Title: 1st Workshop on Upper-Extremity Assistive Technology for People with Duchenne: State of the art, emerging avenues, and challenges
Abstract: •There is a need for comparative studies based on requirements and outcome measures.•There is a low acceptance rate of commercially available devices.•Advanced robotic arm supports are still in experimental phase. The 1st workshop on Assistive Technology for People with Duchenne Muscular Dystrophy (DMD) was held in London (United Kingdom), on April 27th 2015. The primary goal was to bring people from different disciplines together and discuss opportunities to accelerate the development of upper-extremity assistive technology for enhancing the functional abilities of non-ambulant men with DMD. The topics of the workshop included the state of the art, emerging avenues and challenges of upper-extremity assistive technology. Twenty-four participants representing parents, experts in user requirements, human-machine research, electrical and mechanical engineering, and clinicians involved in the care of children with Duchenne muscular dystrophy from Denmark, the Netherlands, the UK and the USA, participated in the workshop. Key results included the identification of the need for comparative studies based on standard requirements and outcome measures, and the low acceptance rate of commercially available devices. Advanced robotic arm supports are still in experimental phase. Finally, focus groups were initiated on (1) evidence based user requirements and acceptance, (2) assessment protocols, (3) modular technology, and (4) accessibility and reimbursement. DMD is a progressive muscle disorder, characterized by muscle wasting and weakness. The first signs of the disease is ambulatory delay, with 50% of DMD boys starting to walk after 18 months [[1]Emery A.E.H. The muscular dystrophies.Lancet. 2002; 359: 687-695Abstract Full Text Full Text PDF PubMed Scopus (1151) Google Scholar]. DMD leads to full time use of a wheelchair in the mid-teens, loss of upper-extremity (UE) function in the late-teens followed by the development of cardiomyopathies and respiratory failure [1Emery A.E.H. The muscular dystrophies.Lancet. 2002; 359: 687-695Abstract Full Text Full Text PDF PubMed Scopus (1151) Google Scholar, 2Muntoni F. Cardiomyopathy in muscular dystrophies.Curr Opin Neurol. 2003; 16: 577-583Crossref PubMed Scopus (83) Google Scholar]. Currently, there is no cure for DMD, and treatment is mainly aimed at delaying disease progression and preserving functional abilities. Due to these new treatments (including nocturnal ventilation), life expectancy in boys with DMD has increased from 14 years of age in the 1960s to 25 years of age in the 1990s [3Eagle M. Baudouin S.V. Chandler C. Giddings D.R. Bullock R. Bushby K. Survival in Duchenne muscular dystrophy: improvements in life expectancy since 1967 and the impact of home nocturnal ventilation.Neuromuscul Disord. 2002; 12: 926-929Abstract Full Text Full Text PDF PubMed Scopus (738) Google Scholar, 4Simonds A.K. Muntoni F. Heather S. Fielding S. Impact of nasal ventilation on survival in hypercapnic Duchenne muscular dystrophy.Thorax. 1998; 53: 949-952Crossref PubMed Scopus (350) Google Scholar]. Currently, the median survival of boys with DMD is estimated to be over 30 years [5Eagle M. Bourke J. Bullock R. et al.Managing Duchenne muscular dystrophy–the additive effect of spinal surgery and home nocturnal ventilation in improving survival.Neuromuscul Disord. 2007; 17: 470-475Abstract Full Text Full Text PDF PubMed Scopus (248) Google Scholar, 6Kohler M. Clarenbach C.F. Bahler C. Brack T. Russi E.W. Bloch K.E. Disability and survival in Duchenne muscular dystrophy.J Neurol Neurosurg Psychiatry. 2009; 80: 320-325Crossref PubMed Scopus (150) Google Scholar] and it is expected that the life expectancy will continue to increase. Because of the prolonged life expectancy, the number of individuals living with DMD is increasing. This group of young men lives with impaired UE function for more than 15 years, which severely limits the performance of basic activities of daily living (like self-feeding and personal care) and restrict social participation. It is generally accepted in the DMD community that early and combined efforts of steroids and bracing to preserve leg strength are rewarded by a longer ambulatory period. There is also evidence that suggests that certain assisted arm training delays the progression of muscle weakness in the arms [[7]Jansen M. van Alfen N. Geurts A.C. de Groot I.J. Assisted bicycle training delays functional deterioration in boys with Duchenne muscular dystrophy: the randomized controlled trial "no use is disuse.Neurorehabil Neural Repair. 2013; 27: 816-827Crossref PubMed Scopus (103) Google Scholar]. The use of assistive devices has the potential to improve the quality of life for people with DMD, by enabling them to continue performing activities of daily living and participate in social activities. Between 1936 and 2011 [[8]Van der Heide L.A. van Ninhuijs B. Bergsma A. Gelderblom G.J. van der Pijl D.J. de Witte L.P. An overview and categorization of dynamic arm supports for people with decreased arm function.Prosthet Orthot Int. 2014; 38: 287-302Crossref PubMed Scopus (44) Google Scholar], more than 100 UE assistive devices have been developed. Most of them are intended for rehabilitation to regain strength and motor control, and few are designed to assist during activities of daily living. UE assistive devices for daily use are also known as dynamic arm supports. Despite all the developmental efforts, few devices are commercially available. Van der Heide et al. [[9]van der Heide L.A. Gelderblom G.J. de Witte L.P. Effects and effectiveness of dynamic arm supports: a technical review.Am J Phys Med Rehabil. 