Full Terms & Conditions of access and use can be found at https://www.tandfonline.com/action/journalInformation?journalCode=tose20 International Journal of Occupational Safety and Ergonomics ISSN: 1080-3548 (Print) 2376-9130 (Online) Journal homepage: https://www.tandfonline.com/loi/tose20 The influence of axle position and the use of accessories on the activity of upper limb muscles during manual wheelchair propulsion Guilherme da Silva Bertolaccini, Idinei Francisco Pires de Carvalho Filho, Gustavo Christofoletti, Luis Carlos Paschoarelli & Fausto Orsi Medola To cite this article: Guilherme da Silva Bertolaccini, Idinei Francisco Pires de Carvalho Filho, Gustavo Christofoletti, Luis Carlos Paschoarelli & Fausto Orsi Medola (2018) The influence of axle position and the use of accessories on the activity of upper limb muscles during manual wheelchair propulsion, International Journal of Occupational Safety and Ergonomics, 24:2, 311-315, DOI: 10.1080/10803548.2017.1294369 To link to this article: https://doi.org/10.1080/10803548.2017.1294369 Accepted author version posted online: 17 Feb 2017. Published online: 24 Mar 2017. Submit your article to this journal Article views: 170 View Crossmark data Citing articles: 3 View citing articles https://www.tandfonline.com/action/journalInformation?journalCode=tose20 https://www.tandfonline.com/loi/tose20 https://www.tandfonline.com/action/showCitFormats?doi=10.1080/10803548.2017.1294369 https://doi.org/10.1080/10803548.2017.1294369 https://www.tandfonline.com/action/authorSubmission?journalCode=tose20&show=instructions https://www.tandfonline.com/action/authorSubmission?journalCode=tose20&show=instructions http://crossmark.crossref.org/dialog/?doi=10.1080/10803548.2017.1294369&domain=pdf&date_stamp=2017-02-17 http://crossmark.crossref.org/dialog/?doi=10.1080/10803548.2017.1294369&domain=pdf&date_stamp=2017-02-17 https://www.tandfonline.com/doi/citedby/10.1080/10803548.2017.1294369#tabModule https://www.tandfonline.com/doi/citedby/10.1080/10803548.2017.1294369#tabModule International Journal of Occupational Safety and Ergonomics (JOSE), 2018 Vol. 24, No. 2, 311–315, https://doi.org/10.1080/10803548.2017.1294369 The influence of axle position and the use of accessories on the activity of upper limb muscles during manual wheelchair propulsion Guilherme da Silva Bertolaccinia, Idinei Francisco Pires de Carvalho Filhob, Gustavo Christofolettic, Luis Carlos Paschoarellia,b and Fausto Orsi Medola a,b∗ aGraduate Programme in Design, UNESP – University Estadual Paulista, Brazil; bDepartment of Design, UNESP – University Estadual Paulista, Brazil; cDepartment of Physiotherapy, UFMS – Federal University of Mato Grosso do Sul, Brazil Introduction. Wheelchair configuration is an important factor influencing the ergonomics of the user–device interface and, from a biomechanical point of view, small changes in chair setup may have a positive influence on the demand on the upper limbs during manual propulsion. This study aimed to investigate the influence of the position of the rear wheels’ axle and the use of accessories on the activity of upper limb muscles during manual wheelchair propulsion. Methods. Electromyography signals of the biceps, triceps, anterior deltoids and pectoralis major were collected for 11 able-bodied subjects in a wheelchair propulsion protocol with four different wheelchair configurations (differing in axle position and the use of accessories) on a straightforward sprint and a slalom course. Results. With accessories, moving the axle forward led to a decrease in the activity of all muscles in both the straightforward sprint (significant differences in triceps, anterior deltoids and biceps) and the slalom course (significant difference in anterior deltoids and biceps). However, when propelling the chair without accessories, no difference was found related to axle position. Conclusion. Changes in wheelchair configuration can influence the ergonomics of manual wheelchair