BINA NUSANTARA
Pertemuan 4
BINA NUSANTARA
Isometric Force
(% of Maximum)
MAXIMUM MUSCLE STRENGTH
(Prinsip Motion Economy 1)
100
50
50
Complete
Contraction
100
150
Complete
Extension
Length of Contractile Element
(% of Resting Length)
Relaxed Posture assumed by People in Weightless Conditions
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Hasil Penelitian HUNSICKER
Gerakan Menarik dan mendorong merupakan Gerakan Terkuat
Kekuatan tersebut tergantung pada Sudut
Gerak Menarik mencapai kekuatan maksimum pada sudut 150
Gerak Mendorong mencapai kekuatan Maksimum pada sudut 180
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Hasil Penelitian
Provins dan Salter (1955) dan Singh dan Kaporvich (1966)
Posisi forearm terhadap Sumbu Siku
Sudut siku 900 menberikan gaya momenmaksimum pada FLEKSI DAN EKSTENSION
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TENSION
Streched : Terentang. Minimal Overlap / ikatan
antara Actin dan Myosin. Berkurangnya
Gaya Otot Hingga 0.
Istirahat Posisi Optimum untuk Tegangan,
Posisi Netral, Sekitar Midpoint pada Normal
Range dari Gerakan
Contracted : Actin dan Myosin membentuk Cross
Bridge. Cross Bridge ini Menghasilkan
Tegangan Otot .
Complete Contracted State :
Berkurangnya Gaya Otot, karena
gangguan pada Actin, sehingga Ikatan
optimum terganggu.
Tension yang dapat dihasilkan Otot Tergantung pada :
1. Luas penampang Otot
2. Panjang Otot : Panjang Otot pd Complete Contraction (50% dari Panjang
Otot Sewaktu Istirahat) sd Complete Extension (SD 180%
Panjang Otot sewaktu Istirahat )
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HUMAN STRENGTH
DYNAMIC STRENGTH :
Menghasilkan Gaya Otot yg
Menggerakan Bagian Tubuh
STATIC STRENGTH :
Tertahannya Gerakan
Bagian Tubuh
PSYCHOPHYSICAL
STRENGTH :
Strength Demands
are Required for an
Extended Period of
Time
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DYNAMIC STRENGTH
<
STATIC STRENGTH
More Efficient Bonding
In the Slower Sliding
Muscle Filaments
GAYA ISOTONIS /
ISOTONIC CONTRACTION :
Memanjang dan Memendeknya Otot
Dengan Menghasilkan Kerja
Konsentris : Memendeknya Otot sambil
Tetap Menahan suatu
Tegangan (Kerja Positif)
Eksentris : Memanjang Otot sambil
Tetap Menahan suatu
Tegangan (Kerja Negatif)
GAYA ISOMETRIS/
ISOMETRIC CONTRACTION :
Gaya Otot tanpa Menghasilkan Kerja
Diukur oleh : CONSTANT VELOCITY (ISOKINETIC) DYNAMOMETER
MAXIMUM STRENGTH With SLOW MOVEMENT
(Prinsip Motion Economy 2)
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The faster the molecular bonds are formed, broken and reformed,
the Less Effective is the bonding and the less muscular force
is produced
Force
(% maximum)
Force – Velocity Relationship
Heavy Manual Work
100
Maximum Muscle Force dihasilkan dari :
No Externally Measurable Shortening
(Velocity 0 or Static Contraction)
50
Minimum Muscle Force dihasilkan dari :
0
Maximum Velocity of Muscle Shortening
0
50
100
Velocity
(% of Maximum No Load-Velocity)
Force is only sufficient to move the mass
of the body
USE
MOMENTUM TO ASSIST WORKERS WHEREEVER POSSIBLE :
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Minimize It if It Counteracted by Muscular Effort
(Prinsip Motion Economy 3)
Faster Movements
Higher Momentum + Higher Impact Forces
Downward motions are More Effective than Upward Motions
USE LARGE MUSCLES FOR TASKS REQURING STRENGTH
(Prinsip Motion Economy 5)
Muscle Strength = f ( Size of Muscle)
Size of Muscle = Cross Sectional Area = f ( Posture)
Ex : Heavy Load Lifting : Leg and Trunk Muscles
DESIGN TASKS TO OPTIMIZE HUMAN STRENGTH CAPABILITY
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(Prinsip Motion Economy 4)
Human Strength Capability
depends on :
ARM LIFTING STRENGTH TEST
1. The Type of Strength
2. The Muscle or Joints Motion
being Utilized
3. Posture
4. Individual Factors :
• Gender, (The Largest Effect)
• Age,’
• Handedness
• Fitmess/Training
LEG LIFTING STRENGTH TEST
STATIC STRENGTH POSITIONS
Range of Strength in the Normal,
Healthy Adult population =
The Strongest = (5 to 8) x The Weakest
TORSO LIFTING STRENGTH TEST
ENERGY SOURCES, STRENGTH AND FATIGUE
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AEROBIC
ATP+02
ANAEROBIC
ADP + ENERGI+CO2+H20
ATP
ADP + ENERGI+LACTIC ACID
Energy for a very Small Period of Time
HUMAN STRENGTH
Arterioles + Capillaries : Compressed
Blood Flow and O2
DYNAMIC STRENGTH :
Menghasilkan Gaya Otot yg
Menggerakan Bagian Tubuh
Fatigue
STATIC STRENGTH :
Tertahannya Gerakan Bagian Tubuh
STAY BELOW 15 % OF MAXIMUM VOLUNTARY FORCE
(Prinsip Motion Economy 6)
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100 % Maximal Contraction, Endurance Time = 6 Seconds
15 % Maximal Contraction, Endurance Time = Indefinite !
