Applied Biomechanics provides insight into biomechanics in relation to the design and construction of devices. It covers topics such as Newtonian mechanics, biomechanical measurement methods, anthropometry, sports, ergonomics, and modeling. Cumulative trauma disorders, also known as repetitive stress injuries, are preventable but not really treatable and are caused by repetitive or forceful motions. The exposure-response-effect model relates the load on the body to biomechanical responses, tolerance levels, and potential injury or disability based on individual factors.

1. Formål
At give indsigt i Biomekanik i relation til design og
Applied
konstruktion af apparater
Indhold
Biomechanics Newton mekanik
Biomekaniske målemetoder
Antropometri
Idræt
http://www.hst.aau.dk/~pm/ab/ab.html
Ergonomi
Modellering
Pascal Madeleine AB
Applied Biomechanics
mm 5 Human factors and systems Applications in Ergonomics
Anthropometri
Concepts
Cumulative trauma disorders –
repetitive stress injuries
mm 7 Applications in Ergonomics
Concepts, cumulative disorders
mm 8 Optimization in Ergonomics
mm7
AB
Pascal Madeleine
Definition
History
Domains of specialization
Holistic approach in which considerations of physical,
Taylor and Gilbreth showed how a task can be cognitive, social, organizational, environmental and
broken down into a number of identifiable, discrete other relevant factors are taken into account.
There exist domains of specialization within the
steps that can be characterized by:
discipline, which represent deeper competencies in
- type of physical motion specific human attributes or characteristics of human
- energy expenditure interaction.
- time required to accomplish the task
- Physical ergonomics
- Cognitive ergonomics
Increase productivity - Organizational ergonomics

2. Definition How the body works in working
situations?
Domains of specialization
Physical ergonomics
Anatomy, physiology, biomechanics, anthropometry, …
The body like en engine – Fueling and cooling system
Cognitive ergonomics moves supplies to combustion sites (muscles and
Memory, computer interface, instrument design, stress, organs) and removes combustion by-products (lactic
user interface, … acid, carbon dioxide,…) for dissipation (skin and
lungs).
Organizational ergonomics
Working situations, rotation,working hours, … Control systems: respiratory system, circulatory
system, metabolic system
Assessment Assessment
of energy of energy
expenditures expenditures
at work at work
Assessment of energy expenditures Assessment
at work of energy
expenditures
at work

3. Exposure-Response-Effect
How the body interacts with Model
the environment?
Load
Physical Individual
Thermoregulation work factors
Biomechanical
Responses
Working in cold
Tolerance
and hot
Organisational
environment factors
Subjective
Air pollution Physiological
Responses Responses
Altitude (Pain, Discomfort)
Noise Social
Injury
context
Gravity
Vibrations Disability
Radiations
…
Exposure-Response-Effect
Model
Pain in Europe
European survey
46,000 interviews
in 16 European Load
countries
Biomechanical
Responses
Tolerance
Subjective Physiological
Responses Responses
(Pain, Discomfort)
Injury
Disability
www.painineurope.com
Cumulative trauma disorders Cumulative trauma disorders
(CTDs) (CTDs)
CTDs is commonly known as work-related disorders of You've heard it called Repetitive Strain Injury (RSI)
the head and upper extremities and are caused when and Carpal Tunnel Syndrome.
there is sufficient stress in a tissue to cause a pathologic It is also known as: Tendinitis, Tennis Elbow or
change in that tissue. Epicondylitis, DeQuervain's Disease, and Thoracic
Examples of common CTD injuries: Outlet Syndrome. It causes pain and discomfort in the
- tendinitis - Carpal Tunnel Syndrome neck, shoulders, wrists, forearms, fingers, elbows, and
- fibromyalgia - synovitis/bursitis back. It can be disabling.
CTDs is the current name for a collections of symptoms
which can be found in the medical literature occurring Not really treatable but it is preventable.
in standardists/musicians from as early the early 1800’s
(Fry, 1986)

4. Cumulative trauma disorders CTDs
(CTDs) CTDs can be divided into separate causative factors:
Use of Excessive Force:
CTD is a wear-and-tear injury to the soft muscle tissue.
Due to inexperience, improper supervision, a belief that more
It is caused by continual stress to specific tendons, force does a better job, competition on the line among workers,
joints, or muscles. Stress is induced by repetition, force, broken or faulty equipment, poorly designed equipment
vibration, and cold. Your body is stressed by daily living
activities. If your body is not able to recover from these Fixed Working Postures:
stressful activities, it will no longer tolerate them. Prolonged periods of static posture.
CTD is linked to work-related activities (writing, Speed of Workers' Movements:
typing, assembly, tool use). Piece or machine-paced work
However, nonoccupational like body weight, pre-
existing injuries, physical fitness, smoking, gender, age Psychosocial Stress
and health conditions (diabetes, arthritis) are of
importance.
CTDs CTDs
Local Fatigue Systemic Fatigue
Listed below are the categories of the body in which the There may be any combination of the following signs
resultant symptomatology is described, due to local and symptoms when systemic fatigue is involved with or
fatigue: without local fatigue, although local almost always
precedes systemic:
• Biomechanical •general feelings of fatigue;
•inability to sleep leading anxiety and/or irritability;
• Tenderness and pain •general feeling of heaviness or lack of mobility;
•general or specific pain that has been described as
• Circulatory problem constant or intermittent dull pain, sharp and/or
shooting sensations.
• Neurophysiological
MMH
Analysis of working
situations
Heavy work (lift)
Repetitive work (ensidigt gentaget arbejde)
Slaughterhouse
–
Refuse collection
–
Computer work
–
Manual material handling
–
Vibrations
…
COLLABORATION WITH ERGOMAT A/S