propulsion. Reducing the biomechanical loads may benefit users’ mobility, independence and social participation. Keywords: wheelchairs; biomechanics; manual propulsion; ergonomics; assistive technologies 1. Introduction Wheelchair use has been addressed in a variety of top- ics covering the biomechanics of manual propulsion [1–3], sports [4,5], problems related to mobility [6,7] and work- place [8–10]. Although used widely, the wheelchair has problems that prevent the user from moving with indepen- dence, safety and satisfaction. From an ergonomic point of view, such problems can be divided into two main top- ics: seating and mobility. While the former focuses on the interaction between the user’s body and the support inter- faces (seat, backrest, armrest and foot support), mobility addresses the user’s actions and the resulting movement of the wheelchair. Manual wheelchairs users have many functional diffi- culties in daily life. Mobility tasks as simple as climbing a sidewalk can be very hard. In this way, moving with the wheelchair for long distances is strongly limited and, as a result, the daily distance traveled and average speed are significantly lower in wheelchair mobility when com- pared with walking [11–14]. Manual wheelchair propul- sion exposes the upper limbs to a harmful combination of load and repetition that may cause many injuries [15]. Because users occupy the chair for about 11 h/day [14], the wheelchair becomes an extension of the users’ body *Corresponding author. Email: fausto.medola@faac.unesp.br and influences their social participation [16] and daily work. In order to study wheelchair mobility in a closer way to how people move in their daily routine, it is impor- tant to investigate the biomechanics of manual propulsion not only in straightforward motion, but also in trajectories comprising changes in movement direction and accelera- tion. A previous study demonstrated that the influence of the mechanical aspects on the movement of the wheelchair is dependent on the trajectory and acceleration [17]. The wheelchair configuration is very important to determine the upper limb actions during manual propul- sion. The position and camber of the rear wheels, tire and wheel types, seat and backrest angles, frame design and the use of accessories (armrest, clothing shields) are features of the equipment design that can affect propulsion forces, upper limb range of motion, rolling resistance and sys- tem stability [18]. Therefore, a proper selection regarding the wheelchair configuration can improve overall mobility performance. Many wheelchairs have adjustable settings allowing the users to set up the wheelchair in accordance with their needs and preferences. Moving the rear wheels forward or rearward and using or removing accessories such as © 2017 Central Institute for Labour Protection – National Research Institute (CIOP-PIB) http://crossmark.crossref.org/dialog/?doi=10.1080/10803548.2017.1294369&domain=pdf http://orcid.org/0000-0003-2308-6524 mailto:fausto.medola@faac.unesp.br 312 G. da Silva Bertolaccini et al. armrests and seat cover plates are two changes in config- uration commonly made by users to make the equipment more suitable to them. However, the influence of the com- bination between axle position and use of accessories on the biomechanics of manual propulsion is still unclear. This information may contribute to improve the ergonomics of manual wheelchairs by providing objective data on how changes in the equipment configuration influence the users’ actions during manual wheelchair propulsion. This study aimed at investigating the influence of the position of the rear wheels’ axle and the use of acces- sories on the activity of upper limb muscles during manual wheelchair propulsion. Figure 1. Relative position of the rear wheels to the user. 2. Materials and methods 2.1. Participants A convenience sample of 11 participants without physi- cal disabilities (mean age 23.82 ± 3.46 years, mean height 1.77 ± 0.06 m, mean weight 76.09 ± 11.43 kg), all male, were recruited at the São Paulo State University (UNESP, Bauru, Brazil) and voluntarily participated in this study. Participants met the following inclusion criteria: (a) mini- mum age of 18 years; (b) had no upper limb pain, injuries or disorders that could influence the manual wheelchair propulsion. Prior to data collection, participants read and signed an informed consent form that had been submitted and approved by the Ethics Committee of the Faculty of Architecture, Arts and Communication – UNESP (Process. N. 800.500). 