Transcript Muscles and Contractions board notes studnet copy

THE MUSCULAR SYSTEM
TYPES OF MUSCLE
--------------------– Are involuntary (no control) & found in
digestive tract, bladder & blood vessels.
– Move food through digestive tract
– They are slow sustained & rhythmic
– They fatigue more slowly than skeletal
muscles
• ---------------------– Found only in the Heart
– Involuntary (no control)
– Fibres are intertwined pushing blood into
arteries.
– Difficult to fatigue
– Nerve impulse messages relayed from cell to
cell causing rhythmic contractions & relaxation
• ---------------------------– Attaches to, and causes movement of the
skeleton
– ‘Striated muscle’ as it has a striped appearance
– Voluntary (have control)
– Also involved in reflex actions
– Messages sent from the brain to the muscle
concerned causes movement
• The ‘All or Nothing’ principle
– Nerve impulses will not stimulate muscle fibres until it
reaches a certain threshold level.
– Above the threshold muscles will _________________.
– Below the threshold muscles will _________________.
– Intensity of muscular contraction can vary depending
on:
• The _____________ of motor units stimulated
• The varying ______________ at which the impulses arrive at
the motor unit
Types of Contractions
• _______________________
– muscle length changes throughout the range of
movement (most common)
– Eg’s pushups, throwing, sit-ups, kicking
– 2 Types:
• Concentric - when muscle length shortens
during the contraction. eg Bicep in a Bicep
Curl
• Eccentric - when muscle lengthens while
force is being developed. Eg lowering body
in a sit-up.
– Isotonic contractions are effective in training as
you can easily adapt training activities to
resemble sporting movements.
– The disadvantage is that the greatest benefit is
at the weakest point in the muscle and
therefore the entire muscles range of motion is
not trained.
• ________________________
– When force is generated but there is no change in the
the length of the muscle
– Eg gripping a tennis racquet, pushing against a wall,
holding weights in stationary position.
– In isometric training you should train the muscle at
different joint angles to increase strength throughout
the entire range of motion.
– Isometric training can cause an increase in blood
pressure causing stress on the circulatory system.
• _____________________
– Develops maximal velocity throughout the entire range
of motion
– Involves the use of expensive machinery to train, such
as Cybex machines or a Hydra Gym
– Benefit of using these machines are that the amount of
force applied by the machine is the same at the force
applied by the muscle throughout the entire range of
motion.
– Considered the most effective way to train strength &
endurance.