Understanding and alleviating physical strain in teaching

Understanding and alleviating physical strain in teaching
3 September 2015 frances

Raising awareness for safety and health has only recently been extended to include settings such as those within the educational environment. But in an environment where the two extremes in human stature and ability work and play together, what is being done to promote the health of those responsible for educating our youngest members of society?

As a result of a recent change in political policy in Germany, the number of children under three in nursery schools is constantly increasing. This change in policy is expected to have an effect on the physical workload of nursery school teachers. In light of the policy change and its potential consequences, the German Social Accident Insurance initiated the “ErgoKiTa: Ergonomic design of workplaces in nursery schools” study, which aimed to determine the current situational workload that nursery school teachers are exposed and also identify and evaluate suitable measures for preventing musculoskeletal problems. The research group included experts from the Institute of Ergonomics of the Technical University of Darmstadt, the Institute of Occupational Safety and Health of the German Social Accident Insurance (IFA) and the Institute of Occupational, Social and Environmental Medicine of the Goethe University of Frankfurt, as well as representatives of the social accident insurance institutions of the states of North-Rhine/Westphalia, Rhineland-Palatinate and Hesse.

The fact that facilities in nursery schools are usually designed to be height-appropriate for children often causes the nursery school teacher to adopt unfavourable body postures. Furthermore, with the introduction of children under the age of three into the nursery school environment, task requirements and, in turn, the workload of the staff has been altered. For example, there is an increase in the lifting and carrying of children. As very few studies have focused on the objective musculoskeletal workload in this profession and with the current situational workload being predominantly unknown, important aims of the ErgoKiTa study included identifying potential influencing factors as well as assessing the musculoskeletal strain of nursery school teachers with both subjective and objective methods.

Extensive questionnaires to ascertain the current health of the employees and to assess the structural parameters associated with work organisation, tasks and work environment that may have an effect on the workload were sent to numerous nursery schools selected from the three participating government states. From this pool of nursery schools, nine representative schools from three different German states were selected. These nine nursery schools were classified as having a low, intermediate or high intervention need. These classifications were based on the results from the questionnaires and on workplace inspections that assessed the available facilities and furnishings. As there is limited research pertaining to the workload within this profession, this classification scheme served as a preliminary step to differentiate and assist with the selection of nursery schools that had a greater intervention need based on the available facilities and furnishings, as these factors would most likely effect working posture. These nine nursery schools, specifically selected so that one representative nursery school was selected for each classification group from each of the three German states, were then involved in extensive workload analyses and the intervention study that followed.

To quantify the objective musculoskeletal workload of nursery school teachers, the IFA’s ambulatory computer-assisted recording and long-term analysis of musculoskeletal load for field-based research (CUELA) system, pictured above, was used. This system determines postures and movements from data obtained by accelerometers and gyroscopes. Additional trunk movements such as the torsion of the upper body are recorded as a result of sensors located at the upper and lower body being joined with a metal shaft that is connected to a magnetic field sensor. Loads lifted are assessed using pressure sensitive insoles with piezo-resistive hydro cells, which allowed for the analysis of ground reaction forces, and a biomechanical model. Fitted with this system, each nursery school teacher performing her usual duties in her work environment was analysed for approximately 4 hours during a normal work day on two separate days. In addition to the CUELA system, cardiovascular strain was assessed by recording heart rate, and noise levels were recorded using a noise dosimeter. The data obtained from the sensors were analysed as: duration percentages of unfavourable postures; loads lifted; and the moments and compression forces at the lumbosacral disc L5/S1, for eight hour work shifts and individual tasks. Additionally, the data obtained from the heart rate monitor and noise dosimeter were also analysed in respect to specific tasks as well as for an eight hour work day. The measurement data of the captured physical workloads was synchronised to the video sequences of the corresponding work situations.

The nursery schools were found to differ from one another, between and within the classification schema, with regards to the duration percentages for the different postures for the different tasks as well as for the eight hour work shift. For example, specific nursery schools had a greater percentage of the shift spent in a seated posture where the knee joint was in a position greater than 90°, indicating considerable knee flexion. These data provided an indication of the amount of time the teachers spent seated on children’s chairs at children’s tables. In all the nursery schools, teachers experienced upper body postures with trunk flexion greater than 20° for at least 16% of an eight hour shift. The durations of load bearing activities were noticeably higher in nursery schools with greater numbers of children under the age of three. One nursery school had a class with children only under the age of three and, as result, 4.4% of an eight hour shift contained load bearing activities between 10 and 20kg.

The task analysis showed variations between the different nursery schools for the same tasks with regards to the durations of knee-straining postures. One example of this was for the ‘playing’ task, where postures varied from sitting at a child’s table to playing on the floor with the child.
Based upon the comprehensive work analysis of the nine nursery schools and using a top-down approach, an initial overview of the strain experienced by the different body regions was obtained based on the calculated shift values. In order to determine more concrete areas requiring an intervention, a more detailed analysis of specific tasks was performed. In the final step of the analysis, specific individual examples of situations eliciting high musculoskeletal loads were identified in the video data of the participants. Based on this multi-level approach and in conjunction with additional information obtained through questionnaires and workshops, both situation-orientated prevention measures, such as ergonomic furniture and behavior-orientated prevention measures, such as ergonomics workshops on healthy postures for nursery school teachers, were developed.

The interventions proposed by the study were:

  • Enabling work at different heights to become a “standard”:
  • Children sitting at the height of the educator, educators sitting on the level of children using appropriate furniture, “standing workstations” for children or teachers (e.g. documentation)
  • Anthropometric design: customized dimensions for beds, washing facilities, changing tables
  • Child-appropriate furniture which allows the children to be more independent (e.g. changing table with steps, step stool elements)
  • Reduction of the weight of furniture (e.g. beds)
  • Assistive equipment
  • Organizational measures to promote a change in the task-related physical load (“job rotation”)
  • Ergonomic Behavior-Orientated Training (e.g. “healthy lifting and carrying techniques”)

The results from the ErgoKiTa Project have provided an indication of the musculoskeletal workloads that nursery school teachers may be exposed to on a daily basis and the strain profiles for specific tasks. It has also evaluated prevention measures in order to reduce these strains. These results aim to provide the foundation for the documentation of practical guidelines for ergonomic work design in the nursery school setting. The study indicated that teachers, particularly ones working with young children, experience significant physical strain throughout the day and that intervention and training are needed to protect them from musculoskeletal disorders.

Eva-Maria Burford & Rolf Ellegast

Eva-Maria is a PhD student at Loughborough University. Professor Rolf Ellegast is Deputy Director of The Institute for Occupational Safety and Health of the German Social Accident Insurance.

This article first appeared in The Ergonomist, May 2014.