2.2. Equipment and procedure A manual wheelchair with a rigid frame was used in four different configurations, varying according to a relative fore–aft rear axle position to the frame of 50 mm (Figure 1) and the use or not of accessories (clothing shields and armrests), as shown in Figure 2. The total weight of the accessories was 1.95 kg. These configurations were tested in two different tra- jectories: straightforward sprint (acceleration in a 15-m straight motion) and slalom course (nine cones aligned and separated by decreasing distances) (Figure 3), as proposed in a previous study [17]. For both trajectories, subjects were instructed to propel the chair as fast as possible. The sequence of trajectories and wheelchair configurations were randomized for each subject. During the tests, surface electromyography (EMG) data of the biceps brachial, triceps brachial, anterior deltoids and pectoralis major were collected using four-channel wireless sensors (T-Sens; TEA Ergo, France) and a Data- logger module (CAPTIV; TEA Ergo, France) to register the EMG signals. Triode surface self-adhesive electrodes T3402M (Thought Technology, Canada) were placed in the Figure 2. Wheelchairs with and without accessories. International Journal of Occupational Safety and Ergonomics (JOSE) 313 Figure 3. Slalom course. Table 1. Mean EMG activity (mV) of the four muscles during manual wheelchair propulsion with the accessories. Muscle Trajectory Rearward axle Forward axle p Pectoralis major Straightforward 101.64 (84.55) 89.36 (63.82) 0.24 slalom 35.71 (24.10) 34.19 (28.09) 0.68 Triceps brachial Straightforward 190.46 (161.61) 145.79 (99.81) 0.02* slalom 91.44 (58.42) 87.45 (45.18) 0.57 Anterior deltoids Straightforward 281.16 (159.22) 224.37 (110.98) 0.04* slalom 124.23 (56.12) 98.29 (52.11) 0.01* Biceps brachial Straightforward 152.84 (56.42) 96.57 (48.31) 0.02* slalom 53.13 (37.88) 36.32 (18.59) 0.01* *p < 0.05. Note: EMG = electromyography. respective positions for each muscle in accordance with the SENIAM project (www.seniam.org) on the dominant side of the subject’s body to record the electrical activity of the muscles. Surface EMG data were sampled at 2048 Hz (which is more than double the frequency in human muscles) [19] to satisfy the Nyquist Theorem, and the root mean square (rms) value was calculated and transmitted by the T-Sens module. The frequency of the rms calcula- tion was128 Hz, and data analysis was performed with the CAPTIV L-7000 software (TEA Ergo, France). All EMG calculation was in mV and analyzed during the complete trajectory, and the first and last pushes were discarded, in order to analyze the muscle activity in plain motion. The mean time window of the analysis was 6.52 s for the straightforward motion and 31.23 s for the slalom. 2.3. Data analysis Mean values were obtained for the EMG measurements of the four muscles of all subjects. To verify statistical dif- ferences in the mean EMG of the four muscles between all of the wheelchair configurations for both trajectories, Friedman’s test was applied. To verify statistical differ- ence in paired data, the Wilcoxon test was applied, because the data did not show a normal distribution as revealed by the Shapiro–Wilk test. Significance was determined by p ≤ 0.05. All statistical analyses were performed using SPSS version 22.0. 