i want someone to paraphrasing the mine lab i have upland the the lab and the instruction
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Work-related musculoskeletal disorders of the upper and lower extremities are usually
related to manual material handling (Fernandez & Marley, 2007). These disorders are usually
caused from overstrain of the muscles while a task is being performed. In other cases injuries
occur because of awkward postures during the performing of a task. Even though an injury may
not be instantaneous, it can happen over a period of time. A simple task of bending to pick up a
piece of paper could be hazardous depending on the posture of the body. Since it is the job of an
ergonomist to fit a task to a worker and not the vice versa, tasks need to be assessed for their risk
levels in order to protect workers from injuries. The tools that are used to assess the postural risk
of an individual with respect to a task are Job Strain Index (JSI), Rapid Entire Body Assessment
(REBA), and Rapid Upper Limb Assessment (RULA). The objective of this lab is to use the
assessment tools JSI, REBA, and RULA to analyze an individual performing a task.
Methods and Procedure
Device & Apparatus:
In the conduction of this experiment the following were used:
Empty Plastic Case
Job Strain Index (JSI) uses force, repetition, posture, exertion and duration to measure the
risk of injury to the wrist and hands (Hedge). REBA estimates the risk postural of the
entire body (Hedge). RULA measure postural risk related to the upper limb (Hedge).
The subject was told to pick up an empty plastic case weighing about less than 5 lbs.
This had to be done in an awkward posture. In the performance of the task the subject was
videotaped from two different angles (front and side). The screenshot (please see figure 1 and 2)
of the awkward posture was then analyzed using JSI, REBA, and RULA worksheets
Figure 1: Awkward Posture (Front View)
Figure 2: Awkward Posture (Side View)
Results and Discussion
In analyzing the subject performing the task using the JSI (please see Table1: JSI
worksheet), the subject did not have to exert any large amounts of force so the intensity of
exertion (IE) was given an exposure of light. Duration of exertion (DE) was given 20% because
the task was performed for about 10 seconds, with an estimated exertion of about 2 seconds.
This came from about 1 sec of the subject first gripping the case, and the other from the subject
first lifting the case. Efforts per minute (EM) was given a value of 12 because it was perceived
that during the task, there was only two times at which there was any perceived effort even
though it was light. Hand/wrist posture (HWP) was given an exposure of bad because from
looking at the photograph, it was estimated that the right hand was anywhere between 30° – 50°
in flexion. The speed of work (SW) was given an exposure of slow as the subject moved at a
relatively slow pace, but not too slow. Finally, duration per Day (DD) was given an exposure of
8. It was assumed that such a task would have to be performed 8 hours per day. The exposure
data from these six categories are associated with ratings and multipliers, and they were applied
respectively. The JSI was then calculated as the product of all the multipliers which came out to
the total value of 3. Based on the JSI this task is probably safe for the subject to perform. This is
not to say that there is not risk involved.
Table 1: JSI Worksheet
Intensity of Duration of Efforts/ Hand/Wrist
Exertion (IE) Exertion (DE) Minute
Next REBA (please see Table2: REBA worksheet), was used to analyze the task with the
right side of the body being taken into account for the upper arms, lower arms, and wrists. For
group A the trunk was given a score of 5; 4 for the trunk being bent greater than 60° and +1 for
twisting. The neck was given a score of 3; 2 points for the neck > 20° in extension and +1 for
twisting. The legs was given a score of 4; 2 points for an unstable posture since the subject was
bent down leaning over to the right side and 2 points for knees bent > 60° in flexion. For Group
B the upper arms was given a score of 6; 4 points for the arms being > 90° in flexion, +1 for
arms being abducted, and +1 for raised shoulders. The lower arms was given a score of 2 points
assuming it was < 60° in flexion. The wrists was given a score of 3; 2 points for wrist being >
15° in flexion and +1 for twisting.
REBA Table A & Load was then used to calculate the final A score. The trunk, neck and
legs was inputted into the table and produced an output score of 9. Since the case was less than
10 lbs. load/force was given a score of 0 and the final A score was then computed to be 9.
