Iranian Journal of Ergonomics

Students spend most of their time at school in classrooms, sitting; therefore, the use of inappropriate educational furniture may cause them discomfort and predispose them to musculoskeletal disorders (MSDs) [3].
Field research shows that the spine problem of about 6.75 million German employees is caused by chairs that they sat on for 10 hours a day as a child [7].
Therefore, the aim of this study was to investigate the lack of agreement between anthropometric characteristics of students and dimensions of educational furniture and design and manufacture of ergonomic educational furniture separately based on anthropometric characteristics measured in a sitting position on the campus of Agriculture and Natural Resources, University of Tehran. In this study, with the aim of reducing the possible incompatibility and problems of MSDs and improving the change of physical condition in students, ergonomic educational furniture was designed and made of wooden chairs with double sloping seating and Erasmus desk in accordance with it, which can be another innovation of this research.
 

Figure 1: Anthropometric characteristics measuring equipment a) Anthropometric stadiometer, b) Anthropometric chair

 In this research, 18 anthropometric characteristics including the popliteal height, knee height, shoulder height, eye height, sitting height, elbow support height, elbow height, knotted elbow length, hip-popliteal length, hip-knee length, thigh thickness, abdominal depth, chest depth, hip width, shoulder width, the transverse width of the elbows, height, and as well as weight for 260 students (130 girls and 130 boys) aged 18 to 35 years were investigated. To collect data, an anthropometric chamber and chair were used. The collected data were analyzed using SPSS software version 20 (SPSS Inc., Chicago, IL., USA). Finally, according to the measured physical dimensions of the students, the Dimensions of ergonomic desk and chair were calculated and designed according to the INSO 9697-1 standard.

Figure 2. Schematic images of anthropometric characteristics measured in this study: 1- Popliteal (ridge) height, 2- Sitting knee height, 3- Sitting shoulder height, 4- Sitting eye height, 5- Sitting height, 6- Elbow support height Sitting, 7- Height of sitting elbow, 8- Length of elbow-clenched fist, 9- Length of hip-flexion, 10- Length of hip-sitting knee, 11- Thickness of thigh, 12- Depth of abdomen, 13- Depth of chest, 14- Width Sitting buttocks, 15- shoulder width, 16- elbow width, 17- height
 

Figure 3. Design of separate educational furniture for construction in this research of the type of high chair with a double-sided seat and Erasmus desk


 

Anthropometric dimensions of students were obtained through mean, minimum, maximum, standard deviation, mean, and the percentile value of 2.5 to 97.5 using SPSS version 20 software. The results showed that the age of the user does not have a significant effect on the size of the desk and the chair. Also, the results showed that there was a significant difference in popliteal height between girls and boys.
 

Figure 4. Dimensional guide of a double chair with a slope and a desk suitable for that chair) b1: effective depth of the seat, b2: width of the seat, b3: back width, b4: depth of the front of the seat, b5: depth of the back of the seat, b6: length of the footrest, b7: footrest width, r2: horizontal dorsal radius, h1: seat height, h2: footrest height, h3: point height s, h4: backrest height, b: front seat slope, ɤ: rear seat slope. desk ) H1: desk top surface height, H2: desk top height, L1: desk top surface length, L2: desk top length, W1: desk top surface depth, W2: desk top width, α: desk top surface angle
 

 

Figure 5. A and B) Ergonomic desks and chairs designed and built after determining anthropometric characteristics for boys and girls
Sitting position: c) while writing (active posture), d) while resting and leaning on a chair (inactive posture)
 

Considering the difference in dimensions between female and male students, it was found that the popliteal height in the percentile of 5 for boys is 4 cm more than girls. Therefore, using measured anthropometric characteristics, the dimensions of the chair and desk ergonomics were designed in two sizes.
 

This research was conducted in the form of a master's thesis with the financial support of the scientific deputy of the Faculty of Natural Resources, Campus of Agriculture and Natural Resources, University of Tehran, No. Grant,12-6-30541. The authors of the article consider it necessary to thank and appreciate the cooperation of the Alborz Technical and Vocational Training Center for conducting the best research.

 

The authors declared no conflict of interest.