The effect on work ability of a tailored ergonomic learning program

Abstract

BACKGROUND:

The physical working conditions and the musculoskeletal health of industrial workers have an effect on their work ability.

OBJECTIVE:

The paper evaluates the effectiveness of an ergonomic learning program focused on the development of low strain working techniques. The project is evaluated in regard to its capacity to improve and sustain the work ability of industrial workers with high physical work demands.

METHOD:

249 employees at an industrial work site were followed over 2½ years. About one third of the employees were selected into differentiated courses according to the severity of musculoskeletal disorders. The reference group consisted of the departments that did not participate. The project was evaluated by using questionnaires and interviews.

RESULTS:

The evaluation of the project only showed minor, non-significant increases in the work ability of the group of employees participating in the most intensive activities. Self- reported productivity increased in all departments, with the largest improvement found among the employees in the department, where everyone participated in a course (8.6% , p = 0.003).

CONCLUSIONS:

Work ability is composed of many different factors, physiological, physical as well as psycho-social and this may explain the only limited results even of the extensive project activities in the present study. However, the evaluation indicated that job rotation in combination with more healthy work methods could sustain the work ability of employees with more severe musculoskeletal disorders.

Keywords

Musculoskeletal pain aging workers working techniques productivity

1 Introduction

The expected increase in the average age of European workers has raised a large concern within the last decade [1 –3]. Decreases in work ability are associated with aging [4] but also an increased risk of both sick leave, early retirement from the labour market [5 –8] as well as difficulty in returning to work after sickness absence [9]. Therefore, there has been a growing attention towards work ability as a measure of the likelihood that workers can stay at work until they reach retirement age.

Physically hazardous working conditions increase the risk of reduced work ability [10 –12], long term sickness absence [13] and early retirement [14, 15]. High physical work demands such as standing up for a long time, doing work which is highly repetitive, lifting heavy loads, working with the hands above the shoulders, or working with the back twisted or bent forward have been found to increase the risk for MSD significantly [16, 17], which in turn increases the risk of reduced work ability [18, 19]. Thus, the link between the physical working conditions and reduced work ability seems to be musculoskeletal disorders. Moreover, among workers with physically heavy work, musculoskeletal disorders most likely affect both work ability and productivity [20].

These problems are prevalent despite the fact that ergonomic amenities have been implemented on most work places within the last few decades. A large amount of work situations still demand both strenuous and repetitive manual work, and 45.5% of the workers within the EU report to be working in painful or tiring positions [21].

One applied strategy towards both musculoskeletal pain and for improving the work ability is orientated towards an increase in the functional capacities of employees through exercise [22 –26]. However, due to the complexity of both musculoskeletal disorders (MSD) and work ability, initiatives to improve the musculoskeletal health and preserve the work ability of workers are likely to be more successful if they target both the employee and the working environment [4 , 27]. For this reason, participatory ergonomics which actively involve the worker in the design of the physical work environment is a recommended strategy for the reduction of MSD [28, 29].

This study evaluates a comprehensive ergonomic learning program in regard to improve and sustain the work ability of a group of industrial workers with high physical work demands. The learning program comprises development of low strain working techniques and task-specific physical training in combination with participatory ergonomics. The overall purpose was to teach the employees how to apply working techniques which do not cause pain or physical deterioration. Since the new working techniques should also be more efficient due to the lesser strain associated with the work, the evaluation included both the effect on work ability and productivity. Participatory ergonomic principles were applied with employees adjusting their physical working station and surroundings according to the new and healthier working techniques.

The project was developed by an experienced physiotherapist, using methods from the field of Spine Theory [30] as well as Motor Learning and Rehabilitation [31, 32]. The evaluation was performed within the framework of a series of work site interventions for prevention of long term loss of work ability due to high physical work demands [33].

2 Method

2.1 Participants

At baseline, the study population consisted of 538 employees, counting both administrative employees and employees in the production line. The employees participated in differentiated versions of the learning program depending on the severity of MSD. The core of the project was courses which were either team based, or intensive and tailored for the individual. The intensive courses were conducted in the first part of the project period.

