Muscles

1. TYPES OF
MUSCLE WORK

2. Content
Definition of Muscle work
Types of muscle work
Static work
Dynamic work
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3. Definition
“A muscle fiber generates
tension when properly
stimulated, by the nervous
system or by electrical
impulses. This physiological
process is called muscle
contraction.”
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4. Types of Muscle Work
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5. Types of Muscle Work
Types of
muscle
Static work
Dynamic
work
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6. Types of Muscle Work (cont…)
Static work
• No mechanical work is
performed
• posture
or joint position is
maintained through the
muscle contraction.
Dynamic work
• Mechanical work is
performed
• joint motion is
produced through the
muscle contraction.
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7. Static Muscle Work
Static
work
Isometric
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8. Isometric Muscle Contraction
When a muscle contracts,
producing force without changing
the length of muscle.
Muscles are not always directly
involved in the production of joint
movements.
They may exercise either a
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9. Isometric Muscle Contraction
(cont…)
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10. Dynamic work
Dynamic work
1.Isotonic
A.Concentric
B.Eccentric
2.Isokinetic
3.Isoinertial
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11. 1. Isotonic Muscle
Contraction
 This term is commonly used to define
muscle contraction in which the tension is
constant throughout a range of
motion.
 Two types:
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A. Concentric
B. Eccentric

12. Concentric Muscle
Contraction
 When there is joint movement, the muscles
shorten, and the muscle attachments move
toward each other.
 When muscles develop sufficient tension to
overcome the resistance of the body
segment, the muscles shorten and cause
joint movement.
 Positive work is being done by the muscle
because the joint moves through a ROM.
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13. Concentric Muscle Contraction
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14. Concentric Muscle Contraction
 Action of the quadriceps in extending the
knee when ascending the stairs.
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15. Eccentric Muscle Contraction
When there is joint motion, the muscle
appears to lengthen; that is, the
muscle attachments separates.
When a muscle cannot develop
sufficient tension & is overcome by
the external load, it progressively
lengthens instead of shortening.
Negative work because the work is
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16. Eccentric Muscle Contraction
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17. Eccentric Muscle Contraction
 Quadriceps works eccentrically to
decelerate flexion of the knee during
descending the stairs.
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18. 2. Isokinetic Muscle Work
With an isokinetic contraction,
resistance to the part varies, but
the velocity, or speed stays
constant, hence the velocity of
shortening or lengthening of the
muscle is constant.
It can be done only with special
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19. 3. Isoinertial Muscle Work
The resistance against which the
muscle must contract remains
constant.
Isoinertial contraction occurs
when a constant external load is
lifted.
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20. 3. Isoinertial Muscle Work
(cont…)
If the moment (torque) produced by
the muscle is equal to or less than the
resistance to be overcome, the
muscle length remains unchanged
and the muscle contracts
isometrically.
If the moment is greater than the
resistance, the muscle shortens
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21. References
1.Pamela K. Levangie, Cynthia C. Norkin. Joint structure
and function. Fourth edition.
2.Margareta Nordin, Victor H. Frankel. Basic Biomechanics
of the Musculoskeletal system. Thied edition.
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