Matakuliah
Tahun
: L0252 – Computer Aided Learning = Technology
Psychology
: 2009/2010
KERJA OTOT
(Muscular Work)
Pertemuan 2
KERJA OTOT
(Muscular Work)
Bina Nusantara University
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STRUCTURE OF MUSCLE
At each end of the muscle (tendon) attached to
the bony skeleton.
A muscle contains between 100.000 and 1 Mio.
such fibres.
The fibres of long muscles are sometimes
bound together in bundles .
Each muscle consists of a large number of
muscle fibres, which can be between 5 mm –
140 mm long, according to the size of the
muscle. The diameter is about 0.1 mm.
Basic structure of skeletal muscle (adapted from Noakes, 1992)
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PHYSIOLOGICAL PRINCIPLES
The human body is able to move because it
has:
• System of muscles
(40% of total body weight)
The most important characteristic of a
muscle is its ability to shorten to about half
its normal resting length
= MUSCULAR CONTRACTION
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MUSCULAR CONTRACTION
Each muscle fibre contains proteins, including
actin & myosin which have
special importance for muscular contraction
The actin filaments curl around and slide along
the stationary myosin rods, thus shortening the
muscle
Actin
Myosin
Model
of University
Muscular contraction. The actin
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(Kroemer & Grandjean, 1997)
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MUSCULAR CONTRACTION
A muscle produces its greatest active
strength at the beginning of its contraction
R E L A K S
As the muscle shortens, its ability to
produce force declines.
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B E R K O N T R A K S I
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MUSCLES ACTIVITIES
1.
2.
BERKONTRAKSI
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RELAKS
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REGULATION OF MUSCULAR EFFORT
1.
The number of actively contracting muscle fibres
determines how strength is developed during the
period of contraction
3. The amount of muscle strength produced is
determined by the number of nervous impulses
The number of motor nerve cells in the brain that
have been excited
4.
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The speed of a muscular contraction depends
upon how quickly force is developed during a
given interval of time
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REGULATION OF MUSCULAR EFFORT
1.
2.
The number of actively
contracting muscle fibres
determines how strength is
developed during the period of
contraction
The amount of muscle strength
produced is determined by the
number of nervous impulses
3.
The speed of a muscular contraction depends upon
how quickly force is developed during a given
interval of time
The rapidity of a movement is governed by the
number of actively contracting muscle fibres
The number of motor nerve cells
in the brain that have been
excited
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SOURCE OF ENERGY
1. DIRECT
The energy released by chemical reaction
acts on the protein molecules (actin &
myosin), causing them to change position,
and so bring out contraction
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2. INDIRECT
The nutritive substances: glucose, fat and
protein  indirect energy sources for the
continuous replenishment of energy
reserves
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SOURCE OF ENERGY
1. GLUCOSE
The most important of the sugars circulating in the
blood, is the main energy supply in intensive
physical work.
It is immediately available and easily converted
2. COMPONENTS OF FAT & PROTEIN
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SOURCE OF ENERGY
2. COMPONENTS OF FAT & PROTEIN
1. GLUCOSE
For maintained physical work the
components of fat (fatty acids) and protein
(amino acids) are the dominant energy
supplies
The most important of the sugars
circulating in the blood, is the main
energy supply in intensive physical
work.
It is immediately available and easily
converted
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THE ROLE OF THE GLUCOSE, FAT & PROTEIN
1. GLUCOSE
The most important of the sugars
circulating in the blood, is the main
energy supply in intensive physical
work.
It is immediately available and easily
converted
2. COMPONENTS OF
FAT & PROTEIN
For maintained physical work the
components of fat (fatty acids) and protein
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(amino acids) are the dominant energy
supplies
1.
The glucose passes out of the bloodstream into the
cells, where ...
2.
... Where it is converted by various stages into
pyruvic acid.
3.
Further breakdown can take 2 directions, depending on
whether oxygen is available (aerobic glycolysis) or the
oxygen supply
is deficient (anaerobic glycolysis)
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THE ROLE OF THE OXYGEN
The role of
the Glucose, Fat & Protein
1.
Oxygen is PRESENT:
The pyruvic is further broken down by oxidation
(i.e. Under continuous oxygen consumption), the
end-products being water and carbon dioxide
1. The glucose passes out of the
bloodstream into the cells, where ...
2. ... Where it is converted by various
stages into pyruvic acid.
2.
3. Further breakdown can take
2 directions, depending on whether
oxygen is available (aerobic
glycolysis) or the oxygen supply is
deficient (anaerobic glycolysis)
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Oxygen is LACKING:
The normal breakdown of pyruvic acid cannot take
place. Instead, it is converted into lactic acid, a form
of metabolic waste product which plays a vital part
in symptoms of muscle fatigue and ‘muscular
hangover’
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Without O₂
With
O₂
LACTIC
ACID
Pyruvic Acid
Paying off
O₂ debt
Water
&
Carbon Dioxide
Chemical Reaction
Energy Flow
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Phosphate
Regeneration
GLUCOSE
Energy-RICH
MUSCULAR
CONTRACTION
LOW-Energy
Phosphate
Diagram of the metabolic processes which take place
during muscular work (Kroemer & Grandjean, 1997)
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DYNAMIC & STATIC FORM OF WORK
DYNAMIC effort is characterised
by an alternation of contraction and extension,
tension & relaxation;
 Muscle length changes, often rhythmically
STATIC effort is characterised
by a prolonged state of contraction of
the muscles
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STATIC
OR
DYNAMIC?
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STATIC OR
DYNAMIC?
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BLOOD SUPPLY
During a strong static effort the blood vessels are
compressed by the internal pressure of the muscle tissue, so
that the blood no longer flows through the muscle.
During dynamic effort, the muscle acts as a pump in the
blood system.
In fact:  The muscle may receive up to 20x more blood
than when it is resting
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EFFECTS OF STATIC WORK
1. The flow of blood is constricted
2. A higher energy consumption
3. Raised heart rate
4. Longer rest periods needed
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Force exerted as a percentage of maximum
Maximum duration of static muscular effort in relation to the force exerted. (Monod,
1967)
%
100
90
80
70
60
50
40
30
20
10
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1
2
3
4
5
6
7
8
9
10
min
Maximum duration of muscular contraction
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