Anthropometric measures of young Nigerians for ergonomic furniture design

Background: Ergonomic furniture design which is based on the application of the anthropometric measurements of the intended users does not only reduce the risk of developing musculoskeletal disorders such as low back pain, but also improves work performance. Aim: The main aim of this study was to survey and describe Nigerian University students based on important anthropometric measures relevant to ergonomic classroom furniture design. Method: A total of fi ve hundred and ninety (undergraduate and graduate) students where surveyed using the traditional methods of data capture. The measurement considered were the most important anthropometric features relevant to ergonomic furniture design. Result: The result of the survey was stratifi ed according to gender and age. Across all age groups, males had higher mean values for anthropometric measurement except for the hip width which was found to be higher in females than in males. When the participants were considered broadly as just males and females without consideration for their age groups, sexual dimorphism was seen to still exist. The males had higher mean values for all the anthropometric measurement except for hip width (males = 30.7±2.7cm; females = 33.9±3.7cm). Dimensions for ergonomic furniture design for the study population was also determined and presented. Conclusion: The study anthropometrically describes young Nigerians and therefore provides data which can be deployed by furniture designers for ergonomic product manufacture. Research Article Anthropometric measures of young Nigerians for ergonomic furniture design Fidelis OP1*, Ogunlade B2 and Adelakun SA2 1Department of Biomedical Technology, Federal University of Technology, Akure, Nigeria 2Department of Anatomy, Federal University of Technology, Akure, Nigeria Received: 06 June, 2019 Accepted: 19 September, 2019 Published: 20 September, 2019 *Corresponding author: Fidelis OP, Department of Biomedical Technology, Federal University of Technology, PMB 704, Akure, Nigeria, Tel: +234-80381-937-99; E-mail:


Introduction
The science of ergonomics is aimed at fi tting work and environment to the end user such that the ease of use, safety and effectiveness of the user is improved [1]. Anthropometry, one of the oldest tools of ergonomics, is defi ned as the science which deals with body shapes, sizes, strength and working capacity [2], for the purpose of design [3]. Anthropometric measurements when considered in design, improves usability, creates feeling of comfort and reduces the risk of developing musculoskeletal disorders arising from the use of such designs [4][5][6]. Sitting is an important part of human daily activity and the use of ill-fi tted furniture can mar this experience as well as diminish performance and productivity in those activities that may be carried out in a sitting position [7,8]. Mismatch between students' anthropometric measures and furniture dimensions can affect classroom activities such as writing, reading and typing; causing pain in the back, shoulders, neck, legs and eyes [9][10][11]. It is for these reasons that classroom furniture should be designed using anthropometric data of the intended users [12]. The need for ergonomic classroom furniture is not only applicable to children alone but in a University environment as well, because repetitive strain injuries which may occur from poor sitting postures not only affect primary school children and teenagers but are also noticeable in college students [13]. Ergonomic designs which suit users and reduce discomfort resulting from use rely on a number of tools one of which is the anthropometric measures of the end-user [1]. Sadly, there is a dearth of information on the ergonomic suitability of educational furniture for students, especially in the higher institutions of learning in Nigeria [14], resulting in a large number of mismatch between anthropometric measures of users and furniture dimensions [15]. The design of DOI: https://dx.doi.org/10.17352/jbm.000017 classroom furniture for Nigerian schools with anthropometric measurements obtained from other parts of the world is unacceptable because body composition, size and shape have been reported to differ across races and nations [16].
Therefore, this study aims to survey and anthropometrically describe a student's population in a Nigerian University using measures relevant to ergonomic furniture design.

Instruments
Several researchers have reported the existence of 3-D body scanners for making anthropometric measurements; they also report the relative unavailability of such scanners [1,17]. As a result, researchers use the traditional methods for obtaining data. According to studies [11,18], anthropometric data obtained with the use of the traditional methods have been shown to be accurate and reliable as those obtained using some hi-tech equipment. Traditional methods have also been used for similar studies in Nigeria [14,15,19]. An anthropometer was

Data collection
The study was conducted within the Federal University of Technology, Akure, Nigeria. A total of 590 (295 males and 295 females) students were selected by simple random sampling. The purpose of the study was clearly explained to the participants and an informed consent was obtained from each participant. They were all told to present themselves for the measurements in light clothing. The anthropometric dimensions of the students were taken from the right side of each person, while they were sitting in an erect position on a height-adjustable chair with a horizontal surface and had no shoes on them. The knees and elbows were fl exed at 90 o during the measurements.

Body dimensions
Several researchers have reported that certain anthropometric dimensions are to be considered in ergonomic furniture design. These include popliteal height, buttockpopliteal length, hip width, shoulder height, elbow rest height, thigh thickness and knee height [1,13,20,21]. In addition to these, the present study included stature, body weight and shoulder breadth. The anthropometric dimensions are as defi ned by ISO 7250 (1996) and reported by [17,22].