2.1.1 Data collection and response rates

A structured self-administered questionnaire with validated measures was given to all employees at baseline on August-October 2006, as well as one year after the intensive courses, in October-November 2007, and ½ a year after all teams had completed the final course, in May-April 2009. The questionnaire contained, among other measures, questions from standardized Nordic questionnaires for the analysis of musculoskeletal symptoms [34], work-related factors (e.g. exposure to specific physical work tasks) [35] and a Work ability Scale and Index including chronic diseases and sickness absence [36].

Moreover, the group of employees participating in the intensive courses were interviewed immediately after completion of the course. In the baseline measurement, 448 out of 538 (80%) returned the questionnaire. Of these, 35 persons (7.8%) were working in the administrative unit only and were therefore excluded from further analyses. At the 1st follow up, in October-November 2007, 478 out of 637 (75%) returned the questionnaire. At the 2nd follow up, in May-April 2009, 438 out of 617 (71%) returned the questionnaire. From baseline to 2nd follow up (2½ year) it was possible to match 249 employees. In addition, participants at the intensive courses were interviewed immediately after the courses were finished.

2.1.2 Selection of participants

The employees enrolled in the intensive courses on a voluntary basis after having been given an introduction to the project at a group meeting. All employees with musculoskeletal pain were encouraged to participate. A screening was also carried out before the final selection for these courses. Apart from musculoskeletal pain, the employees own subjective meaning of their proneness to sickness absence due to musculoskeletal problems was a criterion for participation in the project.

The management wished to make the same offer to the employees in the two production departments. Therefore, an equal number of participants from these two departments were enrolled in the courses. Employees with a particular interest in becoming trainers were offered to enroll in the courses as well. This was the case for 4 out of the 31 participants. In the further data analysis, these participants were treated the same way as the other participants. After completion of the intensive courses the management decided that all teams should benefit from the knowledge that had been developed. Therefore, also team courses were conducted in the department which was considered to have the most strenuous physical working conditions (Dep.1), implying that all employees in this department participated in a course. In the other production department (Dep. 2), only intensive courses involving the employees with a high degree of musculoskeletal pain were conducted. In 12 smaller support departments for the two production units, no changes were initiated on individual level and these departments were used as reference group (Ref. group). After the employees had enlisted to participate in an intensive course they were examined by the physiotherapist. Those with acute and longer lasting pain were included while those with radiating pain in upper and lower extremities were excluded.

2.1.3 Measurements of musculoskeletal pain

Musculoskeletal pain was measured as the level of pain intensity on a 0–10 point scale. The following body regions were included: Neck, shoulders, elbows, hands, back, lower back, hips, knees and feet.

2.1.4 Characteristics of the participants

Table 1 presents a summary of descriptive measures for the study population stratified on the two production departments, (Dep. 1 and Dep. 2), and the reference group, (Ref. group). At baseline, 14.1% of the responders were females and 85.9% males. The average age was 43.9 years. The age and gender distribution is similar among the departments. At baseline, the employees in Dep. 1 reported the highest level of musculoskeletal pain intensity, compared to both the employees in Dep. 2 and the Ref. group. In this department, the employees also reported the highest frequency of work with the hands lifted to shoulder height or higher, and repetitive movements with hands and fingers, which were target areas of the project.

There was a significant correlation between working with the hands lifted to shoulder height or higher and shoulder pain for the employees in Dep. 1 (p < 0.05), as well as between doing the same movements with the hands or fingers many times a minute and lower back pain. Among the employees in Ref. group, doing the same movements with the hands or fingers many times a minute was significant correlated to both neck pain and lower back pain (<0.05).

The majority of the employees (61.8%) report their work tasks to be meaningful to a high or a very high degree. Almost all, 94.3% , of the employees are satisfied or very satisfied with their job. The employees in the department a priori considered to have the most strenuous physical working conditions, (Dep. 1), have the highest level of job satisfaction (98.1% satisfied/very satisfied).

2.2 Description of the project

The work place was responsible for the project costs. A physiotherapist led the project as well as designed and conducted the courses. The project design was complex since employees were participating in differentiated courses depending on the severity of MSD they experienced. The employees were supported from the management in the cases where acquiring new helping tools was necessary and the physical work environment was surveyed and continuously adjusted during the project.

