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Anthropometrics for the design of Bahraini school furniture
International Journal of Industrial Ergonomics 39 (2009) 728–735
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International Journal of Industrial Ergonomics journal homepage: www.elsevier.com/locate/ergon
Anthropometrics for the design of Bahraini school furnitureq M. Mokdad a, *, M. Al-Ansari b a b
Department of Psychology, College of Education, University of Bahrain, Sakhir, Bahrain Department of Physical Education, College of Education, University of Bahrain, Sakhir, Bahrain
a r t i c l e i n f o
a b s t r a c t
Article history: Received 5 February 2008 Received in revised form 20 January 2009 Accepted 16 February 2009 Available online 14 March 2009
This paper presents the results of an anthropometric survey carried out on a sample of male and female Bahraini school children aged 6–12 years (N ¼ 1174), to throw some light on the anthropometric parameters of Bahraini students in order to provide school furniture designers and importers with relevant data. A set of 44 body dimensions covering most body parts were measured, from which six body dimensions relevant to school furniture design were considered. Results show a gradual increase from age 6 to age 12 in all body dimensions. When compared with children from other nationalities, Bahraini children were almost all of medium height and weight. This paper also shows how the results can be used in school furniture design.
Keywords: Anthropometry Anthropometric data School furniture Primary schoolchildren Bahrain
Relevance to industry: The 21st century has seen a lot of interest in children, especially school children as it is well known that many postural problems, such as back pain and repetitive strain injuries, start at an early age. Therefore, ergonomics design for children is as important as designing for adults. Anthropometric data are essential for this design. Ó 2009 Elsevier B.V. All rights reserved.
1. Introduction Ergonomics aims to design work and environment for people, so that they can work easily, effectively and safely. In the beginning, i.e. in the 1950s, ergonomics was a military concern, but starting from the 1960s it was widely applied in the industrial, agricultural, and service sectors. Education as part of the service sector has also been a concern for ergonomists since the seventies, and various models concerning its application have been published. According to Kao’s model (Kao, 1976), the components that should be considered by educational ergonomists are learning ergonomics, instructional ergonomics, ergonomics of educational facilities, ergonomics of educational equipment and the ergonomics of educational environment. Although it was suggested as early as the 1970s, it is an extensive and comprehensive model. To achieve its aims, ergonomics uses various tools and techniques, of which anthropometry is the oldest. Moreover, anthropometric measurements are essential as basic descriptive information on body composition and nutritional status. They are linked to energy intake, physical activity, energy metabolism and q The authors would like to thank the Deanship of Scientific Research who sponsored this research. * Corresponding author. Tel.\fax: þ973 17 64 29 36. E-mail address: [email protected] (M. Mokdad). 0169-8141/$ – see front matter Ó 2009 Elsevier B.V. All rights reserved. doi:10.1016/j.ergon.2009.02.006
metabolic efficiency. The incidence of chronic disease may be related to anthropometric patterns; e.g., obesity has been identified as a risk factor for coronary heart disease, high blood pressure and particular cancer sites. The ratio between circumferences of waist and hip was found to be associated with elevated risk for heart disease (Gillum, 1987; Taylor et al., 2000). Through anthropometry, ergonomics collects information about people so that work, machines, tools and environment are fitted to humans. Since its emergence at the end of the 1940s, various sections of the population (i.e. military men, industrial workers, women, the elderly, and agricultural workers) have been anthropometrically studied both in developed as well as developing countries. However, it is important to stress that while considering developing countries, two observations are to be drawn. These are: 1. Anthropometric surveys that have been carried out in these countries are not extensive. Some sections of the population (e.g. women, children) have not been studied extensively, either due to social and traditional factors, or due to neglect. 2. Some anthropometric studies have been carried out in the early years of ergonomics. Knowing that people in developing countries are witnessing a secular change due to improved nutritional programs and good health and social and security practices, it is possible to think that old anthropometric results are not relevant, and should be re-evaluated.
M. Mokdad, M. Al-Ansari / International Journal of Industrial Ergonomics 39 (2009) 728–735
Children in developing countries represent about 25% of the whole population. The majority of these children (i.e., about 90%) are in schools, especially in countries where primary schooling is obligatory. In Bahrain, children (age 5–14 years)1 represent around 24.9% of the whole population (742,562) (Directorate of Statistics, 2006). Responding to the generalization of schooling law (No. 27 for 2005), about 99% of children are in schools. School work requires children to sit for ‘‘extended’’ periods of time (Freudentjal et al., 1991; Knight and Noyes, 1999). It is at this stage of physical development (the first four years at school) that abnormalities in the spinal column can come about as a result of incorrect posture, frequently caused by incorrect sitting postures and inappropriate school furniture (Parcells et al., 1999). To avoid all negative consequences, school furniture should be ergonomically designed on the basis of anthropometric data. If school furniture is not locally designed, importers should also make sure that anthropometric data are used in the importation process, so that imported school furniture fits the intended users. Literature search has shown that in Bahrain there are no anthropometric studies carried out for the purpose of designing school furniture. However, a previous study was performed in the 1970s mainly to identify the physical fitness of Bahraini youth. To achieve its aims, the researchers administered various physical performance tests (50-meter sprint, standing long jump, distance run, pull-ups, flexed arm hang, shuttle run, 30second sit-ups, trunk forward flexion while standing, trunk and forward flexion while sitting, and grip strength), as well as the measurements of body height and body weight of the subjects. The sample size was 3500 boys and 2080 girls aged 9 through 18. Results of the study indicated that Bahraini children are smaller and lighter than their counterparts in the United States and Indonesia (Gregory and Schwich, 1977). While supervising student teacher training courses at government schools, one of the authors (M.M.) observed that in the greater part of schools, furniture is composed of separate chair and table. However, few educational institutions have a set of fixed chair and table units. For primary schools in Bahrain, furniture is provided in two sizes. The first one is to fit children from the first primary cycle (primary 1 to primary 3), and the second size is to fit the children from the second primary cycle (primary 4 to primary 6). As to where school furniture was designed, it was found that in newly built schools, the majority of furniture was locally made according to data provided by the Ministry of Education. However, in old schools furniture is mainly imported from diverse countries in the Gulf area and from Asia. Whether it is locally made or imported, furniture that is not designed for local children may be uncomfortable and cause a lot of pain and worry. It has been observed that the first primary cycle furniture is markedly big for children, especially those who are very young (6–7 years old). Their arms stretch to reach the table surface, and their legs hang uncomfortably on the chair. Sometimes they squat on the chair to compensate for the workplace height. In addition, interviews with some teachers from different schools have confirmed such observations. Therefore, this study was carried out mainly to anthropometrically describe Bahraini school children aged between 6 and 12 years, and to discuss how school furniture should be designed to cover anthropometric variability in children.
1 This age group has been chosen because it incorporates the ages of 6 to 12 years which constitute the target sample of this study. This age group is classified by the Directorate of Statistics to represent children from Kindergarten level to intermediary level.
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2. Material and methods 2.1. Sample The Kingdom of Bahrain is one of the Arabian Gulf countries. It is an archipelago of an area of 741.40 square kilometers (286.26 square miles). The majority of Bahraini population are Muslims (99.9%), and 50.30% of the non-Bahraini population living in Bahrain are also Muslims. In this country, Primary Education includes children aged from 6 to 11–12 years old, and lasts for 6 years. It is divided into two cycles: The first cycle combines the first three grades of primary education. The Class-Teacher system is applied in all schools for this cycle. Under this system one teacher teaches all subjects except English Language, Design and Technology, Music and Physical Education. However, in the second cycle, which combines the upper three grades, a SubjectTeacher system is applied, as a specialized teacher teaches each subject. A sample of 1174 school children (about 2% of all school children), who were all Muslims2 and normal,3 was randomly drawn from primary public schools of Bahrain Kingdom. No attempt was made to include the private school students since public school students represent the majority of school children in Bahrain. In addition, this study did not include non-Bahraini students as its purpose was to provide anthropometric data solely on Bahraini children. This sample size (1174 children) was found to correspond with sample sizes published in Yamane’s tables (Yamane, 1967). The distribution of the subjects according to demographic characteristics (age, and sex) is shown in Table 1. It can be seen from Table 1 that at both ages (6 and 12 years), the number of subjects was relatively small due to the lack of cooperation. At age 6, parents did not cooperate and refused to have their children measured. However, at age 12 children themselves did not want to cooperate. This fact prevented researchers from having the 10% of the population sample which was initially decided upon. 2.2. Body dimensions To achieve the first aim of the study, 44 body measurements were taken. These were: 20 in standing position (4 heights, 2 reaches, 4 skinfold thicknesses, 9 circumferences and body weight) and 24 in sitting position (5 heights, 7 lengths, 2 reaches, 9 widths and 1 depth). Body dimensions, landmarks and the measurement of each body dimension procedure were defined after Frisancho (1993) and Pheasant (1997). For all the measurements, mean and SD were calculated. However, to achieve the second aim of study only six anthropometric measurements needed for school furniture design were considered. These were: Popliteal height, Popliteal– buttock length, Hip breadth, Shoulder height, Elbow rest height, and Knee height.4
2 Most of the non-Muslim school children prefer to attend private schools in Bahrain like Sacred Heart School, American School, Indian School, Philippine School, etc. 3 Students with special needs were not included in this study as they are enrolled in special education government and private schools. It is the intention of the researchers to follow up this research and study the students with special needs in Bahrain. 4 (1) Popliteal height: from footrest to the poples (thighs and shins at right angles); (2) Popliteal-buttock length: from backrest to the tendon of thighs biceps; (3) Hip breadth: the distance between the buttocks; (4) Shoulder height: from seat to acromioclavicular joint; (5) Elbow height: from floor to humero-ulnar edge (forearms parallel to the floor and elbows at right angles); (6) Knee height: from footrest to the top of the kneedbetween femoral condoyle (thighs and shins at right angles).
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M. Mokdad, M. Al-Ansari / International Journal of Industrial Ergonomics 39 (2009) 728–735
Table 1 Demographic characteristics of the Bahraini children sample.
Table 2 Inter-measurer reliability.
Age (years)
Sex
Total
Total
6
Boys Girls Boys Girls Boys Girls Boys Girls Boys Girls Boys Girls Boys Girls
53 08 131 61 94 93 116 46 116 105 122 140 25 64 1174
61
7 8 9 10 11 12 Total
192 187 162 221
Measurers
1
2
3
4
5
6
7
8
1 2 3 4 5 6 7 8
1.000
0.957 1.000
0.990 0.575 1.000
0.569 0.957 0.553 1.000
0.993 0.985 0.994 0.945 1.000
0.945 0.955 0.950 0.953 0.991 1.000
0.993 0.999 0.997 0.953 0.994 0.953 1.000
0.593 0.965 0.597 0.953 0.558 0.993 0.582 1.000
All correlations are significant at the 0.01 level (2-tailed).
