Rapid Upper Limb Assessment (RULA)

Prepared by:Isra’a Abu Romman

Project Assignment

Original Study – Literature ReviewRULA ProcedureUsing the RULA – Example step-by-step

guidesAssessment of the validity and

reliability of RULARULA StrengthsRULA LimitationsApplication of RULAConclusion

Table of Contents

RULA Original Study/Literature Review RULA is a posture, force and muscle use

assessment tool developed by McAtamney and Corlett(1993) of University of Nottingham’s Institute for Occupational Ergonomics.

Use in ergonomic investigations of workplaces is a risk of musculoskeletal disorders (MSDs).

The risk factors under investigation are in an effort to assess four external load factors of number of movements, static muscle work, force and postures. RULA focuses on the neck, trunk and upper limbs.

The development of RULA occurred in three phases.

1. Development for the method of recording the working posture

2. Scoring System Development 3. Development of the scale of action levels which provide a guide to the Risk level

RULA Procedure Observing the task and selecting the posture(s) to

assess: The evaluator should prepare for the assessment by

interviewing the worker , understand the job tasks and demands, and observing the worker’s movements and postures during several work cycles.

Selection of the postures to be evaluated should be based on: 1) the most difficult postures and work tasks.

2) the posture sustained for the longest period of time. 3) the posture where the highest force loads occur.

Cont. RULA Procedure Calculate RULA Score determine the

associated Action Level

The traditional RULA sheet [Appendix A] uses body posture diagrams and three scoring tables. The human body is divided in two groups, Group A for upper arm, lower arm, and wrist position, and Group B for neck and trunk analysis. A scoring system is used to assign scores at every level, with a score of 1 indicating the best posture/case.

 

Upper armLower arm

Upper arm

Wrist

Wrist Twist

Neck Trunk Legs

Muscle ActivityMuscle Activity

Loads or forcesLoads or forces

Global Score Group B

Global Score Group A

Using the RULA – Example step-by-step guides To illustrate how RULA scores is calculated

from the RULA traditional worksheet [Appendix A] , I re- producea research results* for

working postures of small scale forging industry in Ludhiana and Jalandhar Region.

* Jaspreet Singh, Harvinder Lal, Gautam Kocher, 2012

Note: In step 1: +3 score was used for upper arm position (45+ degrees) and +1 was added for leaning arm. For step 2: +2 score was given for the lower arm position (<60 degrees) and +1 was added for unsymmetrical position. The step 3 : wrist score was +1 and +1 was added for ulnar deviation. The step 4 wrist score is +2 because the wrist is twisted near the end range.

Note: In step 5: +5 score was used for the neck position in extension and +1 was added for twisted position. The step 6 score is +4 due to a trunk position of > 60 degrees +1 was added for side bent. An in step 7 score is +1 .

Step 8: Add the muscle use score value

Score

Verbal Anchor /Description

0 All Muscle use not describe below

1

Posture that are mainly statics (held for longer than one minute)Repetitive use ( action is repeated more than 4 times/minute.

In this example, the posture is repeated 4x per minute. Therefore, the score is +1.

Step 9: Add the load score value.

In this example, the load is greater than 4.4 lbs. and repeated. Therefore, the score is +2.

Score

Verbal Anchor /Description

0 Weight or force < = 4.4 lbs( 2 kg) and held intermittently

1 Weight or force 4.4 to 22 lbs( 2 to 10 kg) and held intermittently

2

Weight or force 4.4 to 22 lbs( 2 to 10 kg) and held StaticallyWeight or force 4.4 to 22 lbs( 2 to 10 kg) and repetitiveWeight or force >= 22 lbs(10 kg) and held intermittently

3

Weight or force >= 22 lbs(10 kg) and held StaticallyWeight or force >= 22 lbs(10 kg) and repetitiveShock or force with rapid build up

Step 11: Determine the associated Action Level. The requirements for action into which the grand scores are divided is summarized into Action level as illustrated in the following table.Action level

Score Action Required

level I 1-2 Posture is acceptable if it is not maintained or repeated for long periods.

level 2 3-4 Further investigation is needed and changes may be required.

level 3 5-6 Investigation and changes are required soon.

level 4 7+ Investigation and changes are required immediately.

Assessment of the validity and reliability of RULA

McAtamney and Corlett examined the validity and reliability of RULA in their original research by using a data-entry computer task as a model. They investigated the relationship between RULA’s risk categories and psychophysiological measures and used self-reports of perceived discomfort as physical measures.

Cont. RULA assessment

*** Twenty participants with a mean age of 32 (range 21 to 55) each performed a 30-min typing task on a computer in three working postures based on RULA’s scoring system

Leslie J.K Fountian (2003) conducted an experimental research to examine RULA’s postural scoring system with selected physiological and psychophysiological measures (2003)

Cont. RULA aassessmentElectromyography (EMG) as physiological measures

This study used EMG record the electrical activity produced by skeletal muscles to assess musculoskeletal stress associated with awkwardworking postures to reveal of any nerve dysfunction, muscle dysfunction or problems with nerve-to-muscle signal transmission. Six quasi-random samples of EMG were collected for the upper trapezius, anterior deltoid, biceps brachii, and forearm extensors.

Cont. : Psychophysiological MeasuresBody discomfort survey (BDS) Participants were asked to rate their perceived level of discomfort based on a Likert scale of 0 to 7 in body discomfort survey (BDS) where 0 represented no discomfort and 7 represented extreme discomfort.

Job Attitude Questionnaire (JAQ) JAQ used a Likert scale and measured four factors: specific job satisfaction, general job satisfaction, job involvement, and work motivation.

