Background: Malaysian primary schoolchildren spend five to six hours seated daily, yet classroom furniture is still commonly selected without child-specific ergonomic criteria. This creates an important pediatric healthcare concern because prolonged sitting, anthropometric mismatch, and maladaptive postures may contribute to musculoskeletal discomfort, poor spinal alignment, and early musculoskeletal risk. In the present setting, two-thirds of students carried school bags heavier than 4 kg, while more than half reported combined bending and slouching postures.

Objective: This study aimed to identify the most problematic sitting posture among primary school students in Selangor, determine which chair design is most strongly associated with poor posture, and examine the relationship between chair variants and back-body discomfort using observational and physiological assessment.

Methods: A field-based case study was conducted among 30 students aged 7–12 years from three schools in Banting, Selangor. Three chair variants were evaluated: wooden, plastic, and mixed-material (plastic-metal). Perceived discomfort at the neck, upper back, middle back, lower back, and both shoulders was assessed. Postural risk was evaluated using Rapid Upper Limb Assessment (RULA), and trapezius and longissimus muscle activity was measured using surface electromyography (EMG) during static and dynamic sitting.

Results: The mixed-material chair showed the highest comfort score (4.26±0.60), followed by plastic (3.85±0.47) and wooden chairs (3.29±0.59). However, none achieved an acceptable RULA score, and the wooden chair showed the greatest ergonomic risk, with 63.3% scoring 7. EMG findings showed that bending produced the highest muscle activation, particularly in the left trapezius, while the wooden chair generated the highest RMS during dynamic activity.

Conclusion: Postural risk in Malaysian schoolchildren is influenced by both chair design and sustained bending behavior, highlighting the need for ergonomic furniture, anthropometry-based procurement, posture education, and movement breaks. The study’s novelty lies in integrating discomfort ratings, RULA, and EMG within one Malaysian primary-school ergonomic framework.

Irwan Syah Md Yusoff is an Associate Professor at the Department of Resource Management and Consumer Studies, Faculty of Human Ecology, Universiti Putra Malaysia. He holds a PhD in Human Factors and Ergonomics from Universiti Sains Malaysia, a Master’s degree in Occupational Safety and Health (Ergonomics), and a Bachelor’s degree in Industrial Design from Universiti Putra Malaysia. His research centers on ergonomics, sustainable consumer product design, user-centred innovation, and health-related design evaluation, with a strong focus on musculoskeletal risk, product safety, and human well-being. He has published extensively in reputable journals and conference proceedings, with 191 Scopus citations (h-index 6) and 359 Google Scholar citations (h-index 8). In addition to his scholarly output, he serves as a guest professor at Jinan Engineering Polytechnic, China, and holds leadership and editorial roles in the Human Factors and Ergonomics Society Malaysia and several consumer research journals. He led and supervised numerous undergraduate, master’s, and doctoral research projects, reflecting his strong commitment to research mentorship and academic excellence. His sustained contributions to teaching, innovation, and applied research have been recognized through multiple Excellent Service awards and national and international recognitions, positioning him as a credible and impactful researcher in ergonomics and design.