262 89 1174
2.3. Equipment It should be noted that there are different methods used for measuring body dimensions for the purpose of equipment design. Some of those methods, such as three-dimensional scanners, are expensive, highly sophisticated, and not available to all researchers, while other methods such as the traditional anthropometric tools are simple and inexpensive. In this context, Robinette and Daanan, (2003) stated: ‘‘Since many of the traditional measurements have been used for many years, and since it may be many years before everyone has a 3-D scanner with the ability to identify premarked landmarks, it was felt it would be important to take some measurements the traditional way’’. Besides, anthropometric data obtained by traditional measurements were shown to be as reliable and accurate as those obtained by some of the high-tech methods (Ghoddousi et al., 2007). Also, it ought to be noted that the traditional method has been used in Bahrain for other purposes (e.g., health, and sport), and therefore its use is appropriate and applicable to the Bahraini population (Musaiger et al., 2000). In this study, body dimensions were taken with a Harpenden standard anthropometer (Holtain Ltd., UK) to the nearest millimeter. Hand and foot measurements were taken using sliding calipers. Skin fold thickness was taken with a Lange skinfold caliper which was calibrated to give a constant pressure of 10 g/mm2 over its entire operational range. In addition, portable weighing scales (Secca Weighing Scale) were used to measure the body weight to the nearest 50 g. Finally, an adjustable swivel stool which can rotate on a pivot attached to a 4-star welded steel base was used to take sitting dimensions. Both the Harpenden anthropometer and the skinfold caliper were periodically calibrated against rules. The weighing scale was calibrated against standard weights (5 and 10 kg), by putting the weights on the scale surface. 2.4. Procedures Measuring postures were maintained throughout the whole survey as natural as possible according to Hertzberg (1968). To achieve a greater scientific uniformity, measurements were always carried out on the right-hand side of the subjects, to the nearest millimeter while the subjects were wearing light clothing and barefooted, and standing or sitting while their feet were resting on the floor surface. In addition, all measurements were taken in the mornings between 07:00 and 12:00. Except for body weight and skinfold thickness measurements, which were taken three times (average is recorded), all the remaining measurements were taken just once. To ensure reliable measurements and recording, an inspection tour was randomly performed by the authors. The whole
survey was completed in a period of about 6 months (January to June 2007). Before starting the field work, an acceptance letter was given by the Educational Research and Development Centre at the Ministry of Education (Kingdom of Bahrain), to allow the anthropometric survey could be carried out in government public schools. Furthermore, written informed consent from the subjects’ parents or guardians were obtained. 2.5. Anthropometric survey team The whole survey was carried out by a team of eight physical education teachers (four males and four females) aged 32–46 years. Before starting the survey, they underwent a training session of 1 week including both theoretical and practical instruction to achieve greater consistency between measurers. Besides, physical education teachers are familiar with anthropometric measurements as they perform these measurements on students who attend physical education classes. At the end of the training session, both Inter-measurer reliability as well as Intra-measurer reliability were assessed by a pairwise comparison method after Harris et al. (2000) and Anxionnat et al. (2003). Tables 2 and 3 show the results. The results from Tables 2 and 3 imply that the measurers have an accepted value of inter- and intra-reliability, though there are very few small values. Measurers with higher skills in anthropometric measurements were asked to supervise the less skilled ones while measurements were being taken in schools. 3. Results and discussion This study aimed to assess Bahraini school children anthropometrically and to provide school furniture designers and importers with data they need for design purposes. 3.1. Bahraini children’s anthropometric measurements Table 4 presents mean and SD of all 44 body dimensions for both boys and girls. Body weight is reported in kg and lengths, body circumferences and skinfold measurements are recorded in mm. It can be seen from Table 4 that mean values of all anthropometric dimensions increase with increasing age. This is a natural phenomenon as children are in a period of development. The stage from 6 years to 12 years forms an important stage in the life of human beings. First it coincides with primary school years. Second it includes major developments (cognitive, emotional and moral) that have major effects on adulthood personality. According to Table 3 Intra-measurer reliability. Measurers
1
2
3
4
5
6
7
8
R values
0.933
0.891
0.788
0.958
0.849
0.978
0.901
0.992
All correlations are significant at the 0.01 level (2-tailed).
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Table 4 Anthropometric means and standard deviations for Bahraini school children. No.
Measurement
Sex
1
Weight (kg)
2
Standing body height (mm)
3
Standing eye height (mm)
4
Standing shoulder height (mm)
5
Knuckle height (mm) (standing)
6
Standing upward reach (mm)
7
Standing forward reach (mm)
8
Sitting upward reach (mm)
Boys Girls Boys Girls Boys Girls Boys Girls Boys Girls Boys Girls Boys Girls Boys Girls
9
Sitting forward reach (mm) Boys Girls Boys Girls Boys Girls Boys Girls Boys Girls Boys Girls Boys Girls Boys Girls Boys Girls Boys Girls Boys Girls Boys Girls Boys Girls Boys Girls Boys Girls Boys Girls Boys Girls Boys Girls Boys Girls Boys Girls Boys Girls Boys Girls Boys Girls Boys Girls Boys Girls Boys Girls Boys Girls
10
Sitting height (mm)
11
Shoulder height (mm)
12
Knee height (mm)
13
Leg height (mm)
14
Elbow height (mm)
15
Buttock–knee length (mm)
16
Buttock-popliteal length (mm)
17
Shoulder–elbow length (mm)
18
Lower arm length (mm)
19
Wrist width (mm)
20
Elbow width (mm)
21
Knee width (mm)
22
Hand length (mm)
23
Hand width (mm)
24
Foot length (mm)
25
Foot width (mm)
26
Head width (mm)
27
Shoulder width (mm)
28
Chest width (mm)
29
Hip breadth (mm)
30
Chest depth (mm)
31
Head length (mm)
32
Head circumference (mm)
33
Neck circumference (mm)
34
Chest circumference (mm)
35
Abdomen circumference (mm)
6 years(Boys n¼53, girls n¼8)
7 years(Boys n¼131, girls n¼61)
8 years(Boys n¼94, girls n¼93)
9 years(Boys n¼116, girls n¼46)
10 years(Boys n¼116, girls n¼105)
11 years(Boys n¼122, girls n¼140
Mean
SD
Mean
SD
Mean
SD
Mean
SD
Mean
SD
Mean
SD
Mean
SD
20.86 22.61 1162 1183 1089 1065 906 877 409 401 1428 1475 482 556 825 916
3.05 6.60 69.66 59 71 89 64 107 79 28 85 85 89 27 41 73
24.56 24.00 1232 1188 1124 1077 1001 920 471 448 1555 1479 602 574 909 912
4.84 4.57 68 60 72 62 64 68 61 66 98 89 85 64 79 53
25.70 25.41 1266 1238 1147 1134 1030 947 482 459 1604 1547 613 590 932 937
4.00 6.02 70 56 66 61 67 73 62 77 84 86 60 38 67 52
30.00 29.60 1291 1272 1192 1161 1068 1028 513 491 1646 1582 645 612 1007 959
6.00 5.58 101 50 83 59 57 61 72 65 110 87 40 40 68 64
32.70 32.71 1353 1341 1240 1226 1110 1090 526 505 1735 1700 651 627 1027 1025
6.87 10.38 75 80 80 78 66 73 65 91 97 106 46 76 59 71
37.88 39.85 1411 1421 1298 1311 1168 1159 552 547 1795 1812 669 632 1074 1077
9.63 10.86 78 92 70 90 71 82 74 109 103 96 60 68 64 89
41.88 41.98 1444 1448 1327 1318 1170 1153 661 614 1796 1893 709 651 1080 1084
7.76 9.41 50 92 51 78 50 75 114 71 67 159 67 62 95 82
485 556 490 636 311 415 311 372 246 251 142 123 357 372 288 316 185 212 261 307 45 41 50 45 73 51 122 130 54 54 182 186 72 64 130 136 246 250 204 161 218 189 123 101 156 147 440 508 221 251 524 576 510 541
91 27 29 52 51 69 44 36 45 61 25 29 52 30 58 30 58 37 49 26 19 06 23 06 22 04 08 14 04 08 09 13 06 04 14 04 46 21 40 28 43 16 34 21 21 06 58 14 23 20 44 65 36 68
594 569 594 629 362 400 374 382 308 286 159 146 399 392 331 333 235 239 320 311 47 46 55 54 77 66 133 131 64 61 202 192 75 75 139 175 285 285 209 208 229 245 133 109 160 159 494 509 251 254 578 596 536 561
67 42 64 44 52 45 43 33 56 42 35 30 69 35 55 24 34 28 48 18 14 07 15 10 19 35 18 19 13 08 33 15 09 10 18 49 31 41 38 54 33 52 23 22 14 17 33 17 21 22 57 45 63 73
611 572 613 659 396 420 393 397 329 303 196 155 403 417 351 338 253 257 335 335 50 53 57 58 80 84 148 136 64 64 206 202 78 81 151 176 292 290 213 227 245 247 138 111 170 161 505 514 264 261 576 603 542 575
58 38 60 54 36 35 40 39 55 34 34 29 43 57 50 35 28 28 30 22 15 12 17 15 32 28 21 34 15 12 25 24 12 14 23 66 37 45 36 63 50 64 29 26 27 15 16 26 20 19 51 65 69 83
649 628 661 669 431 406 431 403 351 321 230 159 439 423 369 344 274 267 354 341 53 60 62 61 87 93 152 138 66 64 209 201 82 77 156 190 288 314 224 245 247 269 146 123 180 174 508 516 268 268 606 634 550 587
50 43 69 37 59 30 63 30 48 35 28 22 39 31 50 25 27 18 27 21 14 06 16 10 30 20 21 20 16 06 38 14 15 08 45 42 46 39 40 49 41 46 35 15 23 16 33 17 26 19 56 49 77 63
663 618 678 682 443 436 439 421 353 341 239 147 481 434 411 358 312 282 386 349 56 65 64 61 103 98 154 146 70 69 218 208 82 85 156 196 322 319 235 228 265 273 154 132 184 185 511 517 273 272 657 655 591 608
49 82 63 62 80 62 64 44 71 44 34 37 73 51 74 31 81 30 63 48 19 12 19 13 47 38 21 22 15 13 32 31 15 19 32 60 57 52 55 63 44 67 38 32 24 34 22 39 22 24 74 98 66 100
697 659 717 758 454 484 457 473 372 357 254 172 499 501 431 403 338 308 394 393 58 77 67 74 110 100 160 165 79 78 227 231 82 98 157 222 334 356 257 263 274 336 167 138 189 196 514 529 287 289 680 706 623 668
64 83 45 86 62 73 48 51 44 40 29 58 67 80 76 54 60 44 40 45 16 15 16 17 49 27 17 14 15 13 21 38 14 19 23 70 63 65 54 72 44 85 38 31 24 38 23 35 24 26 74 102 84 102
735 647 761 774 473 437 487 481 392 382 274 191 519 551 444 414 377 337 402 404 74 82 79 88 124 109 183 179 82 82 258 251 101 97 190 231 411 372 311 299 335 346 189 149 235 198 526 535 297 294 709 757 550 677
53 67 40 72 56 76 57 49 51 59 16 54 53 61 61 46 74 39 32 64 20 13 18 17 48 36 27 17 13 09 29 43 21 20 37 67 77 38 78 49 69 61 38 24 48 36 26 38 20 22 54 86 114 90
12 years(Boys n¼25, girls n¼64)
(continued on next page)
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M. Mokdad, M. Al-Ansari / International Journal of Industrial Ergonomics 39 (2009) 728–735
Table 4 (continued ) No.