2015; 94: 44-62Crossref PubMed Scopus (22) Google Scholar] concluded that only a few number of dynamic arm supports that have been developed have also been evaluated. Most of the studies that they found examined the effects of dynamic arm supports on body functions, activities, and participation under laboratory conditions. Although, in general, these studies report positive outcomes, the number of users of dynamic arm supports appears to be low. Researchers have mentioned various possible reasons that could be the cause of the low number of users: preference of compensatory movements over using an assistive device, large dimensions of the devices that stigmatize the user, difficulties in adjusting the device, clinical deterioration and expense. Besides efficacy evaluation under laboratory conditions, a much better understanding of effectiveness of using dynamic arm supports in daily life is needed [[9]van der Heide L.A. Gelderblom G.J. de Witte L.P. Effects and effectiveness of dynamic arm supports: a technical review.Am J Phys Med Rehabil. 2015; 94: 44-62Crossref PubMed Scopus (22) Google Scholar]. Elizabeth Vroom presented what the highest priorities are for young men with DMD. In order to improve quality of life for those living with Duchenne, independence and participation must be facilitated. For young men, it is important to be able to participate in work and social activities. While privacy is indicated as being important, socialization and employment are priorities as well. In 2007, the Dutch Duchenne Parent Project organized a workshop to determine whether improving arm or leg function should be prioritized. The outcomes of this workshop were that young men considered arm function as the highest priority. The loss of lower extremity function can be compensated fairly well by using a wheelchair, but compensating the loss of arm function is less evident [[10]Janssen M.M. Bergsma A. Geurts A.C. de Groot I.J. Patterns of decline in upper limb function of boys and men with DMD: an international survey.J Neurol. 2014; 261: 1269-1288Crossref PubMed Scopus (71) Google Scholar]. Although complete loss of arm function arises at the late-teens, it has been shown that performing activities with the arms is already limited in the late ambulatory stage and that participating in school activities is also restricted because of these limitations [[10]Janssen M.M. Bergsma A. Geurts A.C. de Groot I.J. Patterns of decline in upper limb function of boys and men with DMD: an international survey.J Neurol. 2014; 261: 1269-1288Crossref PubMed Scopus (71) Google Scholar]. When young men with Duchenne were asked what a new drug should gain in terms of daily activities, the responses were related to the activities that can be achieved with the arms: touching the face, self-feed, personal care such as brushing teeth, toileting, use of computer, and the ability to maneuver wheelchair are considered of high value. Individuals with DMD expressed an urgent need for privacy, which becomes impossible as weakness increases. Two user requirements studies have been performed to determine what activities are considered to be most important. Annie Kennedy presented the results from a study performed by the PPMD in the USA. The results from focus groups sessions were combined with an online survey that was distributed in the USA (N = 19), to determine priorities of ambulant and non-ambulant people with DMD. The priority activities for the ambulant group were stand up, pick up objects from the floor and walk upstairs. The priority activities for the non-ambulant group were repositioning at night, bring hands to mouth, shift while seated, using joystick and using the keyboard of a computer. Imelda de Groot presented the results from a World-wide survey. In this survey, 213 individuals (age ranging from 1.5 to 35.2 years old) with DMD participated, of which 95 were ambulant and 118 non-ambulant. From this survey, it was concluded that the main priority is to eat independently and prepare food. Subsequently, activities that were indicated to be important by the ambulant respondents were getting dressed, reaching objects or lifting objects and writing. Activities that were indicated being important by the non-ambulant respondents were personal hygiene, drinking and using a computer [[10]Janssen M.M. Bergsma A. Geurts A.C. de Groot I.J. Patterns of decline in upper limb function of boys and men with DMD: an international survey.J Neurol. 2014; 261: 1269-1288Crossref PubMed Scopus (71) Google Scholar]. •Arm function is highly important. More insight in ADLs that should be supported and what people require from an arm support is needed. Current surveys address what young men value (e.g., use of computer). It is important to reach out more broadly in getting input into device design – it might just be that we are currently sampling a small portion of the population who is willing to test a novel device. It is also important to consider potential users in the full range of the progression, from early through late loss of ambulation.