Objective: This study aimed at evaluating the acute effect of the combined and single use of two orthotic devices (neck balance system [NBS] and lumbar sup- port [LS]) on muscle activity of neck and back muscles during typical computer working tasks. Background: An excessive activation of neck mus- cles could threaten the balance between agonist and antagonist muscles, resulting in a lower stability of the head and possibly leading to neck pain. At present, no study evaluated the effect of a specific orthotic device in reducing neck muscles activation. Methods: Surface electromyography (sEMG) from neck flexor (sternocleidomastoid [SCMD]) and extensor muscles (semispinalis capitis [SPC]) and back extensor muscles (erector spinae [ERS]) of 20 healthy individuals was recorded during three computer work- ing tasks performed with the NBS, with NBS and LS, with the LS, and without devices (ND). Results: In the NBS condition, the SPC showed a reduced activation (NBS = 3.97%; NBS + LS = 4.49%; LS = 4.48%; ND = 4.61% of the maximal voluntary con- traction) compared to the other conditions. Conclusions: The use of the NBS promotes a reduction of neck extensor muscles, possibly due to the inertial mass added in the occipital part of the head, producing an external neck extensor moment that cooperates with that produced by neck extensor muscles. Application: Orthotic devices such as the NBS may be used by computer workers to reduce the acti- vation of their neck extensor muscles and possible risks of developing neck pain. Keywords: sEMG, neck balance system, orthotic devices, neck muscles INTRODUCTION Neck pain is a common medical condition that represents a major public health concern in terms of personal health, overall well-being (Cote, Cassidy, & Carroll, 2001; Fejer, Kyvik, & Hartvigsen, 2006), and medical costs (Bas- sols, Bosch, & Banos, 2002; Borghouts, Koes, Vondeling, & Bouter, 1999). In Europe and North America, one-third of adults experience neck pain in the course of one year (Bovim, Schrader, & Sand, 1994; Cote et al., 1998; Croft et al., 2001). A large number of researchers pointed out that prolonged sedentary work in computer workers and office administrators is one of the major risk factors to developing neck pain (Brandt et al., 2004; Dong, 2005; Eriksen, Natvig, Knardahl, & Bruusgaard, 1999; Korho- nen et al., 2003). Sedentary work potentially leads to changes in body posture such as for- ward head posture (Bokaee et al., 2016), which is characterized by greater flexion of the lower cervical spine, greater extension of the upper cervical spine, and higher scapular protraction and elevation than those commonly observed in a correct posture (Szeto, Straker, & Raine, 2002). This posture, assumed for a prolonged time, induces a creep response in the tissues (Harms-Ringdahl, Ekholm, Schuldt, Nemeth, & Arborelius, 1986; Twomey & Taylor, 1982) and increases compressive loading in the cer- vical spine as well as neck muscle activation (Schuldt, Ekholm, Harms-Ringdahl, Nemeth, & Arborelius, 1986). It has been shown that patients with neck pain experience higher acti- vation of neck flexor (Lindstrom, Schomacher, Farina, Rechter, & Falla, 2011; Zito, Jull, & Story, 2006) and neck extensor (Johnston, Jull, Souvlis, & Jimmieson, 2008; Lindstrom et al., 2011; Szeto, Straker, & O’Sullivan, 2005) mus- cles. An excessive activation of neck muscles could threaten the balance between agonist and 814957HFS XX X 10.1177/0018720818814957Human FactorsNeck Balance System in Sedentary Workersresearch-article 2019 Address correspondence to Federico Quinzi, Santa Lucia Foundation IRCCS, Via ardeatina 306, Rome, 00179, Italy; e-mail: fquinzi@libero.it. The Effect of an Orthotic Device for Balancing Neck Muscles During Daily Office Tasks Federico Quinzi, Santa Lucia Foundation IRCCS, Rome, Italy, Martina Scalia, Arrigo Giombini, Alessandra Di Cagno, Fabio Pigozzi, University of Rome “Foro Italico,” Italy, Maurizio Casasco, Italian Sports Medicine Federation, Rome, Italy, and Andrea Macaluso, University of Rome “Foro Italico,” Italy HUMAN FACTORS Vol. XX, No. X, Month XXXX, pp. 1–14 DOI: 10.1177/0018720818814957 Article reuse guidelines: sagepub.com/journals-permissions Copyright © 2019, Human Factors and Ergonomics Society.