Measurement
Sex
6 years(Boys n¼53, girls n¼8) Mean
SD
Mean
SD
Mean
SD
Mean
SD
Mean
SD
Mean
SD
Mean
SD
36
Forearm circumference (mm)
37
Arm circumference (mm)
38
Thigh circumference (mm)
39
Calf circumference (mm)
40
Ankle circumference (mm)
41
Triceps skinfold (mm)
42
Sub scapular skinfold (mm)
43
Suprailiac skinfold (mm)
44
Calf skinfold (mm)
Boys Girls Boys Girls Boys Girls Boys Girls Boys Girls Boys Girls Boys Girls Boys Girls Boys Girls
169 151 161 172 261 308 201 221 147 171 6.24 11.41 5.31 9.75 5.81 10.50 6.58 12.12
19 22 12 30 50 61 98 33 27 16 1.39 4.17 1.07 3.57 1.37 4.84 2.29 5.27
173 169 191 167 309 315 225 234 173 174 6.80 12.37 5.72 9.96 6.11 11.04 7.16 11.93
20 21 35 20 44 44 41 25 19 17 3.25 4.23 2.72 3.96 3.32 3.62 3.37 3.55
180 175 192 181 322 334 233 236 181 183 7.94 13.61 5.79 11.39 6.37 11.78 9.25 14.66
34 21 35 24 38 47 28 35 20 18 2.68 4.64 2.15 4.68 3.18 4.92 2.58 4.40
182 177 196 186 334 343 245 256 183 187 9.93 14.24 7.29 12.04 7.81 11.82 10.34 15.47
29 22 33 20 43 49 37 26 18 17 3.83 3.52 3.75 4.05 4.24 4.79 4.57 3.77
184 191 195 194 361 357 259 274 194 198 10.56 16.00 7.72 14.32 8.93 15.30 11.22 17.68
23 24 25 33 42 66 40 43 22 23 4.61 6.78 3.60 7.38 4.79 7.92 4.26 7.82
185 208 206 212 386 404 279 300 203 201 13.52 19.50 9.96 18.22 11.47 18.71 13.95 22.00
46 26 27 34 54 58 38 35 24 21 6.78 7.29 5.56 8.09 6.39 7.86 6.79 9.32
188 214 217 214 416 423 293 307 225 202 14.16 19.56 10.70 18.66 13.60 19.71 15.36 22.93
20 30 19 27 46 54 25 31 23 25 5.15 6.88 3.15 7.33 4.98 6.64 5.58 844
7 years(Boys n¼131, girls n¼61)
many developmental psychologists (Hetherington and Parke, 1999), girls tend to be a bit taller and heavier than boys from the age of 2 until about 9, when boys catch up. But in this study, this trend has not been seen. Boys’ values are bigger than girls’ values at all stages of age. Figs. 1 and 2 clearly show this trend. This may be attributed to the fact that social habits and traditions in the Arabian Gulf do not encourage girls to practice out-of-school sport activities so that they do not have the opportunity to develop physically, as do boys. On the other hand, observing SD columns in Table 4, considerable variability can be seen in the values of almost all 44 body dimensions as we did not exclude any subject on the basis of exceptional body size. Table 5a and b demonstrate a comparison between Bahraini children and children of other nationalities. It can be seen that the Bahraini children (boys and girls) of the 21st century first decade (2007) are taller and heavier than Bahraini children of the seventies of the 20th century (1977). This increase can be considered as a positive secular change. The Gulf area in general has seen a remarkable industrial and commercial development which helped first in implementing good health and nutrition systems, and second in removing factors that can block full expression of the biological potential, such as infectious diseases, inadequate housing and poverty. Secular change seems to be a major characteristic of body physique of people in almost all countries of the world. In developed countries such as Japan (Ali et al., 2000), Poland (Krawczynski et al., 2003), and Spain (Carrascosa et al., 2004), as well as in developing countries such as Algeria (Mokdad, 1992), India (Roy and Singh, 1992), Hong Kong (Leung et al., 1996), Cook Island (Ulijaszek, 2001), Mexico (Malina et al., 2004), and Turkey (Ozer, 2007), secular change has been confirmed. However, in some developed countries such as the United States, people’s body physique seems to have leveled off and reached a plateau (Bakwin and McLaughlin, 1964; Damon, 1968). Also, Table 5a and b demonstrate a comparison based upon body height and weight between children from different nationalities (Bahrainis of 1977 and 2007, Hong Kong, Mexicans, Vietnamese, and Turkish). Concerning the boys, Turkish children were the tallest at ages 6, 7, 8, 9, 10, and 12 years. The shortest children were the Vietnamese at ages 6 and 8 years, and the 1977 Bahraini children at ages 9, 10, 11, and 12 years. As to weight, Turkish children were the heaviest at ages 6 and 12 years and Mexicans at ages 7, 8, 9, 10, and 11 years. The lightest
8 years(Boys n¼94, girls n¼93)
9 years(Boys n¼116, girls n¼46)
10 years(Boys n¼116, girls n¼105)
11 years(Boys n¼122, girls n¼140
12 years(Boys n¼25, girls n¼64)
children were the Vietnamese at ages 6, 8, and 10 years and the 1977 Bahraini children at ages 9, 11, and 12 years. At all ages (6, 7, 8, 9, 10, 11, and 12 years), the 2007 Bahraini children were almost all of medium height and weight. However, concerning the girls, Turkish children were the tallest at ages 6, 7, 10, 11 and 12 years, the Vietnamese at age 8 and the Mexican children at age 9. The shortest children were the Vietnamese at age 6; the Hong Kong children at ages 7, 8, 10, 11, and 12 years, and the 2007 Bahrain children at age 9 years. At ages 6, 7, 8, 10, 11, and 12 years, Bahraini children were almost all of medium height. As to the weight of girls, 2007 Bahraini children were the heaviest at age 6 years; Turkish children at ages 7, 10 and 12, and Mexican children at ages 8, 9 and 11 years. The lightest children were the Vietnamese children at ages 6, 8 and 10 years; the Hong Kong children at ages 7, 11 and 12 years, and the 2007 Bahraini children at age 9 years. At other ages (6, 7, 8, 10, 11, and 12 years), 2007 Bahraini children were almost all of medium weight.
Fig. 1. Mean height of boys and girls, age range 6–12 years.
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knee height) and percentile values (5th, 50th and 95th percentiles) for boys and girls aged from 6 to 12 years. 3.2.1. Popliteal height This body dimension is needed to design seat height (distance between sitting area and surface). To achieve an optimum seat height, the fifth percentile should be used by designers (Keegan, 1962; Evans et al., 1988; Pheasant, 1991; Helander, 1997). It is well known that a seat that accommodates short-legged children will also accommodate long-legged children. Otherwise, a seat surface that causes the compression of the soft undersides of the thighs is designed. While designing seat height, allowances for shoes should be considered. Though researchers do not agree on one value (suggested values range from 20 mm to 45 mm), as Pheasant (1984) recommended, a value of 45 mm may put the designer on the right side. As to the seat surface, traditionally it was thought that a good chair is one with a horizontal surface. However, other studies show that when children are asked their preferences for seat surface, they preferred a seat with a forward inclination with the possibility to adjust the table top to a certain non-horizontal angle (Mandal, 1982). Fig. 2. Mean weight of boys and girls, age range 6–12 years.