REBA Table B & Coupling was then used to calculate the final B score. The upper arms, lower
arms, and wrists was inputted into the table and produced an output score of 9. The size of the
case with respect to the subject’s hand and the way the case was held did not look good. So 1
point was given for the coupling for a final B score of 10. REBA Table C & Activity score was
then used to calculate the final REBA score. Score A and B was inputted into table C for an
output score of 12. The activity score was given a 1 for rapid change in posture and unstable
base. This produced a final score of 13 which is level 4 in REBA action levels. This action level
says that the risk is high and immediate action should be taken to reduce the risk.
Table 2: REBA Worksheet
Use Table B
Use Table A
Use Table C
Finally RULA (please see Table 3: RULA worksheet) was used to score the subject
performing the task with the right side of the body being taken into account for the upper arm,
lower arm, wrist, and wrist twist. The upper arm were given 5 points; 4 points for the arm being
> 90° and +1 for raised shoulders. The lower arm was given 1 points for being < 90° with respect to the upper. The wrist was given 4 points; 3 for the wrist being > 14° in flexion and +1
for wrist being bent away from midline. Wrist twist was given 1 point for being in mid-range of
twist. The neck was given 5 points; 4 points for it being in extension and +1 for twisting. The
trunk was given a score of 6 points; 4 points for it bending > 60°, +1 for twisting, and +1 for
bending over to the side. The legs were given 2 points because the subject was not well
supported and evenly balanced.
RULA Table A was then used to calculate posture score A. The upper arm, lower arm,
wrist, and wrist twist was inputted into table A to produce an output score of 7. Muscle use was
given 1 point for the A score with the assumption that the task would be repeated at least 4 times
per minute. Force was given a 0 for the A score because it was assumed that the case was < 5 lbs. This produced a final A score of 8 points. RULA Table B was then used to calculate posture score B. The neck, trunk, and legs score was inputted into table B to produce an output score of 6. Muscle use was given 1 point for the B score with the assumption that the task would be repeated at least 4 times per minute. Again, force was given a 0 for the B score because it was assumed that the case was < 5 lbs. This produced a final B score of 7. Score A and B was then inputted into RULA Table C to compute score C (Grand Score) with a total of 7 points.
This final value has an action level of 4 and indicates that investigation and changes are required
Table 3: RULA Worksheet
Posture Score A
Posture Score B
Conclusion and Recommendations
In the analysis both REBA and RULA produced the result that the task was associated
with high risk and required immediate changes. JSI on the other hand produced the result that
the task was probably safe but not without risk, which is kind of ironic. From looking at the way
that the JSI is calculated, it does not take into account the posture of the musculoskeletal system
even though wrist posture is taken into account. It may be that the wrist posture does not carry
enough weight in the JSI point table, so an increase in weight maybe necessary. With respect to
REBA and RULA producing the same result, one way to reduce the risk of the task would be for
the subject to pick up the case when it is directly in front of the subject’s body. It is also
recommended that the subject use their legs to perform the task rather than bending over to pick
up the case. This would cause significant reductions in the risk level associated with the task.
Fernandez, J. E., & Marley, R. J. (2007). Applied occupational ergonomics. (2nd ed.).
Cincinnati: International Journal of Industrial Engineering.
Hedge, A. (n.d.). Cuergo: Jsi. Retrieved from http://ergo.human.cornell.edu/ahJSI.html
Hedge, A. (n.d.). Cuergo: Reba. Retrieved from http://ergo.human.cornell.edu/ahREBA.html
Hedge, A. (n.d.). CUergo: Rula. Retrieved from http://ergo.human.cornell.edu/ahRULA.html
ERGONOMICS AND WORKPLACE DESIGN
Mini Project 2
Video tape or take a still photo of an individual working at a construction site, office
environment, manufacturing environment, or service facility. Analyze the task performed using
JSI (Job Strain Index), REBA (Rapid Entire Body Assessment), and RULA (Rapid Upper Limb
Assessment) tools. Make sure that the task contains some awkward postures of the body parts.
Include the photo in your report.
Format of the report: Same format used for lab. report.
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