3. Results The results show that wheelchair design and configura- tion can influence the load on the upper limbs. For the wheelchair with accessories, axle position was shown to be a factor that influences the biomechanical load on the upper limbs. In the straightforward sprint, the axle in the forward position showed lower activity than the rearward position in all of the muscles, with significant difference found in the triceps (p = 0.02), anterior deltoids (p = 0.04) and biceps (p = 0.02). This was also found in the slalom course, because propelling the chair with the axle in the forward position required less activity of all muscles in comparison with the rearward position, although signifi- cant difference was found only with the anterior deltoids (p = 0.01) and biceps (p = 0.01) ( Table 1). Conversely, the influence of axle position appeared to be minimized when propelling the chair with the acces- sories removed, because there was no significant difference regarding the axle position for both the straightforward sprint and the slalom course (Table 2). The differences in the muscle activity related to the wheelchair configurations (axle position and accessories) and trajectories can be interpreted by the ratio of the mean EMG for the forward and rearward axle positions, as pre- sented in Figure 4. Values lower than one indicate lower demand on the upper limbs during manual propulsion with the axle in a forward position, while values higher than one indicate the opposite, i.e., lower demand with the axle in a rearward position. 4. Discussion Wheelchair design and configuration are important factors that can influence the demand on the upper limbs during manual propulsion. This study addressed the influence of a file:www.seniam.org 314 G. da Silva Bertolaccini et al. Table 2. Mean EMG activity (mV) of the four muscles during manual wheelchair propulsion without the accessories. Muscle Trajectory Rearward axle Forward axle p Pectoralis major Straightforward 88.66 (71.58) 90.14 (82.33) 0.99 slalom 31.56 (24.85) 29.39 (19.63) 0.49 Triceps brachial Straightforward 183.35 (150.79) 192.24 (1342.43) 0.37 slalom 91.12 (56.36) 95.07 (54.59) 0.33 Anterior deltoids Straightforward 253.41 (131.53) 255.01 (150.73) 0.92 slalom 105.45 (54.30) 99.93 (49.05) 0.43 Biceps brachial Straightforward 109.78 (70.51) 123.74 (95.91) 0.30 slalom 40.93 (25.82) 39.64 (19.73) 0.99 Note: EMG = electromyography. Figure 4. Ratio (F/R) of the mean EMG for the forward (F) and rearward (R) axle positions. Note: EMG = electromyography. slight but relevant aspect – axle position – on the activity of upper limb muscles that many times is neglected during equipment design and setup. Because some users remove the accessories (armrest and clothing shields) in order to make the chair lighter, we investigated the influence of axle position in both situations: with and without accessories. Our results show that moving the axle position for- ward led to a decrease in the activity of upper limbs during manual wheelchair propulsion in both the straightforward sprint and the slalom course. However, this difference was significant only in the standard configuration (with accessories). Previous studies have highlighted the bene- fits of positioning the axle forward on the demand on the upper limbs [20,21]. From a mechanical perspective, mov- ing the axle forward reduces the length of the equipment, which impacts the rotational inertia of the system. Addi- tionally, moving the rear wheels forward may contribute to wheelchair mobility by reducing the rolling resistance, because the user’s body moves toward the rear wheels [22]. Although moving the rear wheels’ axle forward seems to provide an ergonomic benefit for the user in terms of facilitating manual propulsion, it must be taken into account that it has consequences on the equipment stabil- ity. In practice, the more forward the axle, the easier it is for the wheelchair to tip over. The guidelines for preserv- ing upper limb function after spinal cord injury recommend that the rear