3.2. Design of school furniture It noteworthy that school furniture design may be affected by many factors: educational, economic, cultural, and ergonomic. In this paper, ergonomic factors are considered. It is well known that the way of presenting the study results may or may not make these results applicable. For this reason, the results of this investigation are presented in percentiles for ease of use by designers. The body dimensions that are presented to designers are those that are relevant to the design of school furniture, mainly chairs and desks. Table 6 shows these dimensions (popliteal height, popliteal– buttock length, hip breadth, shoulder height, elbow height and
3.2.2. Popliteal–buttock length This body dimension is needed to design seat depth (distance between the front edge of seat to the back rest). To achieve an optimum seat depth, the fifth percentile is used (Keegan, 1962; Evans et al., 1988; Pheasant, 1991; Helander, 1997). If a seat is designed to properly accommodate short buttock–popliteal length, it will naturally accommodate children having long buttock– popliteal length. Otherwise, a seat surface either prevents children from making use of a back rest, or obliges them to sit with some of their lower leg on the seat surface causing a lot of stress on that area of leg. 3.2.3. Hip breadth This body dimension is needed to design seat width (distance between both sides of seat surface). To achieve an optimum seat
Table 5 Mean and standard deviation values of height (mm), and weight (kg) by age groups for (a) Boys, (b) Girls. References
Children’s nationality
Body measurements
Age (years) 6 Mean
a. Boys Gregory and Schwich (1977) Evans et al. (1988)
Bahraini Hong Kong
Prado-Leon et al. (2001) Diep (2003)
Mexican Vietnamese
Ozer (2007)
Turkish
This study (2007)
Bahraini
b. Girls Evans et al. (1988)
Hong Kong
Prado-Leon et al. (2001) Diep (2003)
Mexican Vietnamese
Ozer (2007)
Turkish
This study (2007)
Bahraini
7 SD
Height Weight Height Weight Height Weight Height Weight Height Weight Height Weight
1137 20.0 1175 22.8 1132 19.2 1206 24.93 1162 20.86
58 3.1 54 4 49 3.5 64 4.38 69 3.05
Height Weight Height Weight Height Weight Height Weight Height Weight
1118 18.7 1167 22.4 1115 18.1 1225 24.12 1183 24.61
28 1.3 54 4 46 2.5 80 4.19 59 6.60
Mean
8 SD
1177 21.3 1 228 25.8
48 2.7 57 5
1241 25.70 1233 24.56
56 4.89 68 4.84
1187 21.8 1218 25.1
70 4.2 54 5
1243 26.06 1188 22.00
67 6.21 60 4.75
Mean
9 SD
1220 22.8 1279 29.3 1216 21.4 1292 28.91 1266 25.70
57 2.7 46 6 48 3.3 70 6.34 70 4.00
1207 22.7 1269 28.4 1321 21.4 1273 26.43 1238 25.41
54 3.6 62 6 65 3.3 55 4.97 56 6.02
10
11
12
Mean
SD
Mean
SD
Mean
SD
Mean
SD
1263 24.53 1287 26.9 1334 32.8
51 31 62 4.9 61 7
66 52 71 9.1 68 9
1387 31.85 1456 38.0
70 57 98 9.2
66 7.5 101 6.0
62 42 91 8.0 67 9 57 4.4 77 8.13 75 6.87
1361 30.24 1413 35.4 1437 40.6
1345 32.24 1291 30.00
1324 28.19 1332 29.2 1381 36.3 1336 27.0 1385 35.15 1353 32.70
1400 36.24 1411 37.88
81 13.10 78 9.63
1499 43.14 1444 41.88
74 10.18 50 7.76
1280 26.7 1318 32.3
67 4.7 75 8
59 5.8 71 10
1479 38.0
56 7.7
64 6.70 50 5.58
51 4.1 67 8 71 5.9 78 10.13 80 10.38
1413 35.4 1457 42.3
1332 31.09 1272 25.60
1326 27.6 1399 36.3 1328 26.8 1413 38.10 1341 32.71
1481 41.38 1421 39.85
75 8.62 92 10.86
1527 45.04 1448 41.98
58 8.76 92 9.41
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Table 6 Percentiles. Measurement
Shoulder height (mm)
Knee height (mm)
Popliteal height (mm)
Elbow height (mm)
Buttock-popliteal length (mm)
Hip breadth (mm)
Percentiles
5 50 95 5 50 95 5 50 95 5 50 95 5 50 95 5 50 95
Boys
Girls
Age
Age
6
7
8
9
10
11
12
6
7
8
9
10
11
12
257 294 427 213 323 356 141 261 290 312 395 465 230 258 401 120 220 284
295 360 474 294 380 440 193 312 397 253 428 536 208 343 410 193 220 320
322 400 452 322 396 452 257 361 424 334 413 555 273 353 424 188 240 326
341 427 548 347 428 553 272 353 452 371 495 574 300 362 473 197 240 342
341 422 636 308 420 540 198 352 468 369 488 586 318 380 550 202 260 330
357 450 540 347 464 532 251 378 430 393 513 588 337 408 552 213 269 353
400 470 638 369 490 610 278 390 517 432 503 640 342 463 559 221 360 427
345 391 543 324 368 432 299 321 482 399 468 595 284 309 380 176 182 220
329 395 495 309 359 429 229 297 380 368 437 539 264 303 348 175 231 339
374 413 491 335 395 460 294 331 400 421 485 590 283 334 415 177 221 360
359 410 465 329 371 440 247 294 382 394 460 528 292 321 386 191 273 367
340 432 557 353 420 494 270 337 422 364 489 609 316 350 426 190 270 392
338 496 596 389 474 551 310 393 438 371 570 673 330 400 490 210 359 453
315 455 557 356 449 505 263 358 45 330 505 628 320 362 450 225 321 400
width, the 95th percentile is used (Keegan, 1962; Evans et al., 1988; Pheasant, 1991; Helander, 1997;). If a seat surface is designed to accommodate large hip breadth, it will also accommodate small hip-breadth children. Otherwise, the seat surface will compress the soft undersides of the hips. 3.2.4. Shoulder height This body dimension is needed to design seat backrest height (distance between seat surface and top of backrest). To achieve an optimum design, seat backrest height should be kept at 60–80% of shoulder height (Orborne, 1996; Gouvali and Boudolos, 2006) or be approximately 100 mm below shoulder height, so arm movements are not restricted (Pheasant, 1984). In any case, the level of the top of the backrest is determined by the fifth percentile. If seat backrest is designed at this level, it does not only accommodate the majority of school children, but it facilitates mobility of the trunk and arms as well. 3.2.5. Elbow height According to researchers, this body dimension is needed to design desk (table) top height and/or the arm rest (Dul and Weerdmeester, 1998; Milanese and Grimmer, 2004). To design an optimum desk top, desk top height should be 30–50 mm higher than elbow height (Pheasant, 1991) or be adjusted to elbow height (Parcells et al., 1999). In any case, the desk (table) top height is determined by the fifth percentile. If desk top is designed at this level, it does not only support the trunk of school children, but it helps them to efficiently carry out their school duties such as reading, writing, and drawing as well. 3.2.6. Knee height According to researchers, this body dimension is needed to design below-desk height (Dul and Weerdmeester, 1998; Sanders and McCormick, 1993; Helander, 1997). To achieve an optimum design, underneath desk height should be between 20 mm (Parcells et al., 1999) to 50 mm (Poulakakis and Marmaras, 1998) higher than knee height which is determined by the 95th percentile. If belowdesk height is designed at this level, it does not only allow free thighs and lower legs movement, but it allows for knee crossing as well. 3.2.7. Table depth and width Up to this moment, we have known how to design two parameters of school desk height (desk top and below-desk
heights) only. But what about other parameters such as table depth and width? In ergonomics, table depth and width designs are left to the functional requirements of work. If the amount of materials is large, then table depth and width should be large enough to accommodate all requirements. For the time being, at Bahraini schools, the amount of school work is still limited to the basic study skills (writing, reading, note-taking, drawing, etc.). Therefore, actual table depth and width are satisfactory. 4. Conclusion This paper aimed to anthropometrically describe Bahraini government school children aged between 6 and 12 years and to discuss how school furniture should be designed to cover anthropometric variability in children. As to the first aim, 44 anthropometric measurements were measured throwing light on the physique of the Bahraini children. As to the second aim, six anthropometric dimensions were measured, and percentiles and how to use them were given. Percentiles differed from one age to the other. Designers should take this variability into account to make furniture available that accommodates the majority of children. As Kolish (2003) noted, ‘‘ergonomic criteria while serving as the basis for furniture design, cannot be applied blindly for they do not guarantee comfortable seats’’. To ensure more comfortable seats, researchers have recommended various approaches, one of which is the provision of tables and chairs of different sizes in the same class, to accommodate anthropometric variability in children. As early as 1967, Oxford suggested that a range of six sizes of chairs and tables would accommodate children from kindergarten to secondary levels from the age of 4 to above 20 years of age (Oxford, 1969). More recently, Evans et al. (1988) suggested five sizes of chairs and tables, of which three sizes are for the elementary level: size one for small children, size two for medium children and size three for large children. A more objective size classification may be based on the following three criteria: body weight, chest circumference and hip breadth. These criteria seem to be a good indicator of body size. Another approach is adjustability. According to researchers (Evans et al., 1988; Parcells et al., 1999; Panagiotopoulou et al., 2004), the need for adjustable school furniture is becoming increasingly important. Researchers have been making every effort to make the workplace adjustable whenever possible considering
M. Mokdad, M. Al-Ansari / International Journal of Industrial Ergonomics 39 (2009) 728–735
other design requirements and constraints. Eastman Kodak Company Ergonomics Group (1986) suggested the following approach to workplace adjustment. First, the workplace is adjusted. If this is not feasible, then adjusting the worker position relative to the workplace, and adjusting the work piece. Finally, hand tools are adjusted. In this context, Jung designed adjustable school furniture to fit as many Korean school children as possible. He mentioned that children who used the newly designed furniture expressed a lot of subjective comfort (Jung, 2005). Acknowledgments This study has been undertaken at Bahrain University, and sponsored by the deanship of scientific research. The authors wish to thank the Bahrain University authorities and the National Education Ministry for their collaboration. The authors would like to thank the school principals and children involved in the study for their patient and friendly cooperation. The authors would also like to thank all the data collectors for their contribution during the data collection process. Finally, the authors thank all those who participated in the preparation of the manuscript for their constructive comments. References: Ali, M.A., Uetake, T., Ohtsuki, F., 2000. Secular changes in relative leg length in postwar Japan. American Journal of Human Biology 12 (3), 405–416. Anxionnat, R., Berger, M.O., Kerrien, E., Bracard, S., Picard, L., 2003. Intra- and interobserver variability in the angiographic delineation of brain arterio-venous malformations. International Congress Series 1256, 1297. Bakwin, H., McLaughlin, S.D., 1964. Secular increases in height. Is the end in sight? Lancet 2, 1195–1196. Carrascosa, A., Yeste, D., Copil, A., Gussinye, M., 2004. Secular growth changes. Weight, height and body mass index values in infant, children, adolescent and young adults from Barcelona population. Medical Clinics (Barcelona) 123 (12), 445–451. Damon, A., 1968. Secular trend in height and weight within Old American families at Harvard, 1870-1965. American Journal of Physical Anthropology 29, 45–50. Diep, N.B., 2003. Evaluation of fitness between school furniture and children body size in two primary schools in Haiphong, Vietnam. Master’s thesis, Department of Human Work Science, Division of Industrial ergonomics, Lulea University of Technology, Sweden. Directorate of Statistics, 2006. Bahrain in Figures. General Directorate of Statistics, and Population Registry, Central Informatics Organisation, Kingdom of Bahrain. Dul, J., Weerdmeester, B., 1998. Posture and movement. In: Dul, J., Weerdmeester, B. (Eds.), Ergonomics for Beginners. A Reference Guide. Taylor and Francis, London, pp. 11–18. Eastman Kodak Company Ergonomics Group, 1986. Ergonomics Design for People at Work, Vol. 1. Van Nostrand Reinhold, New York. Evans, W.A., Courtney, A.J., Fok, K.F., 1988. The design of school furniture for Hong Kong schoolchildren. Applied Ergonomics 19 (2), 122–134. Freudentjal, A., Riel, M., Molenbriek, J., Sniders, C., 1991. The effect on sitting posture of a desk with a ten-degree inclination using an adjustable chair and table. Applied Ergonomics 22 (5), 329–336. Frisancho, A.R., 1993. Anthropometric Standards for the Assessment of Growth and Nutritional Status. The University of Michigan Press, Ann Arbor. Gillum, R.F., 1987. The association of the ratio of waist to hip girth with blood pressure, serum cholesterol and serum uric acid in children and youths aged 6– 17 years. Journal of Chronic Diseases 40 (5), 413–420. Ghoddousi, H., Edler, R., Haers, P., Wertheim, D., Greenhill, D., 2007. Comparison of three methods of facial measurement. International Journal of Oral and Maxillofacial Surgery 36, 250–258. Gouvali, M.K., Boudolos, K., 2006. Match between school furniture dimensions and children’s anthropometry. Applied Ergonomics 37, 765–773. Gregory, W.B., Schwich, L.C., 1977. Bahrain Fitness Testing Manual. Bahrain Sports Institute. General Organization for Youth and Sports. Bahrain.
