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Your Muscles
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Types of Muscles
Cardiac Muscle
Found solely in the walls of the
heart
 It is similar to skeletal muscles in
that it is striated
 It is similar to smooth muscle in
that it’s contractions are not
under conscious control
 Highly specialized
 Highly resistant to fatigue

Smooth Muscle
Also known as unstriated muscles
due to the lack of the stripey
appearance
 Are involuntary because we are
not able to control them
 Found in the walls of hollow
organs such as the stomach,
bronchi and in the walls of blood
vessels

Skeletal Muscle
Attach to bone
 Main function is contracting to
facilitate movement of skeleton
 Also known as striated muscles
due to appearance
 Are voluntary because we control
them
 Have the ability to stretch or
contract and still return to their
original shape

Skeletal Muscle

There are 3 different fiber types of
skeletal muscle
 Type 1 – Slow Twitch
 Type 2A – Fast Twitch Oxydative
 Type 2B – Fast Twitch Glycolytic
ATP- Adenosine triphosphate - the
biochemical way to store & use energy.
For your muscles & every cell in your
body, it’s the source of energy that
keeps everything going.
Type 1 Fibers
Known as Slow Twitch Fibers
 Very resistant to fatigue
 Capable of producing repeated lowlevel contractions by producing large
amounts of ATP through an aerobic
metabolic cycle
 Mainly in postural muscles such as
neck & around spine
 Marathon runners have a high number
of this type of fiber, partly through
genetics, mainly through training

Type 2A Fibers
Known as Fast Twitch Oxydative Fibers
 Hybrid of type 1 & type 2
 Manufacture & split ATP at a fast rate
by utilizing both aerobic and
anaerobic metabolism
 Produce fast, strong muscle
contractions
 More prone to fatigue than type 1
 Resistance training can turn type 2b
fibers into type 2A due to enhanced
ability to utilize the oxidative cycle

Type 2B Fibers
Known as Fast Twitch Glycolytic Fibers
 Produce ATP at a slow rate by
anaerobic metabolism and break it
down very quickly
 Produce short, fast bursts of power
and rapid fatigue
 Found in large quantities in the
muscles of the arms
 More prone to fatigue than type 2A
 Can be turned into Type 2A by
resistance training
