Contents lists available at ScienceDirect International Journal of Industrial Ergonomics journal homepage: www.elsevier.com/locate/ergon On-body personal assist suit for commercial farming: Effect on heart rate, EMG, trunk movements, and user acceptance during digging Nugrahaning Sani Dewi a , Masakazu Komatsuzaki a,b,* a United Graduate School of Agricultural Science, Tokyo University of Agriculture and Technology, Saiwaicho 3-5-8, Fuchu, Tokyo, 183-8509, Japan b Center for International Field Agriculture Research & Education, Ibaraki University, 3-21-1, Ami, Inashiki, Ibaraki, 300-0393, Japan ARTICLE INFO Keywords: On-body personal assist suit Digging task sEMG ABSTRACT Personal “protective” equipment has been recommended in agricultural tasks. The plastic mulching process is often required in commercial farming. On-body personal assist suits (PAS) affect heart rate, muscles, trunk movement, and user acceptance. In this study, 8 male and 6 female subjects performing 3-min digging tasks were evaluated. Electrocardiograph, electromyography of the right and left upper trapezius and (L3) lumbar erector spinae, and motion data were simultaneously recorded using a multichannel telemetry system. In the task's final minute, the workload was decreased using PAS in males, although the average workload did not change. Males achieved a more stable acceleration pattern using PAS as compared to females. 86% females experienced dis- comfort in the crotch area; therefore, we recommend that hip straps be modified to increase user acceptance. For a typical agricultural forward-bending task, such as digging, PAS can significantly reduce strain (p < 0.05) on lower back muscles (L3). 1. Introduction Workers in the agricultural sector, in general, especially in labor- intensive agriculture, are at high risk of musculoskeletal disorders (Palmer; 1996; Meyers et al. 2000; Jin et al. 2009; Fathallah, 2010; Kirkhorn et al. 2010; Keawduangdee et al. 2015; Thetkathuek et al., 2018). Although farm machinery and mechanization have greatly di- minished the manual labor required for field preparation, the use of such equipment is not fully mechanized. Manual tasks such as digging often require in the plastic mulching process in commercial farming. Digging involves repetitive forward flexion, and is targeted as a priority task for health intervention. On-body ergonomic aid devices such as personal lift-assist devices (PLADs) and personal weight-transfer devices have been shown to re- duce lower back muscular activity during lifting (Abdoli-e et al., 2006; Abdoli-e and Stevenson, 2008; Lotz et al. 2009; Godwin et al. 2009; Ulrey and Fathallah, 2013) and the static forward bending that is executed by workers in the automotive industry (Graham et al. 2009). PLADs use elastic bands in a passive system mounted on the upper back to transfer force and moment from the spinal column to the shoulders, pelvic girdle, and knees (Lotz et al. 2009). Another option is the on- body personal assist suit (PAS), which has recently become commer- cially available. Similar to the PLAD, a PAS has an elastic system for the upper back. PAS weighs only 1.04 pound which is lighter than PLAD and similar to a normal suit. Such on-body ergonomic aid devices are often evaluated in simulated laboratory or industrial settings but have yet to be evaluated in the field for agricultural tasks. A few studies have investigated trunk movement while performing manual handling in industrial farming. Graham et al. 2009 has investigated trunk inclina- tion using an accelerometer during static forward bending in the au- tomotive industry. Thus, the aim of the present study is to evaluate how PAS affect the heart rate, muscles, and trunk movement and whether users accept to wear them while digging for a period of 3 min, which is a repetitive dynamic forward bending task commonly encountered in agriculture. In previous works (Godwin at al. 2009; Lotz et al., 2009), the effect of PLAD was found to be statistically similar for women and for men. However, men and women have different trunk motion and knee-angle ranges, which need to be considered separately when evaluating work technique in manual-handling tasks (Lindbeck and Kjellberg, 2001). Thus, the present study monitors how PASs affect both male and female subjects and also records the acceleration pattern. PASs could prove to be a simple safety intervention in field-related applications. The hy- pothesis of this study is that wearing a PAS reduces the demand on back muscles during digging. https://doi.org/10.1016/j.ergon.2018.08.013 Received 22 May 2018; Received in revised form 24 July 2018; Accepted 27 August 2018 * Corresponding author. Center for International Field Agriculture Research & Education, Ibaraki University, 3-21-1, Ami, Inashiki, Ibaraki, 300-0393, Japan. E-mail addresses: nugrahaningsani@gmail.com (N.S. Dewi), masakazu.komatsuzaki.fsc@vc.ibaraki.ac.jp (M. Komatsuzaki). International Journal of Industrial Ergonomics 68 (2018) 290–296 0169-8141/ © 2018 Elsevier B.V. All rights reserved. T