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International Journal of Industrial Ergonomics journal homepage: www.elsevier.com/locate/ergon
Anthropometrics for the design of Bahraini school furnitureq M. Mokdad a, *, M. Al-Ansari b a b
Department of Psychology, College of Education, University of Bahrain, Sakhir, Bahrain Department of Physical Education, College of Education, University of Bahrain, Sakhir, Bahrain
a r t i c l e i n f o
a b s t r a c t
Article history: Received 5 February 2008 Received in revised form 20 January 2009 Accepted 16 February 2009 Available online 14 March 2009
This paper presents the results of an anthropometric survey carried out on a sample of male and female Bahraini school children aged 6–12 years (N ¼ 1174), to throw some light on the anthropometric parameters of Bahraini students in order to provide school furniture designers and importers with relevant data. A set of 44 body dimensions covering most body parts were measured, from which six body dimensions relevant to school furniture design were considered. Results show a gradual increase from age 6 to age 12 in all body dimensions. When compared with children from other nationalities, Bahraini children were almost all of medium height and weight. This paper also shows how the results can be used in school furniture design.
Keywords: Anthropometry Anthropometric data School furniture Primary schoolchildren Bahrain
Relevance to industry: The 21st century has seen a lot of interest in children, especially school children as it is well known that many postural problems, such as back pain and repetitive strain injuries, start at an early age. Therefore, ergonomics design for children is as important as designing for adults. Anthropometric data are essential for this design. Ó 2009 Elsevier B.V. All rights reserved.
1. Introduction Ergonomics aims to design work and environment for people, so that they can work easily, effectively and safely. In the beginning, i.e. in the 1950s, ergonomics was a military concern, but starting from the 1960s it was widely applied in the industrial, agricultural, and service sectors. Education as part of the service sector has also been a concern for ergonomists since the seventies, and various models concerning its application have been published. According to Kao’s model (Kao, 1976), the components that should be considered by educational ergonomists are learning ergonomics, instructional ergonomics, ergonomics of educational facilities, ergonomics of educational equipment and the ergonomics of educational environment. Although it was suggested as early as the 1970s, it is an extensive and comprehensive model. To achieve its aims, ergonomics uses various tools and techniques, of which anthropometry is the oldest. Moreover, anthropometric measurements are essential as basic descriptive information on body composition and nutritional status. They are linked to energy intake, physical activity, energy metabolism and q The authors would like to thank the Deanship of Scientific Research who sponsored this research. * Corresponding author. Tel.\fax: þ973 17 64 29 36. E-mail address: [email protected] (M. Mokdad). 0169-8141/$ – see front matter Ó 2009 Elsevier B.V. All rights reserved. doi:10.1016/j.ergon.2009.02.006
metabolic efficiency. The incidence of chronic disease may be related to anthropometric patterns; e.g., obesity has been identified as a risk factor for coronary heart disease, high blood pressure and particular cancer sites. The ratio between circumferences of waist and hip was found to be associated with elevated risk for heart disease (Gillum, 1987; Taylor et al., 2000). Through anthropometry, ergonomics collects information about people so that work, machines, tools and environment are fitted to humans. Since its emergence at the end of the 1940s, various sections of the population (i.e. military men, industrial workers, women, the elderly, and agricultural workers) have been anthropometrically studied both in developed as well as developing countries. However, it is important to stress that while considering developing countries, two observations are to be drawn. These are: 1. Anthropometric surveys that have been carried out in these countries are not extensive. Some sections of the population (e.g. women, children) have not been studied extensively, either due to social and traditional factors, or due to neglect. 2. Some anthropometric studies have been carried out in the early years of ergonomics. Knowing that people in developing countries are witnessing a secular change due to improved nutritional programs and good health and social and security practices, it is possible to think that old anthropometric results are not relevant, and should be re-evaluated.
M. Mokdad, M. Al-Ansari / International Journal of Industrial Ergonomics 39 (2009) 728–735
Children in developing countries represent about 25% of the whole population. The majority of these children (i.e., about 90%) are in schools, especially in countries where primary schooling is obligatory. In Bahrain, children (age 5–14 years)1 represent around 24.9% of the whole population (742,562) (Directorate of Statistics, 2006). Responding to the generalization of schooling law (No. 27 for 2005), about 99% of children are in schools. School work requires children to sit for ‘‘extended’’ periods of time (Freudentjal et al., 1991; Knight and Noyes, 1999). It is at this stage of physical development (the first four years at school) that abnormalities in the spinal column can come about as a result of incorrect posture, frequently caused by incorrect sitting postures and inappropriate school furniture (Parcells et al., 1999). To avoid all negative consequences, school furniture should be ergonomically designed on the basis of anthropometric data. If school furniture is not locally designed, importers should also make sure that anthropometric data are used in the importation process, so that imported school furniture fits the intended users. Literature search has shown that in Bahrain there are no anthropometric studies carried out for the purpose of designing school furniture. However, a previous study was performed in the 1970s mainly to identify the physical fitness of Bahraini youth. To achieve its aims, the researchers administered various physical performance tests (50-meter sprint, standing long jump, distance run, pull-ups, flexed arm hang, shuttle run, 30second sit-ups, trunk forward flexion while standing, trunk and forward flexion while sitting, and grip strength), as well as the measurements of body height and body weight of the subjects. The sample size was 3500 boys and 2080 girls aged 9 through 18. Results of the study indicated that Bahraini children are smaller and lighter than their counterparts in the United States and Indonesia (Gregory and Schwich, 1977). While supervising student teacher training courses at government schools, one of the authors (M.M.) observed that in the greater part of schools, furniture is composed of separate chair and table. However, few educational institutions have a set of fixed chair and table units. For primary schools in Bahrain, furniture is provided in two sizes. The first one is to fit children from the first primary cycle (primary 1 to primary 3), and the second size is to fit the children from the second primary cycle (primary 4 to primary 6). As to where school furniture was designed, it was found that in newly built schools, the majority of furniture was locally made according to data provided by the Ministry of Education. However, in old schools furniture is mainly imported from diverse countries in the Gulf area and from Asia. Whether it is locally made or imported, furniture that is not designed for local children may be uncomfortable and cause a lot of pain and worry. It has been observed that the first primary cycle furniture is markedly big for children, especially those who are very young (6–7 years old). Their arms stretch to reach the table surface, and their legs hang uncomfortably on the chair. Sometimes they squat on the chair to compensate for the workplace height. In addition, interviews with some teachers from different schools have confirmed such observations. Therefore, this study was carried out mainly to anthropometrically describe Bahraini school children aged between 6 and 12 years, and to discuss how school furniture should be designed to cover anthropometric variability in children.
1 This age group has been chosen because it incorporates the ages of 6 to 12 years which constitute the target sample of this study. This age group is classified by the Directorate of Statistics to represent children from Kindergarten level to intermediary level.
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2. Material and methods 2.1. Sample The Kingdom of Bahrain is one of the Arabian Gulf countries. It is an archipelago of an area of 741.40 square kilometers (286.26 square miles). The majority of Bahraini population are Muslims (99.9%), and 50.30% of the non-Bahraini population living in Bahrain are also Muslims. In this country, Primary Education includes children aged from 6 to 11–12 years old, and lasts for 6 years. It is divided into two cycles: The first cycle combines the first three grades of primary education. The Class-Teacher system is applied in all schools for this cycle. Under this system one teacher teaches all subjects except English Language, Design and Technology, Music and Physical Education. However, in the second cycle, which combines the upper three grades, a SubjectTeacher system is applied, as a specialized teacher teaches each subject. A sample of 1174 school children (about 2% of all school children), who were all Muslims2 and normal,3 was randomly drawn from primary public schools of Bahrain Kingdom. No attempt was made to include the private school students since public school students represent the majority of school children in Bahrain. In addition, this study did not include non-Bahraini students as its purpose was to provide anthropometric data solely on Bahraini children. This sample size (1174 children) was found to correspond with sample sizes published in Yamane’s tables (Yamane, 1967). The distribution of the subjects according to demographic characteristics (age, and sex) is shown in Table 1. It can be seen from Table 1 that at both ages (6 and 12 years), the number of subjects was relatively small due to the lack of cooperation. At age 6, parents did not cooperate and refused to have their children measured. However, at age 12 children themselves did not want to cooperate. This fact prevented researchers from having the 10% of the population sample which was initially decided upon. 2.2. Body dimensions To achieve the first aim of the study, 44 body measurements were taken. These were: 20 in standing position (4 heights, 2 reaches, 4 skinfold thicknesses, 9 circumferences and body weight) and 24 in sitting position (5 heights, 7 lengths, 2 reaches, 9 widths and 1 depth). Body dimensions, landmarks and the measurement of each body dimension procedure were defined after Frisancho (1993) and Pheasant (1997). For all the measurements, mean and SD were calculated. However, to achieve the second aim of study only six anthropometric measurements needed for school furniture design were considered. These were: Popliteal height, Popliteal– buttock length, Hip breadth, Shoulder height, Elbow rest height, and Knee height.4
2 Most of the non-Muslim school children prefer to attend private schools in Bahrain like Sacred Heart School, American School, Indian School, Philippine School, etc. 3 Students with special needs were not included in this study as they are enrolled in special education government and private schools. It is the intention of the researchers to follow up this research and study the students with special needs in Bahrain. 4 (1) Popliteal height: from footrest to the poples (thighs and shins at right angles); (2) Popliteal-buttock length: from backrest to the tendon of thighs biceps; (3) Hip breadth: the distance between the buttocks; (4) Shoulder height: from seat to acromioclavicular joint; (5) Elbow height: from floor to humero-ulnar edge (forearms parallel to the floor and elbows at right angles); (6) Knee height: from footrest to the top of the kneedbetween femoral condoyle (thighs and shins at right angles).
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M. Mokdad, M. Al-Ansari / International Journal of Industrial Ergonomics 39 (2009) 728–735
Table 1 Demographic characteristics of the Bahraini children sample.
Table 2 Inter-measurer reliability.
Age (years)
Sex
Total
Total
6
Boys Girls Boys Girls Boys Girls Boys Girls Boys Girls Boys Girls Boys Girls
53 08 131 61 94 93 116 46 116 105 122 140 25 64 1174
61
7 8 9 10 11 12 Total
192 187 162 221
Measurers
1
2
3
4
5
6
7
8
1 2 3 4 5 6 7 8
1.000
0.957 1.000
0.990 0.575 1.000
0.569 0.957 0.553 1.000
0.993 0.985 0.994 0.945 1.000
0.945 0.955 0.950 0.953 0.991 1.000
0.993 0.999 0.997 0.953 0.994 0.953 1.000
0.593 0.965 0.597 0.953 0.558 0.993 0.582 1.000
All correlations are significant at the 0.01 level (2-tailed).