5. Repetitive work Refuse collection
COLLABORATION WITH AAS COLLABORATION WITH AHTS, R98,…
Computer
work
COLLABORATION WITH SAS
Vibrations
Computer work
COLLABORATION WITH AMI COLLABORATION WITH DSB

6. Model Risk factors
Both physical and psychosocial factors are of interest
and will influence the outcome.
OCCUPATIONAL The known physical factors are:
MOTOR
SETTINGS
- relatively fixed erect posture,
CONTROL
- repetitive arm movements,
- heavy work,
- insufficient rest,
- static posture and
- vibrations
PAIN IN
- cold
DEEP STRUCTURE
Exposure-response-effect (2) Back
(Sjøgaard 1995)
Exposure
-Mental
External Factors -Physical
Internal Factors Acute Response
-ATP-ase
-Actin-Myosin Coupling
-Etc…
Individual
Factors
Long Term Effects
Adaptation WMSD
- Chronic effects
Risk factors Low back pain
Both physical and psychosocial factors are of interest
and will influence the outcome. Pain in lower back coming from the spine, muscles,
nerves, or other structures in that region of your back.
The known physical factors are: It may also radiate from other areas.
- relatively fixed erect posture,
- repetitive arm movements, Variety of symptoms: tingling or burning sensation, a
- heavy work, dull aching, or sharp pain. Evt. weakness in your legs or
- insufficient rest, feet.
- static posture and
- vibrations Not necessarily caused by one event. One may have
been doing many things improperly for a long time.
Then suddenly, one simple movement leads to the
feeling of pain.

7. National institute for
Low back pain
occupational safety and health
(NIOSH) lifting equation
The specific structure in your
back responsible for your pain
is hardly ever identified.
1 The equation and its function
There are several possible sources of low back pain:
2 Task data or variables
* Small fractures to the spine from osteoporosis
* Muscle spasm (very tense muscles that remain contracted) 3 Multipliers
* Ruptured or herniated disk 4 Design/redesign using the recommended weight limit
* Degeneration of the disks
and lifting index
* Poor alignment of the vertebrae
5 Limitations
* Spinal stenosis (narrowing of the spinal canal)
6 Single task and multitasks assessments
* Strain or tears to the muscles or ligaments supporting the
back
Revised 1991 NIOSH Lifting Equation
* Spine curvatures (like scoliosis or kyphosis)
* Other medical conditions like fibromyalgia
THE EQUATION AND ITS THE EQUATION AND ITS
FUNCTION FUNCTION
Recommended Weight Limit (RWL) Recommended Weight Limit (RWL)
The RWL is the weight of the load that nearly all
healthy workers could perform in a specific set of task RWL = LC x HM x VM x DM x AM x FM x CM
conditions over a substantial period of time (eg. up to 8
hours) without an increased risk of developing lifting- Where :
LC Load Constant = 23 kg.
related low back pain.
HM Horizontal Multiplier (distance from object to worker)
Based on a multiplicative model providing a weighting VM Vertical Multiplier (distance from hands to floor)
for each of six task variables. The weightings are DM Distance Multiplier (lift distance)
AM Asymmetric Multiplier (lift asymmetry)
expressed as coefficients that serve to decrease the load
FM Frequency Multiplier (duration and frequency)
constant.
CM Coupling Multiplier (good, medium or bad handgrip)
The load constant represents the maximum The term multipliers refers to the reduction coefficients that
serve to decrease the load constant.
recommended load weight to be lifted under ideal
THE EQUATION AND ITS TASK DATA OR VARIABLES
FUNCTION It refers to the task descriptors (ie. Horizontal location,
Vertical location, Distance of travel, Asymmetric angle,
Lifting index (LI)
Frequency rates and Coupling) that are measurable.
LI provides a relative estimate of the level of physical
stress associated with a particular manual lifting task.
Horizontal Location (H)
Load Weight (L)
LI = H is measured from the mid-point of the line joining the
Recommended Weight Limit (RWL) inner ankle bones to a point projected on the floor
directly below the mid-point of the hand grasps (ie. load
Load Weight (L) = weight of the object lifted.
center), as defined by the large middle knuckle of the
hand.
Lifting tasks with LI>1.0 pose an increased risk for
H should be measured or approximated from the
lifting-related low back pain.
following equations :
If LI=3, nearly all workers risk to develop a work-
1) for V = >25 cm H = 20 cm + W/2
related injury. 2) for V <25 cm H = 25 cm + W/2
Where W is the width of the container in the sagittal plane and V is the