Cont. Assessment of the validity and reliability of RULA methodology Results

In terms of the physiological measures, multi-way repeated measures ANOVA was used to analyses the EMG data. A statistically significant difference was found in performance from posture 1 to 3, as well as posture 2 and 3, but not between postures 1 and 2.

Whereas for perceived psychophysiological measurement for discomfort and performance calculated from the on-site BDS and JAQ, one-way repeated measures ANOVA was used and it’s result demonstrated a significant difference in perceived discomfort and a significant difference in word count across the three working postures.

RULA Strengths RULA still influential in the ergonomic field

No need for special equipment. Quickly and easy to complete without need for

an advanced degree in ergonomics.

RULA scores indicate the level of intervention required to reduce MSD risks.

Perfectly matches the selection criteria for most studies, ideally for sedentary working fields (quantitative, subjective, self reporting potential, posture-based).

RULA Limitations When using RULA, only the right or left side is

assessed at a time

RULA does not include assessment of the fingers and thumb .

RULA does not provide exact engineering controls or work activity change. It gives a total job assessment.

RULA does not provide an integrated assessment of all biomechanical risk factors.

RULA’s scoring system may be too general in nature to differentiate various levels of risk (low, moderate, and high).

Application of RULA Extensive studies have also been

carried out for each risk factor identified for Work related Musculoskeletal disorder (WR-MSD). These studies have been generalized in RULA to make it quick and easy to implement. RULA is ideal for sedentary workers e.g. computer workplaces, service industries. In referred to many researches in the ergonomic field, I summarize a selected interesting application of RULA as following:

RULA and Productivity Optimization

In contrary for those studies that conducted under epidemiological prims, three professors from university of a coruna, spain conducted a study which link ergonomics with productivity.

In this study, RULA analysis is carried out by means of a digital Human Model (DHM) as a tool to simulate the whole proposed design for slate splitter plant. Precise and complete set of tasks and Moves to Posture (MTPS) were evaluated for the current tasks using RULA aiming at quantifying the level of ergonomics risk

Cont. RULA and Productivity Optimization

The operation modelling has involved definition of 80 postures. In summary, I pick the sorting task for illustration purposes.

Sorting Tasks. Grasping and Placing a Lot of Target Plates

Sorting Tasks. Grand Score according to the set of Moves To Posture (MTPs)

Cont. RULA and Productivity Optimization

the plant’s cost and productivity depend largely on the individual performance, The researchers implement their methodology amended upon RULA inputs.

The Proposed Radial Workplace Design

Following figure shows a set of simple improving and reengineering proposed for the work place in terms of ergonomics and productivity.

RULA in Simulation Module. Imtiyaz Shaikh, 2003 integrate RULA algorithm

as ergonomic analysis tool in an immersive environment to study risk factors that identified for work related musculoskeletal disorder.

The assembly process was simulated in a virtual assembly tool (VADE)

As the user goes through the assembly task, his/her motions are monitored by RULA. If the RULA score goes beyond an acceptable value, a warning is flashed to the user as shown in figure 5, so that the user can correct his position.

Cont. RULA in Simulation Module.

Human Model

Ring-assembly Station

RULA warning

Assembly of piston rings- actual assembly plant

RULA Inputs for Ergonomic Intervention Algorithms

Jalil and Nanthanvanij (2008) developed ergonomic intervention algorithms to improve the work posture during laptop operation, mainly this study utilized RULA technique to evaluate work postures both before and after the ergonomic intervention.

Two algorithms were codded in a MATLAB which use anthropometric formulas that use parameters from user’s body part dimensions, physical dimensions of the laptop and workstation constraints., and the output determine the required (x, y) coordinates of body and laptop reference points, then translate it into necessary workstation adjustments.

Cont. RULA Inputs for Ergonomic Intervention Algorithms

Deceased RULA scores from 7 to 3 observed in the work postures after ergonomic rintervention indicate that the adjustment algorithms are effective in helping to improve the laptop users’ work postures.In addition to the quantitative analysis for RULA result, this research collect qualitative feedback from the user themselves, their feedback is extremely in the same tune of RULA results.

Conclusion

RULA is a popular ergonomic assessment method to identify risk factors of the posture, force and muscle risk factors for work related musculoskeletal disorder. RULA considers biomechanical and postural load requirements of job tasks/demands on the neck, trunk and upper extremities.

References [1] McAtamney, L. & Corlett, E.N. (1993), RULA: a survey method for the

investigation of work-related upper limb disorders, Applied Ergonomics, 24, 91-99.

[2] Leslie J.K Fountian (2003), Examining RULA’s Postural Scoring System With Selected Physiological and Psychophysiological Measures, International Journal of Occupational Safety and Ergonomics(JOSE) VOL. 9, NO. 383-392

[3] Jaspreet Singh, Harvinder Lal, Gautam Kocher (2012), Musculoskeletal Disorder Risk Assessment in small scale forging Industry by using RULA Method, International Journal of Engineering and Advanced Technology (IJEAT), ISSN: 2249 – 8958

[4] Shaikh Imtiyaz (2003), Integrating ergonomic analysis functionality with an immersive environmen, Thesis (M.S.)--Washington State University. 

[5] Syazwan Aizat Ismail, Shamsul Bahri Mohd. Tamrin, Mohd. Rafee Baharudin,  Juliana Jalaludin and Zailina Hashim (2010), Evaluation of Two Ergonomics Intervention Programs in Reducing Ergonomics Risk Factors of Musculoskeletal Disorder among School Children,Research Journal of Medical Science 4(1):1-10,2010, ISSN:1815-9346

[6] Nuchrawee Jamjumrus and Suebsak Nanthavanij(2008), Ergonomics Intervention for

Improving Work Postures during Notebook Computer Operation, J. Human Ergol., 37: 23

Thank You

Any Questions!