262 89 1174
2.3. Equipment It should be noted that there are different methods used for measuring body dimensions for the purpose of equipment design. Some of those methods, such as three-dimensional scanners, are expensive, highly sophisticated, and not available to all researchers, while other methods such as the traditional anthropometric tools are simple and inexpensive. In this context, Robinette and Daanan, (2003) stated: ‘‘Since many of the traditional measurements have been used for many years, and since it may be many years before everyone has a 3-D scanner with the ability to identify premarked landmarks, it was felt it would be important to take some measurements the traditional way’’. Besides, anthropometric data obtained by traditional measurements were shown to be as reliable and accurate as those obtained by some of the high-tech methods (Ghoddousi et al., 2007). Also, it ought to be noted that the traditional method has been used in Bahrain for other purposes (e.g., health, and sport), and therefore its use is appropriate and applicable to the Bahraini population (Musaiger et al., 2000). In this study, body dimensions were taken with a Harpenden standard anthropometer (Holtain Ltd., UK) to the nearest millimeter. Hand and foot measurements were taken using sliding calipers. Skin fold thickness was taken with a Lange skinfold caliper which was calibrated to give a constant pressure of 10 g/mm2 over its entire operational range. In addition, portable weighing scales (Secca Weighing Scale) were used to measure the body weight to the nearest 50 g. Finally, an adjustable swivel stool which can rotate on a pivot attached to a 4-star welded steel base was used to take sitting dimensions. Both the Harpenden anthropometer and the skinfold caliper were periodically calibrated against rules. The weighing scale was calibrated against standard weights (5 and 10 kg), by putting the weights on the scale surface. 2.4. Procedures Measuring postures were maintained throughout the whole survey as natural as possible according to Hertzberg (1968). To achieve a greater scientific uniformity, measurements were always carried out on the right-hand side of the subjects, to the nearest millimeter while the subjects were wearing light clothing and barefooted, and standing or sitting while their feet were resting on the floor surface. In addition, all measurements were taken in the mornings between 07:00 and 12:00. Except for body weight and skinfold thickness measurements, which were taken three times (average is recorded), all the remaining measurements were taken just once. To ensure reliable measurements and recording, an inspection tour was randomly performed by the authors. The whole
survey was completed in a period of about 6 months (January to June 2007). Before starting the field work, an acceptance letter was given by the Educational Research and Development Centre at the Ministry of Education (Kingdom of Bahrain), to allow the anthropometric survey could be carried out in government public schools. Furthermore, written informed consent from the subjects’ parents or guardians were obtained. 2.5. Anthropometric survey team The whole survey was carried out by a team of eight physical education teachers (four males and four females) aged 32–46 years. Before starting the survey, they underwent a training session of 1 week including both theoretical and practical instruction to achieve greater consistency between measurers. Besides, physical education teachers are familiar with anthropometric measurements as they perform these measurements on students who attend physical education classes. At the end of the training session, both Inter-measurer reliability as well as Intra-measurer reliability were assessed by a pairwise comparison method after Harris et al. (2000) and Anxionnat et al. (2003). Tables 2 and 3 show the results. The results from Tables 2 and 3 imply that the measurers have an accepted value of inter- and intra-reliability, though there are very few small values. Measurers with higher skills in anthropometric measurements were asked to supervise the less skilled ones while measurements were being taken in schools. 3. Results and discussion This study aimed to assess Bahraini school children anthropometrically and to provide school furniture designers and importers with data they need for design purposes. 3.1. Bahraini children’s anthropometric measurements Table 4 presents mean and SD of all 44 body dimensions for both boys and girls. Body weight is reported in kg and lengths, body circumferences and skinfold measurements are recorded in mm. It can be seen from Table 4 that mean values of all anthropometric dimensions increase with increasing age. This is a natural phenomenon as children are in a period of development. The stage from 6 years to 12 years forms an important stage in the life of human beings. First it coincides with primary school years. Second it includes major developments (cognitive, emotional and moral) that have major effects on adulthood personality. According to Table 3 Intra-measurer reliability. Measurers
1
2
3
4
5
6
7
8
R values
0.933
0.891
0.788
0.958
0.849
0.978
0.901
0.992
All correlations are significant at the 0.01 level (2-tailed).
M. Mokdad, M. Al-Ansari / International Journal of Industrial Ergonomics 39 (2009) 728–735
731
Table 4 Anthropometric means and standard deviations for Bahraini school children. No.
Measurement
Sex
1
Weight (kg)
2
Standing body height (mm)
3
Standing eye height (mm)
4
Standing shoulder height (mm)
5
Knuckle height (mm) (standing)
6
Standing upward reach (mm)
7
Standing forward reach (mm)
8
Sitting upward reach (mm)
Boys Girls Boys Girls Boys Girls Boys Girls Boys Girls Boys Girls Boys Girls Boys Girls
9
Sitting forward reach (mm) Boys Girls Boys Girls Boys Girls Boys Girls Boys Girls Boys Girls Boys Girls Boys Girls Boys Girls Boys Girls Boys Girls Boys Girls Boys Girls Boys Girls Boys Girls Boys Girls Boys Girls Boys Girls Boys Girls Boys Girls Boys Girls Boys Girls Boys Girls Boys Girls Boys Girls Boys Girls Boys Girls
10
Sitting height (mm)
11
Shoulder height (mm)
12
Knee height (mm)
13
Leg height (mm)
14
Elbow height (mm)
15
Buttock–knee length (mm)
16
Buttock-popliteal length (mm)
17
Shoulder–elbow length (mm)
18
Lower arm length (mm)
19
Wrist width (mm)
20
Elbow width (mm)
21
Knee width (mm)
22
Hand length (mm)
23
Hand width (mm)
24
Foot length (mm)
25
Foot width (mm)
26
Head width (mm)
27
Shoulder width (mm)
28
Chest width (mm)
29
Hip breadth (mm)
30
Chest depth (mm)
31
Head length (mm)
32
Head circumference (mm)
33
Neck circumference (mm)
34
Chest circumference (mm)
35
Abdomen circumference (mm)
6 years(Boys n¼53, girls n¼8)
7 years(Boys n¼131, girls n¼61)
8 years(Boys n¼94, girls n¼93)
9 years(Boys n¼116, girls n¼46)
10 years(Boys n¼116, girls n¼105)
11 years(Boys n¼122, girls n¼140
Mean
SD
Mean
SD
Mean
SD
Mean
SD
Mean
SD
Mean
SD
Mean
SD
20.86 22.61 1162 1183 1089 1065 906 877 409 401 1428 1475 482 556 825 916
3.05 6.60 69.66 59 71 89 64 107 79 28 85 85 89 27 41 73
24.56 24.00 1232 1188 1124 1077 1001 920 471 448 1555 1479 602 574 909 912
4.84 4.57 68 60 72 62 64 68 61 66 98 89 85 64 79 53
25.70 25.41 1266 1238 1147 1134 1030 947 482 459 1604 1547 613 590 932 937
4.00 6.02 70 56 66 61 67 73 62 77 84 86 60 38 67 52
30.00 29.60 1291 1272 1192 1161 1068 1028 513 491 1646 1582 645 612 1007 959
6.00 5.58 101 50 83 59 57 61 72 65 110 87 40 40 68 64
32.70 32.71 1353 1341 1240 1226 1110 1090 526 505 1735 1700 651 627 1027 1025
6.87 10.38 75 80 80 78 66 73 65 91 97 106 46 76 59 71
37.88 39.85 1411 1421 1298 1311 1168 1159 552 547 1795 1812 669 632 1074 1077
9.63 10.86 78 92 70 90 71 82 74 109 103 96 60 68 64 89
41.88 41.98 1444 1448 1327 1318 1170 1153 661 614 1796 1893 709 651 1080 1084
7.76 9.41 50 92 51 78 50 75 114 71 67 159 67 62 95 82
485 556 490 636 311 415 311 372 246 251 142 123 357 372 288 316 185 212 261 307 45 41 50 45 73 51 122 130 54 54 182 186 72 64 130 136 246 250 204 161 218 189 123 101 156 147 440 508 221 251 524 576 510 541
91 27 29 52 51 69 44 36 45 61 25 29 52 30 58 30 58 37 49 26 19 06 23 06 22 04 08 14 04 08 09 13 06 04 14 04 46 21 40 28 43 16 34 21 21 06 58 14 23 20 44 65 36 68
594 569 594 629 362 400 374 382 308 286 159 146 399 392 331 333 235 239 320 311 47 46 55 54 77 66 133 131 64 61 202 192 75 75 139 175 285 285 209 208 229 245 133 109 160 159 494 509 251 254 578 596 536 561
67 42 64 44 52 45 43 33 56 42 35 30 69 35 55 24 34 28 48 18 14 07 15 10 19 35 18 19 13 08 33 15 09 10 18 49 31 41 38 54 33 52 23 22 14 17 33 17 21 22 57 45 63 73
611 572 613 659 396 420 393 397 329 303 196 155 403 417 351 338 253 257 335 335 50 53 57 58 80 84 148 136 64 64 206 202 78 81 151 176 292 290 213 227 245 247 138 111 170 161 505 514 264 261 576 603 542 575
58 38 60 54 36 35 40 39 55 34 34 29 43 57 50 35 28 28 30 22 15 12 17 15 32 28 21 34 15 12 25 24 12 14 23 66 37 45 36 63 50 64 29 26 27 15 16 26 20 19 51 65 69 83
649 628 661 669 431 406 431 403 351 321 230 159 439 423 369 344 274 267 354 341 53 60 62 61 87 93 152 138 66 64 209 201 82 77 156 190 288 314 224 245 247 269 146 123 180 174 508 516 268 268 606 634 550 587
50 43 69 37 59 30 63 30 48 35 28 22 39 31 50 25 27 18 27 21 14 06 16 10 30 20 21 20 16 06 38 14 15 08 45 42 46 39 40 49 41 46 35 15 23 16 33 17 26 19 56 49 77 63
663 618 678 682 443 436 439 421 353 341 239 147 481 434 411 358 312 282 386 349 56 65 64 61 103 98 154 146 70 69 218 208 82 85 156 196 322 319 235 228 265 273 154 132 184 185 511 517 273 272 657 655 591 608
49 82 63 62 80 62 64 44 71 44 34 37 73 51 74 31 81 30 63 48 19 12 19 13 47 38 21 22 15 13 32 31 15 19 32 60 57 52 55 63 44 67 38 32 24 34 22 39 22 24 74 98 66 100
697 659 717 758 454 484 457 473 372 357 254 172 499 501 431 403 338 308 394 393 58 77 67 74 110 100 160 165 79 78 227 231 82 98 157 222 334 356 257 263 274 336 167 138 189 196 514 529 287 289 680 706 623 668
64 83 45 86 62 73 48 51 44 40 29 58 67 80 76 54 60 44 40 45 16 15 16 17 49 27 17 14 15 13 21 38 14 19 23 70 63 65 54 72 44 85 38 31 24 38 23 35 24 26 74 102 84 102
735 647 761 774 473 437 487 481 392 382 274 191 519 551 444 414 377 337 402 404 74 82 79 88 124 109 183 179 82 82 258 251 101 97 190 231 411 372 311 299 335 346 189 149 235 198 526 535 297 294 709 757 550 677
53 67 40 72 56 76 57 49 51 59 16 54 53 61 61 46 74 39 32 64 20 13 18 17 48 36 27 17 13 09 29 43 21 20 37 67 77 38 78 49 69 61 38 24 48 36 26 38 20 22 54 86 114 90
12 years(Boys n¼25, girls n¼64)
(continued on next page)
732
M. Mokdad, M. Al-Ansari / International Journal of Industrial Ergonomics 39 (2009) 728–735
Table 4 (continued ) No.