5 – 10% (Jonsson,1978)
The Amount of Rest Needed to Recover from Static Hold =
Relaxation Allowances = f ( Force Exerted, Holding Time)
Endurance
Time (min)
10
Indefinite time
Endurance Time = T
T = 1.2 / (f – 0.15)0.618 – 1.21
5
6 sec
15%
0
20 40 60 80 100
f = Required Force, fraction of Maximum
Isometric Strength
Exertion Level ( % Max Muscle Forces)
USE SHORT, FREQUENT, INTERMITTENT WORK-REST CYCLES
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% of Maximum Strength
(Prinsip Motion Economy 7)
90
85
80
75
70
65
60
0 5 10 15 20 25 30
Contraction/min
Repeated Static Contraction ( bawa barang dgn siku flexi), or dynamic work
(mencangkul),
Short time and Frequent cycle
A Much Higher Percentage of Maximum Strength can be
Maintained if the Strength is Exerted as a Series of Repetitive
Contractions rather than One Sustained Static Contraction.
Complete muscle fatigue
several hour recovery
DESIGN TASKS SO THAT MOST WORKERS CAN DO THEM
(Prinsip Motion Economy 8)
Muscle Fiber
Strength
100
Muscle Mass
80
Average Female Strength =
40
60
Male
(35% to 85%) x Average Male Strength
Or 66 % x Average Male Strength
20
Female
0
% Variation in Muscle Strength
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0 10 20 30 40 50 60 70 Age Years
CHANGES IN MAXIMAL ISOMETRIC STRENGTH WITH AGE
Greatest for Upper Extremity Strength and Smallest for Lower Extremity Strength =
= f ( body size or Total Muscle Mass)
By a Strength Training Program
Increase Strength 30% - 100%,
in the First Several Weeks
Force (% maximum)
0 10 20 30 40 50 60 70 80 90 100
USE LOW FORCE FOR PRECISE MOVEMENTS OR
FINE MOTOR CONTROL
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(Prinsip Motion Economy 9)
Higher Muscle Forces need
Increasing Size of Motor Unit
CNS
CEREBELLUM
SPINAL CORD
Electrical Impulse
Muscle Contraction
Motor Neuron
1 neuron has connection with (<10 for Small and
>1000 For the large calf muscle) Muscle Fibers
MOTOR UNIT
0
25
50
75
100
Motor Unit Recruited (% of maximum)
Initially,
Motor Unit Small in size (1 or 2)
Produced Low Forces
Change in Force is very gradual
Fine Precision Motor Control
DO NOT ATTEMP PRECISE MOVEMENT OR FINE CONTROL IMMEDIATELY
AFTER HEAVY WORK
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(Prinsip Motion Economy 10)
Lifting Heavy Containers Needs
Small Motor Unit and Larger one
Unload : Some Smaller Motor Unit will fatigue
Precise Work :
Some small precise Motor Units are not available
Larger motor Unit recruited to replace the fatigue one
Larger Increments in force, less precise motor Control
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USE BALLISTIC MOVEMENT FOR SPEED
(Prinsip Motion Economy 11)
Agonist
: Penggerak Utama Gerakan
BICEPS
BRACHIORADIALIS
TRICEPS
Antagonist : Melawan
Gerakan
Spinal Reflex, Agonist and antagonist always occur
In Short ( < 200 Msec), the Agonist is activated, the Antagonist is inhibited
Speed
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12. Begin and End Motions With Both Hand Simultaneously
13. Move the Hands Symmetrically and Simultaneously to and from
the Centre of the Body
1. Both hands should not be idle at the same time
2. Both hands can work at the same time, making symmetrical moves
in opposite direction
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14. Use the Natural Rhythms of the Body
Spinal Reflex, Agonist and antagonist always occur
Menyekop
Hentakan kaki
Hentakan tangan
14 – 17 x / menit
60 - 72 x / menit
35 x / menit
15. Use Continuous Curved Motion
Body segment linkage
easier to produce curved motion than straight line
Natural rhythms
16.Use the Lowest Practical Classification of Movement
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Classification :
1.
