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GR. 12 FITNESS
Health Unit 1
Mr. Mackay
MUSCULAR SYSTEM
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The human body is comprised of 324
muscles
Muscle makes up 30-35% (in women)
and 42-47% (in men) of body mass.
Three Types of Muscle
Skeletal muscle
Cardiac muscle
Smooth muscle
• Connects the various parts of the skeleton
through one or more connective tissue
tendons
• During muscle contraction, skeletal muscle
shortens and moves various parts of the
skeleton
• Activated through signals carried to the
muscles via nerves (voluntary control)
• Repeated activation of a skeletal muscle
can lead to fatigue
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STRUCTURE OF MUSCLE
d) myofibril
c) muscle fibre
b) muscle fibre bundle a) Muscle belly
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MUSCLE TEAMWORK
• Agonist (prime mover):
- Muscle or group of muscles producing a desired
effect.
• Antagonist:
- Muscle or group of muscles opposing the action.
• Synergist:
- Muscles surrounding the joint being moved.
• Fixators:
- Muscle or group of muscles that steady joints so
that the desired action can occur. (Stabilizers)
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MUSCLE TEAMWORK
Bending or straightening of elbow requires the coordinated
interplay of the biceps and triceps muscles
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MUSCLE PAIRING
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Bicep-Tricep
Pectorials-Rhomboids/Infraspinatus
Gluteus Maximus-Illiopsoas
Bicep Femoris-Rectus Femoris
Gastronemius-Anterior Tibialis
Anterior Deltoid-Poster Deltoid
Erector Spinai-Rectus Abdominus
Tensor Fasciae Latae-Gracilis
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FAST vs SLOW TWITCH
• SLOW: Suited for repeated contractions during
activities requiring a force output of < 20-25% of
max force output. ie: low power activities,
endurance events.
• FAST: Significantly greater force and speed
generating capability than slow twitch fibres.
• Well suited for activities involving high power.
• ie: sprinting, jumping, throwing
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MUSCULAR CONTRACTIONS
• Concentric: Muscle shortens under
tension.
• Eccentric: Muscle lengthens under
tension. (Negative)
• Isometric: Muscle remains the same
length under tension. (Flex & Hold)
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