wheels’ axle must be positioned as forward as possible without compromising equipment stability [19]. This can only be set up with the participation of the user. Although the current study produced important find- ings, it has limitations that must be noted. First, procedures were not performed with real users, and only men partic- ipated in the study. Additionally, tasks were conducted at the highest speed the subjects could propel. Another lim- itation is that we did not assess the subjects’ perceptions of the efforts during manual wheelchair propulsion, which could demonstrate whether these changes in wheelchair design and configuration are perceived or not by the subjects. 5. Conclusion The wheelchair can enhance users’ mobility, independence and social participation, and small changes in its design and configuration can lead to important contributions to daily mobility. The current findings suggest that moving the rear wheels’ axle forward may have a positive effect on manual propulsion by decreasing the activity of upper limb muscles, although this was only found with the chair in its standard configuration (with accessories). This shows an existing correlation between wheelchair mechanics and propulsion biomechanics. From an ergonomic perspective, adjusting the equipment mechanics (resulting from differ- ent configurations) must be seen as a strategy to reduce the loads on the upper limbs, thus benefiting users’ mobility. International Journal of Occupational Safety and Ergonomics (JOSE) 315 This information may benefit designers, manufacturers and health professionals in the design, prescription and pro- visioning of manual wheelchairs. Providing a wheelchair with adjustable configurations – the current study focused on the axle position – may help the user to set up the chair in accordance with his/her characteristics, needs and expectations. Disclosure statement No potential conflict of interest was reported by the authors. Funding This work was supported by CAPES (Coordination for the Improvement of Higher Level Personnel); FAPESP (São Paulo Research Foundation) [grant no. 16/05026-6]; CNPq (National Council for Scientific and Technological Development) [grant no. 458740/2013-6]. Ethical approval All the study procedures were submitted and approved by the Ethics Committee of the Faculty of Architecture, Arts and Com- munication – UNESP (Process. N. 800.500). ORCID Fausto Orsi Medola http://orcid.org/0000-0003-2308-6524 References [1] Slowik JS, Requejo PS, Mulroy SJ, et al. The influence of wheelchair propulsion hand pattern on upper extremity mus- cle power and stress. J Biomech. 2016;49(9):1554–1561. doi:10.1016/j.jbiomech.2016.03.031 [2] Moon Y, Chandrasekaran J, Hsu IMK, et al. Variability of peak shoulder force during wheelchair propulsion in man- ual wheelchair users with and without shoulder pain. Clin Biomech (Bristol, Avon). 2013;28(0):1–16. [3] Desroches G, Dumas R, Pradon D, et al. Upper limb joint dynamics during manual wheelchair propul- sion. Clin Biomech (Bristol, Avon). 2010;25(4):299–306. doi:10.1016/j.clinbiomech.2009.12.011 [4] Aytar A, Zeybek A, Pekyavas NO, et al. Scapu- lar resting position shoulder pain and function in dis- abled athletes. Prosthet Orthot Int. 2015;39(5):390–396. doi:10.1177/0309364614534295 [5] Cavedon V, Zancanaro C, Milanese C. Kinematic analysis of the wheelchair tennis serve: implications for classifi- cation. Scand J Med Sci Sports. 2014;24(5):e381–e388. doi:10.1111/sms.12182 [6] Tomsone S, Haak M, Löfqvist M. Experiences of mobility device use over time: a multiple case study among very old Latvian women. Scand J Occup Ther. 2016;23(1):67–78. doi:10.3109/11038128.2015.1068850 [7] Brandt A, Kreiner S, Iwarsson S. Mobility-related participa- tion and user satisfaction: construct validity in the context of powered wheelchair use. Disabil Rehabil Assist Thechnol. 2010;5(5):305–313. doi:10.3109/17483100903394636 [8] Das B, Black NL. Isometric pull and push strengths of paraplegics in the workspace: 1. Strength measurement pro- files. Int J Occup Saf Ergon. 