2.
3.
4.
5.
Finger motion
Finger and wrist motions
Finger, wrist, and lower arm motions
Finger, wrist, lower arm and upper arm motions
Body motion
Longer time
17. Work with Both Hands and feet Simultaneously
By feet if both hands are occupied !
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18. Minimize Eye Fixations
Location of visual target !!
Normal line sight = 150 below the horizontal
Primary visual field = the cone ± 150 in arc centered on the line of sight
EFFECTIVE THERBLIG
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NO
THERBLIG
DESKRIPSI
1
Menjangkau
(Reach)
Gerakan tangan berpindah
tempat tanpa beban
Release
Reach
Grasp
2
Membawa
(Move)
Perpindahan tangan dgn
membawa beban. Grasp
Release / Position
3
Memegang
(Grasp)
Gerakan tangan dengan
menutup objek dgn jari2 tangan
Reach
Grasp
Move
4
Melepas
(Release)
Melepas objek yang dipegang
sebelumnya
Move
EFFECTIVE THERBLIG
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NO
THERBLIG
DESKRIPSI
5
Mengarahkan
Awal
(Pre-Position)
Mengarahkan Objek pada suatu tempat
sementara, Tujuannya adalah untuk
memudahkan pemegangan apabila objek
akan dipakai kembali. Bersamaan dengan
memakai, membawa atau melepas
6
Memakai
(Use)
7
Merakit
(Assemble)
Tangan dipergunakan untuk
memakai/Mengontrol alat/objek dgn
tujuan tertentu
Menggabungkan satu objek dengan yang
lainnya.
Move/Position  Assy  Release
8
Melepas Rakit
(Disassemble)
Objek dipisahkan dari rakitan
Grasp  Disassemble  Move/Release
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NO
1
INEFFECTIVE THERBLIG
THERBLIG
Mencari
(Search)
DESKRIPSI
Menemukan lokasi objek. (Mata atau
tangan.
2
Memilih
(Select)
Menemukan/memilih objek diantara 2
atau lebih objek yang sama lainnya.
Search
Select
3
Mengarahkan
(Position)
Menempatkan objek pada lokasi
yang dituju secara tepat
Move
Position
Assy/ Release
4
Memeriksa
(Inspect)
Membandingkan objek dengan
standar, dgn penglihatan atau indra
lainnya
5
Merencana
(Plan)
Berhenti sejenak bekerja dan
memikirkan untuk menentukan
tindakan-tindakan selanjutnya.
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NO
INEFFECTIVE THERBLIG
THERBLIG
DESKRIPSI
6
Kelambatan Tak Terhindarkan
(Unavoidable Delay) : Diluar kendali operator.
7
Kelambatan yg dapat di hindarkan
(AvoidableDelay)
8
Rest to Overcome fatigue
9
Memegang untuk Memakai (Hold)
Satu tangan memegang objek, yang lain bekerja
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NO
GERAKAN
UPAYA PERBAIKAN DENGAN
MENGHINDARI :
1
Mencari
2
Memilih
3
Memegang
Dipegang Sekaligus? Hanya Kontak?
Memudahkan? Peralatan pembantu ?
4
5
Menjangkau
Membawa
Perpendek?
Perpendek? Efektif?Pemakaian Anggota Tubuh?
Sekaligus? Perubahan Arah GErak? Gravitasi?
6
Melepas
7
Mengarahkan
+membawa?Penampung?Delay setelahnya?
Melepas Sekaligus?
Alat Penuntun? Apakah Diperlukan?
Ciri ? Tata Letak? Pencahayaan? Tempat
Penyimpan Tembus Pandang ?
Objek =, tempat =?, Interchangeability? Tempat
Penyimpanan?
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NO
GERAKAN
UPAYA PERBAIKAN DENGAN
MENGHINDARI :
8
9
10
Mengarahkan Awal
Merencanakan
Memeriksa
11
12
13
14
15
16
17
Merakit
Mengurai Rakit
Memakai
Peralatan pembantu? Sekaligus? Efisien?
Kelambatan Tak Terhindarkan
Kelambatan Terhindarkan
Merencanakan
Istirahat Untuk Melepas Lelah
Digabungkan dengan gerakan lain?
Dihilangkan?Alat Inspeksi? Waktu?