The group of employees with a high degree of musculoskeletal pain was given an intensive, individually tailored course, lasting 6 days (30 hours). The courses were conducted in groups of 8 participants and consisted of: 1) individual clinical examinations, 2) analysis of work functions and work related body movements in the actual work situation by recording work method, equipment and body movements on diary films, 3) learning the self treatment of muscle pain, 4) theory about body constitution and functioning, 5) theory about physical laws and rules affecting how work related movements strain the body, 6) learning to be responsible in regard to own musculoskeletal health, 7) coding healthy movements into the body, 8) physical training of balance, strength and coordination, 9) development of new and healthy working techniques, 10) examining the work place interior and work tools.

Team courses lasting from 6 to 9 hours were conducted for the employees in Dep. 1 who were not participating in the intensive courses. To facilitate the process of changing year long accustomed ways of performing specific work tasks with new body routines, the learning process for all course participants started away from the production area, in a training room. Here, awareness of balance, strength and coordination was developed using training equipment and a progressive training plan. After this, body movements involving the least possible degree of strain on the body were trained without any equipment. Finally, the learning process continued in the actual work situation, where low strain body moves were now applied working towards a goal, or task accomplishment. The learning process was also supported by showing a film developed during the intensive courses. The design of the project as well as the effects on MSD of the learning program is reported in detail elsewhere [37].

Essential principles for using the body in a healthy way and avoiding unnecessary strain on muscles and limbs in work situations can be summarized as:

Paying attention to the physical equipment and arrangement of the work station

Choice of correct work tools and helping equipment

Continuous testing and development of work techniques requiring least possible energy

Being aware of body signals (pain i.e.)

Holding loads close to the body when carrying or lifting

Use of the large muscle groups in the legs instead of the smaller muscle groups in the upper body for performing a work task

Use of long and smooth body moves

Doing compensatory physical exercises when having a particular weak muscle group or a job function which puts extra demands on a separate body region

General fitness training including strength exercises

Stretching exercises during the work day and at home if necessary

2.3 Measures

The assessment of work ability was based on the following two questions: “Imagine that your work ability is worth 10 points when it is at its best. How many points would you give your present work ability?” and “How do you perceive your present work ability in relation to the physical demands in your job?” The questions are the first two items in the Work Ability Index, WAI [36].

2.4 Productivity

The question on productivity was posed as follows: “How will you estimate your general work productivity for the last month?” Answers were given on a 1–10 scale. The question is a modified Danish version of the question used for measuring work performance validated in an earlier study [38].

2.5 Statistical design and analyses

Since the study design did not include random selection to the courses, a reference group was formed by the non-administrative workers in the departments not participating in the learning program. This enables us to evaluate if factors at the company level had an impact on the results, and thus increases the internal validity of the study. Also, pre measurements and post measurements were made, and the design can be characterized as quasi-experimental [39].

The statistical analyses are focused on the results from baseline to 2nd follow up, since the project activities between baseline and 1st follow up only included the 31 employees participating in the intensive courses and initiation of changes in the physical work environment. The following tests were set up: 1) For comparison of differences in work ability and productivity (both measured on a 0–10 points scale), between the departments, either paired t-tests or Wilcoxon Signed-Rank test was used. When the differences between the paired observations were normally distributed paired t-test was applied and if the differences between the paired observations were not normally distributed the Wilcoxon Signed-Rank test was used. 2) Binomial tests were used to assess changes in the perception of work ability in relation to the physical demands in the job.

Kendall’s Tau Correlation Coefficient is used for correlation analysis since the variables in the analyses are measured using an ordinal scale.

3 Results

The main results are summarized in Table 2. At baseline, the average self reported work ability is 8.5 points and 44.9% report that their work ability in regard to the physical demands in the job is “very good”. Nobody answered to have poor work ability in relation to the physical demands of the job.

During the project period of 2½ years, there were no significant changes in any of the two work ability measures neither within the departments nor at company level. Productivity however, increased in all departments, with the largest improvement in the department where all employees participated in a course (8.6% , p = 0.003).

