Assist in straightening of arms at the elbow; i.e. in press-ups.
Antagonistic with biceps; elbow is bent by contraction of bicep and stretching of triceps, elbow is
straightened by stretching of bicep and contracting of triceps. Particularly apparent in throwing and
serving actions and during weight curls and press-ups.…read more

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Latissimus Dorsi- large sheet-like muscle along middle and lower spine. Reffered to as a
'pulling' muscle used in climbing or pulling on a rope. When relaxed it allows the raising of the arm
away from body, and assists in pulling the elbow towards the rear of the line of the upper body.
Much used by swimmers.
Abdominals- large group of muscles at front of abdomen. Assist in action of breathing and
supporting muscles of spine when bending and lifting. Help in sit-ups and leg raisers. Prevention
of back injuries by equating to the support the ribs give the upper body.
Gluteals- the buttocks. Assist in straightening the legs and trunk at the hips. Particularly
important in sprinting, jumping and pushing actions.
Quadriceps- made up of 4 muscles at the front of the thigh. 'Power muscles' significant in all
activities involving the straightening of the leg at the knee joint. Work antagonistically with the
Hamstrings- made of 3 muscles. Assist in bending the leg at the knee. Hamstring usually stringer
than quadriceps> resulting in hamstring injuries - particularly in soccer. Collectively the hamstring
and quadriceps must carry the weight of a performer's body in addition to fulfilling their roles in
performing activities.
Gastrocnemius- calf muscle, rear of the lower leg. Unites with the soleus muscle to form
the Achilles tendon. Assists in powerful; flexion at ankle joint. Works antagonistically with
the heel. When the heel strikes the ground the gastrocnemius relaxes; or when the
gastrocnemius contracts the heel relaxes allowing the ball of the foot and then the toes to
push against the ground.…read more


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