2000;6(1):47–65. doi:10.1080/ 10803548.2000.11076443 [9] Das B, Black NL. Isometric pull and push strengths of paraplegics in the workspace: 2. Statistical analysis of spatial factors. Int J Occup Saf Ergon. 2000;6(1):67–80. doi:10.1080/10803548.2000.11076444 [10] Troy BS, Cooper RA, Robertson RN, et al. An analysis of work posture of manual wheelchair users in the office environment. J Rehabil Res Dev. 1997;34(2):151–161. [11] Bohannon RW. Number of pedometer-assessed steps taken per day by adults: a descriptive meta-analysis. Phys Ther. 2007;87:1642–1650. doi:10.2522/ptj.20060037 [12] Karmarkar AM, Collins DM, Kelleher A, et al. Man- ual wheelchair-related mobility characteristics of older adults in nursing homes. Disabil Rehabil Assist Technol. 2010;5:428–437. doi:10.3109/17483107.2010.481346 [13] Tolerico ML, Ding D, Cooper RA, et al. Assessing mobility characteristics and activity levels of manual wheelchair users. J Rehabil Res Dev. 2007;44:561–571. doi:10.1682/JRRD.2006.02.0017 [14] Sonenblum SE, Sprigle S, Lopez RA. Manual wheelchair use: bouts of mobility in everyday life. Rehabil Res Pract. 2012. doi:10.1155/2012/753165 [15] Alm M, Saraste H, Norrbrink C. Shoulder pain in per- sons with thoracic spinal cord injury: prevalence and characteristics. J Rehabil Med. 2008;40:277–283. doi:10. 2340/16501977-0173 [16] Chaves ES, Boninger ML, Cooper R, et al. Assessing the influence of wheelchair technology on perception of par- ticipation in spinal cord injury. Arch Phys Med Rehabil. 2004;85:1854–1858. doi:10.1016/j.apmr.2004.03.033 [17] Medola FO, Dao PV, Caspall JJ, et al. Partitioning kinetic energy during freewheeling wheelchair maneu- vers. IEEE Trans Neural Rehabil Eng. 2014;22(2):326–333. doi:10.1109/TNSRE.2013.2289378 [18] Medola FO, Elui VMC, Santana CS, et al. Aspects of manual wheelchair configuration affecting mobility: a review. J Phys Ther Sci. 2014;26(2):313–318. doi:10.1589/ jpts.26.313 [19] Winter DA. Electromyogram recording, processing, and normalization: procedures and considerations. J Hum Mus- cle Perform. 1991;1(2):5–15. [20] Paralyzed Veterans of America Consortium for Spinal Cord Medicine. Preservation of upper limb function following spinal cord injury: a clinical practice guideline for health- care professionals. J Spinal Cord Med. 2005;28(5):434–470. doi:10.1080/10790268.2005.11753844 [21] Gorce P, Louis N. Wheelchair propulsion kinematics in beginners and expert users: influence of wheelchair settings. Clin Biomech (Bristol, Avon). 2012;27:7–15. doi:10.1016/j.clinbiomech.2011.07.011 [22] MacPhee AH, Kirby RL, Bell AC, et al. The effect of knee-flexion angle on wheelchair turning. Med Eng Phys. 2001;23:275–283. doi:10.1016/S1350-4533(01)00024-8 http://orcid.org/0000-0003-2308-6524 https://doi.org/10.1016/j.jbiomech.2016.03.031 https://doi.org/10.1016/j.clinbiomech.2009.12.011 https://doi.org/10.1177/0309364614534295 https://doi.org/10.1111/sms.12182 https://doi.org/10.3109/11038128.2015.1068850 https://doi.org/10.3109/17483100903394636 https://doi.org/10.1080/10803548.2000.11076443 https://doi.org/10.1080/10803548.2000.11076443 https://doi.org/10.1080/10803548.2000.11076444 https://doi.org/10.2522/ptj.20060037 https://doi.org/10.3109/17483107.2010.481346 https://doi.org/10.1682/JRRD.2006.02.0017 https://doi.org/10.1155/2012/753165 https://doi.org/10.2340/16501977-0173 https://doi.org/10.2340/16501977-0173 https://doi.org/10.1016/j.apmr.2004.03.033 https://doi.org/10.1109/TNSRE.2013.2289378 https://doi.org/10.1589/jpts.26.313 https://doi.org/10.1589/jpts.26.313 https://doi.org/10.1080/10790268.2005.11753844 https://doi.org/10.1016/j.clinbiomech.2011.07.011 https://doi.org/10.1016/S1350-4533(01)00024-8 1. Introduction 2. Materials and methods 2.1. Participants 2.2. Equipment and procedure 2.3. Data analysis 3. Results 4. Discussion 5. Conclusion Disclosure statement Funding Ethical approval ORCID References