Among employees in Dep. 1, the correlation between working with the hands lifted to shoulder height or higher and shoulder pain was not statistically significant at the 2nd follow up. Neither was the correlation between doing the same movements with the hands or fingers many times a minute and lower back pain significant at the 2nd follow up.

Among the employees in the Ref. group, the correlation between doing the same movements with the hands or fingers many times a minute and neck pain was still significant (p < 0.05) at the 2nd follow up while the correlation between doing the same movements with the hands or fingers many times a minute and lower back pain was no longer significant.

3.1 Analysis on the effects of shifting departments

Since the project period was long, turnover and job switches between departments were inevitable. The main analyses accounted for changes between departments within the project period, by using the department attachments at 1st follow up for evaluation of employees not participating in the intensive course, and the department attachments at baseline for evaluating participants in the intensive courses. Changes in work ability were calculated from baseline values to 2nd follow up. The consequence of this allocation is that both the effects of department change and changes in work ability occurring just before an department change influence the results at department level for the participants at team courses. Therefore, additional analyses were performed to evaluate the changes in work ability for: 1) the employees who worked in the same department both at baseline and 1st follow up, and for 2) all employees, using their attachment to departments at baseline, thus also integrating possible effects from shifting department.

Among the employees in the department where all employees participated in a course and who had been attached to the same department for the whole project period, the work ability measured on the 10-point scale was on average 8.6 at baseline and 8.7 at 2nd follow up. For work ability in regard to physical demands, 38.1% answered “Very good” at baseline and 45.2% answered “Very good” at 2nd follow up. On the negative side, at baseline 7.1% employees were in the category of “Reasonable” work ability in regard to physical demands at baseline and at 2nd follow up this number was 11.9% . Among the employees who worked in the same department during the whole project period, 7 employees reported to have increased their work ability in regard to the physical demands and 2 employees reported a decrease in work ability in regard to the physical demands. No employees reported to have poor work ability in regard to the physical demands neither before nor after the project.

In addition, in the department where all employees participated in a course, when using attachment to department at baseline for all employees instead of the attachments at 1st follow up for those not attending the intensive courses (n = 56), work ability measured on the 10-point scale was 8.5 at baseline and 8.8 at 2nd follow up. For the question on work ability in regard to physical demands 39.0% answered “Very good” at baseline and 51.8% answered “Very good” at 2nd follow up (p < 0.05). Here, 6.8% was in the category of “Reasonable” work ability in regard to physical demands at baseline and at 2nd follow up the percentage was 10.7% .

3.2 Experiences from intensive courses

The employees engaging in intensive courses were chosen because of a high degree of musculoskeletal disorders and higher proneness to sickness absence. 29 out of the 31 participants were interviewed by the physiotherapist who lead the project and performed the courses just after the courses were completed. The semi-structured interviews were filmed and subsequently analyzed through qualitative narrative themes based analysis [40]. In table 3 are summarized answers related to the course. Nearly all, (86.2%), stated that they used new working techniques. Also, 34.5% reported to do exercises at home and 20.7% mention the importance of all team members participating in thecourses.

4 Discussion

In this paper, work ability is measured using two single items from the Work Ability Index (WAI) [32]. Other studies have applied single measures for work ability as well and with good results [41, 42]. Despite this, using the work ability index which consists of 7 dimensions of work ability may offer a more through way of evaluating changes in work ability.

When changes in work ability were calculated from baseline to 2nd follow up and effects from job switches between departments were not taken into account, there were no significant changes in any of the work ability measures at department level. Among the employees in the department where all employees participated in a course and who had been attached to the same department for the whole project period, there was a minor improvement in work ability, with a net effect of 5 employees having increased their work ability in regard to the physical demands.

When evaluating changes in work ability using the employees’ attachments to department at baseline, there was a significant improvement in work ability in relation to physical demands for the employees at baseline belonging to the department where all participated in a learning program. This department was also where the physical work environment demanded the most uncomfortable working positions. Therefore, it may be that the combination of the learning program and some employees moving away from the most strenuous work functions has had a positive effect on work ability in relation to physical demands. Or in other words, in order to achieve a significant positive effect on work ability, the willingness of the company to change work demands by moving employees from one department to another, was a necessary supplement to the ergonomic project activities.