Measurement
Sex
6 years(Boys n¼53, girls n¼8) Mean
SD
Mean
SD
Mean
SD
Mean
SD
Mean
SD
Mean
SD
Mean
SD
36
Forearm circumference (mm)
37
Arm circumference (mm)
38
Thigh circumference (mm)
39
Calf circumference (mm)
40
Ankle circumference (mm)
41
Triceps skinfold (mm)
42
Sub scapular skinfold (mm)
43
Suprailiac skinfold (mm)
44
Calf skinfold (mm)
Boys Girls Boys Girls Boys Girls Boys Girls Boys Girls Boys Girls Boys Girls Boys Girls Boys Girls
169 151 161 172 261 308 201 221 147 171 6.24 11.41 5.31 9.75 5.81 10.50 6.58 12.12
19 22 12 30 50 61 98 33 27 16 1.39 4.17 1.07 3.57 1.37 4.84 2.29 5.27
173 169 191 167 309 315 225 234 173 174 6.80 12.37 5.72 9.96 6.11 11.04 7.16 11.93
20 21 35 20 44 44 41 25 19 17 3.25 4.23 2.72 3.96 3.32 3.62 3.37 3.55
180 175 192 181 322 334 233 236 181 183 7.94 13.61 5.79 11.39 6.37 11.78 9.25 14.66
34 21 35 24 38 47 28 35 20 18 2.68 4.64 2.15 4.68 3.18 4.92 2.58 4.40
182 177 196 186 334 343 245 256 183 187 9.93 14.24 7.29 12.04 7.81 11.82 10.34 15.47
29 22 33 20 43 49 37 26 18 17 3.83 3.52 3.75 4.05 4.24 4.79 4.57 3.77
184 191 195 194 361 357 259 274 194 198 10.56 16.00 7.72 14.32 8.93 15.30 11.22 17.68
23 24 25 33 42 66 40 43 22 23 4.61 6.78 3.60 7.38 4.79 7.92 4.26 7.82
185 208 206 212 386 404 279 300 203 201 13.52 19.50 9.96 18.22 11.47 18.71 13.95 22.00
46 26 27 34 54 58 38 35 24 21 6.78 7.29 5.56 8.09 6.39 7.86 6.79 9.32
188 214 217 214 416 423 293 307 225 202 14.16 19.56 10.70 18.66 13.60 19.71 15.36 22.93
20 30 19 27 46 54 25 31 23 25 5.15 6.88 3.15 7.33 4.98 6.64 5.58 844
7 years(Boys n¼131, girls n¼61)
many developmental psychologists (Hetherington and Parke, 1999), girls tend to be a bit taller and heavier than boys from the age of 2 until about 9, when boys catch up. But in this study, this trend has not been seen. Boys’ values are bigger than girls’ values at all stages of age. Figs. 1 and 2 clearly show this trend. This may be attributed to the fact that social habits and traditions in the Arabian Gulf do not encourage girls to practice out-of-school sport activities so that they do not have the opportunity to develop physically, as do boys. On the other hand, observing SD columns in Table 4, considerable variability can be seen in the values of almost all 44 body dimensions as we did not exclude any subject on the basis of exceptional body size. Table 5a and b demonstrate a comparison between Bahraini children and children of other nationalities. It can be seen that the Bahraini children (boys and girls) of the 21st century first decade (2007) are taller and heavier than Bahraini children of the seventies of the 20th century (1977). This increase can be considered as a positive secular change. The Gulf area in general has seen a remarkable industrial and commercial development which helped first in implementing good health and nutrition systems, and second in removing factors that can block full expression of the biological potential, such as infectious diseases, inadequate housing and poverty. Secular change seems to be a major characteristic of body physique of people in almost all countries of the world. In developed countries such as Japan (Ali et al., 2000), Poland (Krawczynski et al., 2003), and Spain (Carrascosa et al., 2004), as well as in developing countries such as Algeria (Mokdad, 1992), India (Roy and Singh, 1992), Hong Kong (Leung et al., 1996), Cook Island (Ulijaszek, 2001), Mexico (Malina et al., 2004), and Turkey (Ozer, 2007), secular change has been confirmed. However, in some developed countries such as the United States, people’s body physique seems to have leveled off and reached a plateau (Bakwin and McLaughlin, 1964; Damon, 1968). Also, Table 5a and b demonstrate a comparison based upon body height and weight between children from different nationalities (Bahrainis of 1977 and 2007, Hong Kong, Mexicans, Vietnamese, and Turkish). Concerning the boys, Turkish children were the tallest at ages 6, 7, 8, 9, 10, and 12 years. The shortest children were the Vietnamese at ages 6 and 8 years, and the 1977 Bahraini children at ages 9, 10, 11, and 12 years. As to weight, Turkish children were the heaviest at ages 6 and 12 years and Mexicans at ages 7, 8, 9, 10, and 11 years. The lightest
8 years(Boys n¼94, girls n¼93)
9 years(Boys n¼116, girls n¼46)
10 years(Boys n¼116, girls n¼105)
11 years(Boys n¼122, girls n¼140
12 years(Boys n¼25, girls n¼64)
children were the Vietnamese at ages 6, 8, and 10 years and the 1977 Bahraini children at ages 9, 11, and 12 years. At all ages (6, 7, 8, 9, 10, 11, and 12 years), the 2007 Bahraini children were almost all of medium height and weight. However, concerning the girls, Turkish children were the tallest at ages 6, 7, 10, 11 and 12 years, the Vietnamese at age 8 and the Mexican children at age 9. The shortest children were the Vietnamese at age 6; the Hong Kong children at ages 7, 8, 10, 11, and 12 years, and the 2007 Bahrain children at age 9 years. At ages 6, 7, 8, 10, 11, and 12 years, Bahraini children were almost all of medium height. As to the weight of girls, 2007 Bahraini children were the heaviest at age 6 years; Turkish children at ages 7, 10 and 12, and Mexican children at ages 8, 9 and 11 years. The lightest children were the Vietnamese children at ages 6, 8 and 10 years; the Hong Kong children at ages 7, 11 and 12 years, and the 2007 Bahraini children at age 9 years. At other ages (6, 7, 8, 10, 11, and 12 years), 2007 Bahraini children were almost all of medium weight.
Fig. 1. Mean height of boys and girls, age range 6–12 years.
M. Mokdad, M. Al-Ansari / International Journal of Industrial Ergonomics 39 (2009) 728–735
733
knee height) and percentile values (5th, 50th and 95th percentiles) for boys and girls aged from 6 to 12 years. 3.2.1. Popliteal height This body dimension is needed to design seat height (distance between sitting area and surface). To achieve an optimum seat height, the fifth percentile should be used by designers (Keegan, 1962; Evans et al., 1988; Pheasant, 1991; Helander, 1997). It is well known that a seat that accommodates short-legged children will also accommodate long-legged children. Otherwise, a seat surface that causes the compression of the soft undersides of the thighs is designed. While designing seat height, allowances for shoes should be considered. Though researchers do not agree on one value (suggested values range from 20 mm to 45 mm), as Pheasant (1984) recommended, a value of 45 mm may put the designer on the right side. As to the seat surface, traditionally it was thought that a good chair is one with a horizontal surface. However, other studies show that when children are asked their preferences for seat surface, they preferred a seat with a forward inclination with the possibility to adjust the table top to a certain non-horizontal angle (Mandal, 1982). Fig. 2. Mean weight of boys and girls, age range 6–12 years.