•Studies on technical requirements are needed (e.g. required movement speed, number of degrees of freedom, range of motion of each joint). While there is a considerable variety of upper-extremity assistive devices, there are few studies that investigate the user requirements. One example is the study by Ramanathan et al. [[11]Ramanathan R. Eberhardt S.P. Rahman T. Sample W. Seliktar R. Alexander M. Analysis of arm trajectories of everyday tasks for the development of an upper-limb orthosis.IEEE Trans Rehabil Eng. 2000; 8: 60-70Crossref PubMed Scopus (21) Google Scholar], which analyzes the arm trajectories of healthy subjects during ADL to find what are the movements that an arm support device should assist.•The use of two arms may be preferred over one arm, since a lot of ADL are bimanual tasks. Current devices are essentially for one arm; therefore, bimanual application doubles the price. Insurance companies typically reimburse at most one arm support.•Patient organizations have a crucial role in putting patients first, encouraging collaborations, recognizing unmet needs, determining which initiative has the highest priority, gaining leverage for research funding, stimulating regulatory approval, improving the access of technology and advocating for the reimbursement of devices. In order to optimize devices and assess effectiveness of devices, quantitative and objective evaluation methods are needed. Quantitative data comprises kinematic parameters, such as the range of motion of supported arm movements and the muscle effort that is needed to using a particular type of arm support. Individuals with DMD need relatively more effort in all directions in order to perform the same movements as healthy controls. Also, they recruit more muscles simultaneously for all motions. One key question is whether muscle activation requirements or the amount of energy required to perform a specific activity will become lower by using the assistive device. In the same World-wide survey (N = 213) that was presented by Imelda de Groot, changing patterns of arm function during the course of DMD were investigated. The questionnaire included the domains of pain and stiffness in the arms, activity limitations and restrictions in social participation. In general, pain, stiffness, and activity limitations increased with disease stage. The researchers found that activity limitations in the arms already occurred in the early ambulatory stage, and that these limitations affected their social participation. About 70% of the respondents experienced limitations when performing social activities. Only 9% of the respondents on the other hand used supportive aids [[10]Janssen M.M. Bergsma A. Geurts A.C. de Groot I.J. Patterns of decline in upper limb function of boys and men with DMD: an international survey.J Neurol. 2014; 261: 1269-1288Crossref PubMed Scopus (71) Google Scholar]. Progressive muscle weakness results in reduction of physical activity and disuse of the musculoskeletal and cardiorespiratory systems, because performing activities cost more and more energy [[12]McDonald C.M. Physical activity, health impairments, and disability in neuromuscular disease.Am J Phys Med Rehabil. 2002; 81: S108-20Crossref PubMed Scopus (152) Google Scholar]. In addition, the use of a motorized wheelchair and a sedentary lifestyle further restricts the arm function, resulting in secondary physical deterioration and disuse. To decrease the deterioration due to disuse, arm training is considered [[13]Jansen M. de Groot I.J. van Alfen N. Geurts A. Physical training in boys with Duchenne Muscular Dystrophy: the protocol of the no use is disuse study.BMC Pediatr. 2010; 10: 55PubMed Google Scholar]. There is evidence that assisted bicycle-like motion training of the legs and arms is feasible and safe for both ambulant and wheelchair-dependent children [[7]Jansen M. van Alfen N. Geurts A.C. de Groot I.J. Assisted bicycle training delays functional deterioration in boys with Duchenne muscular dystrophy: the randomized controlled trial "no use is disuse.Neurorehabil Neural Repair. 2013; 27: 816-827Crossref PubMed Scopus (103) Google Scholar]. Recently, a training study in DMD was conducted, in which participants received a training program with a dynamic arm support. The training was based on a virtual reality computer game, in which participants had to perform several ADL while using dynamic arm support. Six boys finished the study and in four of these six boys, the trained arm retained more motor function than the untrained arm. These preliminary findings may indicate that boys with DMD can safely train their arms with dynamic arm support [[14]Jansen M. Burgers J. Jannink M. van Alfen N. de Groot I.J.M. Upper limb training with dynamic arm support in boys with Duchenne muscular dystrophy: a feasibility study.Int J Phys Med Rehabil. 