8. TASK DATA TASK DATA OR VARIABLES
OR VARIABLES Vertical Location (V)
V is defined as the vertical location of the hands above
the floor at origin of lift. V is measured vertically from
the floor to the mid-point between the hand grasps, as
defined by the large middle knuckle.
Vertical Travel Distance (D)
D is defined as the vertical travel distance of the hands
between the origin and destination of the lift.
D = V at destination - V at origin
D is assumed to be at least 25 cm, and not greater than
175 cm. If the vertical travel distance is less than 25 cm,
then D should be set to the minimum distance of 25 cm.
TASK DATA OR TASK DATA OR VARIABLES
VARIABLES Lifting Frequency (F)
Asymmetric Angle (A) Average number of lifts per minute, as measured over a
Asymmetry refers to a lift that 15 minute period..
begins or ends outside the mid
-sagittal plane. * If the worker does not lift continuously for 15
A (see fig) defined as the angle minutes, special procedure are needed (see manuals)
between the asymmetry line and
the mid-sagittal line. Coupling (C)
Coupling refers to the relationship between the hands
and the object.
C is classified as good, fair, or poor dependent on the
A is not defined by foot position/torso twist angle, but nature and dimensions of the object and gripping
by the location of the load relative to the worker's mid- method.
sagittal plane.
MULTIPLIERS DESIGN/REDESIGN USING THE
RECOMMENDED WEIGHT LIMIT
The multiplier values can be determined from Tables
AND LIFTING INDEX
Horizontal Multiplier (HM): Table 1.
Vertical Multiplier (VM): Table 2.
Distance Multiplier (DM): Table 3.
Asymmetric Multiplier (AM): Table 4.
Frequency Multiplier (FM): Table 5.
RWL and LI can be used to guide ergonomic design:
Lifting Duration classified as short
, moderate and long duration (Table 6).
Coupling Multiplier (CM): Table 7.
1) The individual multipliers can be used to identify
specific job-related problems (multipliers magnitude
indicates the relative contribution of each factor of the
task)
2) RWL can be used to guide the redesign of existing
manual lifting jobs or to design new manual lifting jobs.
3) LI can be used to estimate the relative magnitude of
physical stress for a job.

9. LIMITATIONS Low back load
The equation does not apply in the following situations
3D dynamic model are becoming
as it could either under - or over-estimate the extent of
more and more common for the
physical stress associated with a particular lifting task :
dynamic description of working
- Lifting/lowering with one hand
tasks.
- Lifting/lowering for over 8 hours
A combination of kinematics and
- Lifting/lowering while seated or kneeling
- Lifting/lowering in a restricted work space kinetic data is used (inversed dynamics) to compute
- Lifting/lowering unstable objects. 1 Lbs = 4.44822162 N
joints load in 3D. 1 inch = 2.54 cm
- Lifting/lowering while carrying, pushing or pulling.
- Lifting/lowering with wheelbarrows or shovels
For the low back, the threshold
- Lifting/lowering with high speed motion
value for compression force in
- Lifting/lowering with unreasonable foot/floor coupling
the lower back should be below
- Lifting/lowering in an unfavourable environment (ie.
temperature and humidity) 3400 N (NIOSH).
Low back load Low back load
F = mg
M=Fd
Moment of muscles=
∑Moments of weights
Hall 1999
Low back load Low back load
Similar physical factors as the ones mentioned
previously (heavy work, lifting, awkward position,
vibration, stamina). Interaction
between chronic
Low-back load is estimated control low-back pain and
via a biomechanical model muscle activity
Evaluation of working during gait
conditions
Design of tools Arendt-Nielsen et al. 1996
Skotte et al. 2002
patient

10. Prevention of low back pain Take home messages
Exercise to improve your posture, strengthen your back
and improve flexibility, Lose weight, Avoid falls
Stretching and strength training. Recommendations:
- Definition
Lift and bend properly.
- Exposure response effect model
* If an object is too heavy or awkward, get help.
- Low back pain & low back load
* Spread your feet apart to give a wide base of support.
* Stand as close to the object you are lifting as possible.
(revised NIOSH lifting equation)
* Bend at your knees, not at your waist.
* Tighten your stomach muscles as you lift the object up or lower it down.
* Hold the object as close to your body as you can.
* Lift using your leg muscles.
* As you stand up with the object, DO NOT bend forward.
* DO NOT twist while you are bending for the object, lifting it up, or carrying it.