3.2. Design of school furniture It noteworthy that school furniture design may be affected by many factors: educational, economic, cultural, and ergonomic. In this paper, ergonomic factors are considered. It is well known that the way of presenting the study results may or may not make these results applicable. For this reason, the results of this investigation are presented in percentiles for ease of use by designers. The body dimensions that are presented to designers are those that are relevant to the design of school furniture, mainly chairs and desks. Table 6 shows these dimensions (popliteal height, popliteal– buttock length, hip breadth, shoulder height, elbow height and
3.2.2. Popliteal–buttock length This body dimension is needed to design seat depth (distance between the front edge of seat to the back rest). To achieve an optimum seat depth, the fifth percentile is used (Keegan, 1962; Evans et al., 1988; Pheasant, 1991; Helander, 1997). If a seat is designed to properly accommodate short buttock–popliteal length, it will naturally accommodate children having long buttock– popliteal length. Otherwise, a seat surface either prevents children from making use of a back rest, or obliges them to sit with some of their lower leg on the seat surface causing a lot of stress on that area of leg. 3.2.3. Hip breadth This body dimension is needed to design seat width (distance between both sides of seat surface). To achieve an optimum seat
Table 5 Mean and standard deviation values of height (mm), and weight (kg) by age groups for (a) Boys, (b) Girls. References
Children’s nationality
Body measurements
Age (years) 6 Mean
a. Boys Gregory and Schwich (1977) Evans et al. (1988)
Bahraini Hong Kong
Prado-Leon et al. (2001) Diep (2003)
Mexican Vietnamese
Ozer (2007)
Turkish
This study (2007)
Bahraini
b. Girls Evans et al. (1988)
Hong Kong
Prado-Leon et al. (2001) Diep (2003)
Mexican Vietnamese
Ozer (2007)
Turkish
This study (2007)
Bahraini
7 SD
Height Weight Height Weight Height Weight Height Weight Height Weight Height Weight
1137 20.0 1175 22.8 1132 19.2 1206 24.93 1162 20.86
58 3.1 54 4 49 3.5 64 4.38 69 3.05
Height Weight Height Weight Height Weight Height Weight Height Weight
1118 18.7 1167 22.4 1115 18.1 1225 24.12 1183 24.61
28 1.3 54 4 46 2.5 80 4.19 59 6.60
Mean
8 SD
1177 21.3 1 228 25.8
48 2.7 57 5
1241 25.70 1233 24.56
56 4.89 68 4.84
1187 21.8 1218 25.1
70 4.2 54 5
1243 26.06 1188 22.00
67 6.21 60 4.75
Mean
9 SD
1220 22.8 1279 29.3 1216 21.4 1292 28.91 1266 25.70
57 2.7 46 6 48 3.3 70 6.34 70 4.00
1207 22.7 1269 28.4 1321 21.4 1273 26.43 1238 25.41
54 3.6 62 6 65 3.3 55 4.97 56 6.02
10
11
12
Mean
SD
Mean
SD
Mean
SD
Mean
SD
1263 24.53 1287 26.9 1334 32.8
51 31 62 4.9 61 7
66 52 71 9.1 68 9
1387 31.85 1456 38.0
70 57 98 9.2
66 7.5 101 6.0
62 42 91 8.0 67 9 57 4.4 77 8.13 75 6.87
1361 30.24 1413 35.4 1437 40.6
1345 32.24 1291 30.00
1324 28.19 1332 29.2 1381 36.3 1336 27.0 1385 35.15 1353 32.70
1400 36.24 1411 37.88
81 13.10 78 9.63
1499 43.14 1444 41.88
74 10.18 50 7.76
1280 26.7 1318 32.3
67 4.7 75 8
59 5.8 71 10
1479 38.0
56 7.7
64 6.70 50 5.58
51 4.1 67 8 71 5.9 78 10.13 80 10.38
1413 35.4 1457 42.3
1332 31.09 1272 25.60
1326 27.6 1399 36.3 1328 26.8 1413 38.10 1341 32.71
1481 41.38 1421 39.85
75 8.62 92 10.86
1527 45.04 1448 41.98
58 8.76 92 9.41
734
M. Mokdad, M. Al-Ansari / International Journal of Industrial Ergonomics 39 (2009) 728–735
Table 6 Percentiles. Measurement
Shoulder height (mm)
Knee height (mm)
Popliteal height (mm)
Elbow height (mm)
Buttock-popliteal length (mm)
Hip breadth (mm)
Percentiles
5 50 95 5 50 95 5 50 95 5 50 95 5 50 95 5 50 95
Boys
Girls
Age
Age
6
7
8
9
10
11
12
6
7
8
9
10
11
12
257 294 427 213 323 356 141 261 290 312 395 465 230 258 401 120 220 284
295 360 474 294 380 440 193 312 397 253 428 536 208 343 410 193 220 320
322 400 452 322 396 452 257 361 424 334 413 555 273 353 424 188 240 326
341 427 548 347 428 553 272 353 452 371 495 574 300 362 473 197 240 342
341 422 636 308 420 540 198 352 468 369 488 586 318 380 550 202 260 330
357 450 540 347 464 532 251 378 430 393 513 588 337 408 552 213 269 353
400 470 638 369 490 610 278 390 517 432 503 640 342 463 559 221 360 427
345 391 543 324 368 432 299 321 482 399 468 595 284 309 380 176 182 220
329 395 495 309 359 429 229 297 380 368 437 539 264 303 348 175 231 339
374 413 491 335 395 460 294 331 400 421 485 590 283 334 415 177 221 360
359 410 465 329 371 440 247 294 382 394 460 528 292 321 386 191 273 367
340 432 557 353 420 494 270 337 422 364 489 609 316 350 426 190 270 392
338 496 596 389 474 551 310 393 438 371 570 673 330 400 490 210 359 453
315 455 557 356 449 505 263 358 45 330 505 628 320 362 450 225 321 400
width, the 95th percentile is used (Keegan, 1962; Evans et al., 1988; Pheasant, 1991; Helander, 1997;). If a seat surface is designed to accommodate large hip breadth, it will also accommodate small hip-breadth children. Otherwise, the seat surface will compress the soft undersides of the hips. 3.2.4. Shoulder height This body dimension is needed to design seat backrest height (distance between seat surface and top of backrest). To achieve an optimum design, seat backrest height should be kept at 60–80% of shoulder height (Orborne, 1996; Gouvali and Boudolos, 2006) or be approximately 100 mm below shoulder height, so arm movements are not restricted (Pheasant, 1984). In any case, the level of the top of the backrest is determined by the fifth percentile. If seat backrest is designed at this level, it does not only accommodate the majority of school children, but it facilitates mobility of the trunk and arms as well. 3.2.5. Elbow height According to researchers, this body dimension is needed to design desk (table) top height and/or the arm rest (Dul and Weerdmeester, 1998; Milanese and Grimmer, 2004). To design an optimum desk top, desk top height should be 30–50 mm higher than elbow height (Pheasant, 1991) or be adjusted to elbow height (Parcells et al., 1999). In any case, the desk (table) top height is determined by the fifth percentile. If desk top is designed at this level, it does not only support the trunk of school children, but it helps them to efficiently carry out their school duties such as reading, writing, and drawing as well. 3.2.6. Knee height According to researchers, this body dimension is needed to design below-desk height (Dul and Weerdmeester, 1998; Sanders and McCormick, 1993; Helander, 1997). To achieve an optimum design, underneath desk height should be between 20 mm (Parcells et al., 1999) to 50 mm (Poulakakis and Marmaras, 1998) higher than knee height which is determined by the 95th percentile. If belowdesk height is designed at this level, it does not only allow free thighs and lower legs movement, but it allows for knee crossing as well. 3.2.7. Table depth and width Up to this moment, we have known how to design two parameters of school desk height (desk top and below-desk
heights) only. But what about other parameters such as table depth and width? In ergonomics, table depth and width designs are left to the functional requirements of work. If the amount of materials is large, then table depth and width should be large enough to accommodate all requirements. For the time being, at Bahraini schools, the amount of school work is still limited to the basic study skills (writing, reading, note-taking, drawing, etc.). Therefore, actual table depth and width are satisfactory. 4. Conclusion This paper aimed to anthropometrically describe Bahraini government school children aged between 6 and 12 years and to discuss how school furniture should be designed to cover anthropometric variability in children. As to the first aim, 44 anthropometric measurements were measured throwing light on the physique of the Bahraini children. As to the second aim, six anthropometric dimensions were measured, and percentiles and how to use them were given. Percentiles differed from one age to the other. Designers should take this variability into account to make furniture available that accommodates the majority of children. As Kolish (2003) noted, ‘‘ergonomic criteria while serving as the basis for furniture design, cannot be applied blindly for they do not guarantee comfortable seats’’. To ensure more comfortable seats, researchers have recommended various approaches, one of which is the provision of tables and chairs of different sizes in the same class, to accommodate anthropometric variability in children. As early as 1967, Oxford suggested that a range of six sizes of chairs and tables would accommodate children from kindergarten to secondary levels from the age of 4 to above 20 years of age (Oxford, 1969). More recently, Evans et al. (1988) suggested five sizes of chairs and tables, of which three sizes are for the elementary level: size one for small children, size two for medium children and size three for large children. A more objective size classification may be based on the following three criteria: body weight, chest circumference and hip breadth. These criteria seem to be a good indicator of body size. Another approach is adjustability. According to researchers (Evans et al., 1988; Parcells et al., 1999; Panagiotopoulou et al., 2004), the need for adjustable school furniture is becoming increasingly important. Researchers have been making every effort to make the workplace adjustable whenever possible considering
M. Mokdad, M. Al-Ansari / International Journal of Industrial Ergonomics 39 (2009) 728–735
other design requirements and constraints. Eastman Kodak Company Ergonomics Group (1986) suggested the following approach to workplace adjustment. First, the workplace is adjusted. If this is not feasible, then adjusting the worker position relative to the workplace, and adjusting the work piece. Finally, hand tools are adjusted. In this context, Jung designed adjustable school furniture to fit as many Korean school children as possible. He mentioned that children who used the newly designed furniture expressed a lot of subjective comfort (Jung, 2005). Acknowledgments This study has been undertaken at Bahrain University, and sponsored by the deanship of scientific research. The authors wish to thank the Bahrain University authorities and the National Education Ministry for their collaboration. The authors would like to thank the school principals and children involved in the study for their patient and friendly cooperation. The authors would also like to thank all the data collectors for their contribution during the data collection process. Finally, the authors thank all those who participated in the preparation of the manuscript for their constructive comments. References: Ali, M.A., Uetake, T., Ohtsuki, F., 2000. Secular changes in relative leg length in postwar Japan. American Journal of Human Biology 12 (3), 405–416. Anxionnat, R., Berger, M.O., Kerrien, E., Bracard, S., Picard, L., 2003. Intra- and interobserver variability in the angiographic delineation of brain arterio-venous malformations. International Congress Series 1256, 1297. Bakwin, H., McLaughlin, S.D., 1964. Secular increases in height. Is the end in sight? Lancet 2, 1195–1196. Carrascosa, A., Yeste, D., Copil, A., Gussinye, M., 2004. Secular growth changes. Weight, height and body mass index values in infant, children, adolescent and young adults from Barcelona population. Medical Clinics (Barcelona) 123 (12), 445–451. Damon, A., 1968. Secular trend in height and weight within Old American families at Harvard, 1870-1965. American Journal of Physical Anthropology 29, 45–50. Diep, N.B., 2003. Evaluation of fitness between school furniture and children body size in two primary schools in Haiphong, Vietnam. Master’s thesis, Department of Human Work Science, Division of Industrial ergonomics, Lulea University of Technology, Sweden. Directorate of Statistics, 2006. Bahrain in Figures. General Directorate of Statistics, and Population Registry, Central Informatics Organisation, Kingdom of Bahrain. Dul, J., Weerdmeester, B., 1998. Posture and movement. In: Dul, J., Weerdmeester, B. (Eds.), Ergonomics for Beginners. A Reference Guide. Taylor and Francis, London, pp. 11–18. Eastman Kodak Company Ergonomics Group, 1986. Ergonomics Design for People at Work, Vol. 1. Van Nostrand Reinhold, New York. Evans, W.A., Courtney, A.J., Fok, K.F., 1988. The design of school furniture for Hong Kong schoolchildren. Applied Ergonomics 19 (2), 122–134. Freudentjal, A., Riel, M., Molenbriek, J., Sniders, C., 1991. The effect on sitting posture of a desk with a ten-degree inclination using an adjustable chair and table. Applied Ergonomics 22 (5), 329–336. Frisancho, A.R., 1993. Anthropometric Standards for the Assessment of Growth and Nutritional Status. The University of Michigan Press, Ann Arbor. Gillum, R.F., 1987. The association of the ratio of waist to hip girth with blood pressure, serum cholesterol and serum uric acid in children and youths aged 6– 17 years. Journal of Chronic Diseases 40 (5), 413–420. Ghoddousi, H., Edler, R., Haers, P., Wertheim, D., Greenhill, D., 2007. Comparison of three methods of facial measurement. International Journal of Oral and Maxillofacial Surgery 36, 250–258. Gouvali, M.K., Boudolos, K., 2006. Match between school furniture dimensions and children’s anthropometry. Applied Ergonomics 37, 765–773. Gregory, W.B., Schwich, L.C., 1977. Bahrain Fitness Testing Manual. Bahrain Sports Institute. General Organization for Youth and Sports. Bahrain.
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