In the department where only a part of the employees participated in a course, the mean work ability decreased from 8.9 to 8.4 points. This decrease in work ability may be caused by an increase in musculoskeletal pain occurring in the same period of time. The reason for the increase in MSD among these employees is unknown. It may have been provoked by changes in the psycho-social work environment, such as increased time pressure.

Finding effects on work ability from health interventions in general seem to be difficult. Apart from comprehensive programmes for promoting work ability made in Finland during the last decades [43] only few studies report improvements in work ability from health improving activities. One study showed an improvement in the work ability [44] of elderly bus drivers but only among those who reported an improvement in the quality of the experienced effects from health and ergonomic training. In another study [45] there was an improvement in work ability from short-term and long-term work psychotherapy at a 3-year follow up but no short term effects. Yet other projects have been successful in increasing the functional capacities or physical fitness of a working population but still no effects on work ability were found [27 , 47].

An explanation for the difficulty in improving the work ability levels of employees may be that the previous projects trying to improve work ability have only been targeting single areas of the composite measure of work ability. According to Ilmarinen 2001 [4], single actions like training of supervisors for age management, implementation of age ergonomics, worksite exercise programs and tailored training in new technology can improve work ability during aging. But the results are better if several actions are integrated. During the interviews with the participants at the intensive courses, it was mentioned several times that in the situations where the whole team had participated in the learning program, it was easier to learn the new body movements and to maintain the new and healthy work habits. This, in combination with the productivity rise of 8.6% in the department where all employees had been participating in courses, indicates that the benefits of an ergonomic intervention are largest when all team members are participating in the health promoting activities. Employees in this department had the highest level of job satisfaction at baseline which also may have facilitated the change process.

The large time span of the projects activities made the evaluation more difficult due to turnover and possible loss of motivation to answer the questionnaires used for the evaluation. Moreover, since the period between the intensive courses and 2nd follow up was 2 years while the period between the team courses and the evaluation at 2nd follow up was only 6 months, the maximal effect of the project may not have been reached at the time of the evaluation.

The study was implemented in natural surroundings, which increase the external validity of the results and probably provide a realistic estimate of the benefits that could be expected from a work place initiated ergonomic project. There is an incongruity between the increasing demands for evidence-based practice and the fact that most evidence-based recommendations for behavioural interventions are derived from highly controlled efficacy trials with low external validity [48]. In another study it is argued that practice based research can produce evidence that seems more relevant for health practitioners and reflects the circumstances in which the results of the research are likely to be applied. Here, the authors also point to the trade-off of the experimental control in the practice based studies [49].

An advantage of the intensive education in how to use the body in a healthy way at work is that it will benefit the participating worker for the rest of his or her working life. Also, the project activities are maintained at the work place by a film for training of new employees and by the education of internal trainers. Thus the program aims to perceive lasting public health benefits, and have the capacity to be continued over time by the program sponsors.

4.1 Limitations of the study

The development of low strain working methods in combination with applying participatory ergonomic principles in adjusting the physical work environment did not result in significant increases in the work ability of employees with high physical work demands. Moreover, intensive courses for only employees with more severe musculoskeletal disorders did not offset the negative impact on work ability from other organizational and work related factors imposing additional strain on the employees.

5 Conclusion

Despite minor improvements in the work ability of some groups of employees it was not possible to find any significant, positive effects of the project activities. Work ability is composed of many different factors, physiological, physical as well as psycho-social and this may explain the only limited results even of the extensive project activities in the present study. One of the results of the evaluation was that the benefits of education in low strain working techniques were depending on whether or not all team members participated in the activities. Also, the evaluation indicated that job rotation in combination with more healthy work methods could sustain the work ability of employees with more severe musculoskeletal disorders.

Finally, self reported productivity increased in all departments, with the largest improvement found among the employees in the department, where everyone participated in a course. These results indicate that work ability preserving initiatives also can imply a company gain in productivity if the activities are targeted the specific risk factors in the work, as well as an efficient performing of the work tasks.

Footnotes

Acknowledgements

We thank physiotherapist Anni Vindnæs for her pioneering work in designing and leading the project. The study was performed within the FINALE Program and funded by the Danish Working Environment Research Foundation.

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