Results
The anthropometric measures of the participants in this study are shown in Table 1. The result is presented for males and females as well as for the different age stratifi cation in the study. The combined result of all participants (males and females) in the study is shown in Table 2. The result also includes the 5 th , 50 th and 95 th percentile values of all the measures. The anthropometric measures of all males in the study was also analysed and is presented in Table 3. In addition, the anthropometric measures of all females in the study was also analysed and is as presented in Table 4. The differences in the mean values of the anthropometric measures of the male and female participants in the study are shown in a chart in Figure 1.

Sexual dimorphism in anthropometric measures in young nigerian adults
The results of the study show sexual dimorphism of anthropometric measures. As shown in Table 1

Comparison with similar studies
Similar studies have been conducted in Nigeria [14,19] and outside Nigeria [11]. The former study surveyed the anthropometric measures of students at the University of Ibadan, Nigeria [14] and at a publics University in Iran [11] and compared the features with the dimensions of classroom furniture and Library furniture respectively, within the Universities. A third study [19],  All dimensions are in centimetres (cm) except body weight which is recorded in kilograms (kg).
from [19], are compared with those obtained from the present study in Table 5. The result from [14], was not presented in the form shown in Table 5; however, sexual dimorphism in the anthropometric measures of male and female participants was obvious in the result as presented. The males had higher mean values for all the measures.
A graphical comparison of the mean values for anthropometric measures in the present study with those from previous studies [11,19], is shown in Figure 2.  Table 2. The ideal furniture dimensions for the study population were calculated and the results are presented in

Discussion
Ergonomic furniture design requires the utmost consideration of the anthropometric measures of the end users.
This study therefore presents the relevant anthropometric measurements required for the design of ergonomic classroom furniture for University students.
The applications of these results to ergonomic furniture design are as follows:

Popliteal height: This body dimension is usually used
for the design of the seat height and is expected to be higher that the height of the seat [23][24][25]. The seat   All dimensions are in centimetres (cm) except body weight which is measured in kilograms (kg).

Thigh thickness:
The thigh thickness is used to design the seat-desk clearance, SDC, (the distance between the seating surface and the under-surface of the desk/table).
The seat-desk clearance is considered appropriate when it is higher than the thigh thickness leaving enough room to permit leg movement. The SDC is designated for the ninety-fi fth percentile of the thigh thickness.

Hip width:
Is used for the design of seat width. The ninety-fi fth percentile of the hip width is used for optimum seat width design. A seat width that accommodates the largest hip breadth will also accommodate the smaller hip breadth.

Shoulder height:
This body dimension is used to design the backrest height of the seat. For optimum backrest benefi t, the fi fth percentile of the shoulder height is designated for the backrest height design.

Knee height:
The knee height is alternatively used to design the under-desk height. The optimum underdesk height is estimated to be between 20mm-50mm higher than the knee height [25] and designated for ninety-fi fth percentile of the knee height.

Elbow height:
The elbow height is used to determine appropriate seat-desk height and/or arm rest height because when arms can be supported, there is a reduction in the load on the spine [24]. The desk/table surface height is designated for the fi fth percentile of the elbow height.
The designed classroom furniture for the study population (dimensions in Table 6) is expected to create comfort and reduce the risk of musculoskeletal disorder in persons who use such furniture. This is a major signifi cance of a study like this. The use of furniture designed without appropriate anthropometric consideration has severe health implications. According to [25], when seating surfaces are too high, it causes discomfort and impaired blood circulation around the thighs. The user often has to move forward on the seat as a compensatory measure, thus, assuming a kyphotic posture due to lack of back support. When a seat is too low, the weight of the user is transferred to a small area of the ischial tuberosities resulting in an uneven distribution of pressure over the posterior thigh.
Seats that are too deep for a user usually result in reduced blood fl ow to the legs and feet because the front edge of the seat presses against the back of the knee. The use of poorly designed classroom furniture will require greater muscular force and control to maintain stability and equilibrium [25] and often results in discomfort (in the form of irritation) as well as pain on the back and neck and even an alteration in the normal posture of the individual. On the other hand, maintaining an upright sitting posture is beneficial to the back muscles [4], just as much as well-fi tting classroom furniture will improve classroom comfort and facilitate learning.

Conclusion
In conclusion, this study provides classroom furniture designers and importers with a baseline description of the anthropometric dimensions of young Nigerians. More of this kind of study is recommended for a number of reasons; to anthropometrically describe young Nigerian adults at any given era and to provide anthropometric data for ergonomic furniture designs.   [11,19]. All dimensions are in centimetres (cm) except body weight which is recorded in kilograms (kg). DOI: https://dx.doi.org/10.17352/jbm.000017 Table 5: Comparison between the results from the present study with the results from previous studies [11,19]. All dimensions are in centimetres (cm) except body weight (BW) which is measured in kilograms (kg). All dimensions are in centimetres (cm).