Galley Proof 25/11/2019; 14:24 File: bmr–1-bmr191500.tex; BOKCTP/xjm p. 1 Journal of Back and Musculoskeletal Rehabilitation -1 (2019) 1–6 1 DOI 10.3233/BMR-191500 IOS Press Electromyographic activity of the neck muscles: Effects of varying standing height-derived teaching board heights Chidiebele Petronilla Ojukwu a , Chioma Nneka Ikele a , Onyekachi Darlington Nwobodo a , Adaora Justina Okemuo a , Ikenna Theophilus Ikele b,∗ , Chigozie Ikenna Uchenwoke a and Uchechukwu Anthonia Ezeugwu a a Department of Medical Rehabilitation, Faculty of Health Sciences and Technology, University of Nigeria, Nigeria b Department of Anatomy, Faculty of Basic Medical Sciences, University of Nigeria, Nigeria Abstract. BACKGROUND: Despite the increasing emergence of modern facilities, the ancient practice of writing on a teaching board is still common in the teaching profession. Ergonomic guidelines of this practice are required for the prevention of work-related neck musculoskeletal disorders inherent of teachers. OBJECTIVE: This study investigated the effects of varying teaching board heights on the activities of the neck muscles. METHODS: Thirty participants (15 males and 15 females) participated in this experimental study. Each performed writing tasks on a teaching board set at five different heights derived from their standing height (SH) [(D 10 = SH minus 10% of SH; Norm H = SH; Sum 10 = SH plus 10% of SH; Sum 20 = SH plus 20% of SH; Sum 25 = SH plus 25% of SH)]. Electromyographic (EMG) activities of both components of the sternocleidomastoid and upper trapezius muscles were measured during each task. Asymmetry ratio of right and left muscle components were determined. Data were analyzed with one-way ANOVA. RESULTS: EMG activities of the four muscles as well as their asymmetry ratios significantly (p< 0.01) increased with increas- ing board heights. CONCLUSION: Teaching board-related tasks have increased possibilities of inducing neck disorders when performed beyond Norm H vertical heights. Keywords: Teaching board height, neck muscles, electromyography 1. Introduction 1 The teaching profession is characterized by de- 2 mands for professional knowledge, instructional ef- 3 fectiveness, good communication, critical thinking, in- 4 terpersonal skills, integration of discipline, technol- 5 ogy integration, organization and classroom manage- 6 ment [1]. These demands are associated with increased 7 mental and physical tasks, predisposing teachers to ad- 8 verse mental and physical health issues [2]. It was re- 9 * Corresponding author: Ikenna Theophilus Ikele, Department of Anatomy, Faculty of Basic Medical Sciences, University of Nigeria, Nigeria. Tel.: +234 8033438709; E-mail: ikenna.ikele@gmail.com. ported that about 40–50% of teachers leave the pro- 10 fession within the first five years of their occupa- 11 tion, attributable to interacting physical, environmen- 12 tal and psychosocial factors [3]. Physical health prob- 13 lems, particularly musculoskeletal disorders are preva- 14 lent among school teachers [2,4–8]. The most com- 15 mon teaching-related musculoskeletal disorders in- 16 clude shoulder [5,8,9], neck [2,8,10–12] and low back 17 disorders [13]. Among several factors associated with 18 teaching-related musculoskeletal disorders, overhead 19 writing tasks on high teaching boards have been im- 20 plicated as one of the predisposing factors of neck and 21 shoulder musculoskeletal disorders in teachers [7,8,11, 22 14], teaching board height correlated with the inci- 23 ISSN 1053-8127/19/$35.00 c  2019 – IOS Press and the authors. All rights reserved corrected proof version