2015; 3 (epub ahead)Google Scholar]. Jay Han presented part of his work on measuring reaching workspace. In order to quantify the reachable workspace, various methods can be used. One promising method is the Kinect-acquired reachable workspace measure, developed at the University of California. This method comprises a scalable and affordable sensor-based upper extremity reachable workspace assessment system using a Kinect sensor [15Kurillo G. Chen A. Bajcsy R. Han J.J. Evaluation of upper extremity reachable workspace using Kinect camera.Technol Health Care. 2013; 21: 641-656PubMed Google Scholar, 16Kurillo G. Han J.J. Obdrzalek S. et al.Upper extremity reachable workspace evaluation with Kinect.Stud Health Technol Inform. 2013; 184: 247-253PubMed Google Scholar]. This quantitative reachable workspace outcome measure has demonstrated applicability as a novel surrogate marker of upper extremity function in DMD and Becker Muscular Dystrophy (BMD) [[17]Han J.J. Kurillo G. Abresch R.T. De Bie E. Nicorici A. Bajcsy R. Upper extremity 3-dimensional reachable workspace analysis in dystrophinopathy using Kinect.Muscle Nerve. 2015; 52: 344-355Crossref PubMed Scopus (36) Google Scholar]. In a series of preliminary studies, the reachable workspace outcome measure has shown its validity, reliability, and sensitivity, as well as clinical-meaningfulness by correlating strongly with person-reported activities of daily living (ADL) function. Additionally, the Kinect-acquired reachable workspace measure demonstrated its utility in both ambulatory and non-ambulatory individuals as well as pediatric and adult populations with DMD/BMD, providing for the first time, a means to follow progression of the disease through important clinically-meaningful functional milestones, such as both the loss of ambulation and ability to self-feed, through the lifespan of an individual with DMD or BMD. The impact of the novel upper extremity assessment tool and outcome measure will be most directly felt in clinical trials where it will facilitate: 1) access to clinical studies for non-ambulatory individuals, 2) reduction of study participant burden, 3) improvement in efficiency through automation, 4) home-based data collection via internet-connected sensor, and 5) better evaluation of efficacy for interventions; all contributing to potentially transform the way clinical trials are conducted in DMD/BMD. However, improved quantitative measurements of upper extremity with its correlative clinical data will also have implications for intervention development in the robotics field. The kinematic and dynamic parameters obtained across a large cohort with a spectrum of disease severity and functional levels can be used to inform design of assistive devices, robots, and exoskeletons. The data will also be informative in general model building as well as refining models of upper extremity function. Identification of individual requirements/needs and functional parameters will contribute to a more 'personalized' and prescriptive robotic system that will be optimized and tailored to individual functional needs. •Arm function progression studies: Monitoring the disease progression is needed so that engineers know what level of assistance is needed as a function of time (per day, per year) in arm supports. To this end, modeling may be useful to estimate individual muscle function.•How much support is needed: A current problem is that the arms are often disused, which results in deterioration of muscle capacity. Once people with DMD lose ambulation, the arm use is reduced. The general consensus was to keep using the arms, but also that overuse should be avoided. There is a need to address upper extremity function, with titrating how much assistance is given. Although it is not scientifically clear when there is overuse, fatigue, pain and no functional return the next day are associated with upper extremity overuse and can be used to help titrate the amount of assistance required.•There is a need for outcome measures to evaluate arm function in a daily life setting: Currently, insufficient objective data are available to evaluate how much the arms are used/burdened during the day. Also, longitudinal studies are missing.•Therapeutic effects: Pilot studies suggest that there may be a therapeutic effect when a person regularly uses an arm support. How does this therapeutic effect relate with the quality of life of the users? Is it necessary to prevent overuse of the arms? The first arm supports were developed in the 1960's [[8]Van der Heide L.A. van Ninhuijs B. Bergsma A. Gelderblom G.J. van der Pijl D.J. de Witte L.P. An overview and categorization of dynamic arm supports for people with decreased arm function.Prosthet Orthot Int. 2014; 38: 287-302Crossref PubMed Scopus (44) Google Scholar]. While the first designs only supported eating movements, current devices assist a wide range of ADL. Up to date, there is a large number of UE assistive devices that have been developed, but only few are intended for daily use, commercially available and used by people with DMD. Extensive reviews can be found in References [[8]Van der Heide L.A. van Ninhuijs B. Bergsma A. Gelderblom G.J. van der Pijl D.J. de Witte L.P. An overview and categorization of dynamic arm supports for people with decreased arm function.Prosthet Orthot Int. 2014; 38: 287-302Crossref PubMed Scopus (44) Google Scholar] and [[18]Dunning A.G. Herder J.L. A review of assistive devices for arm balancing.2013Crossref Scopus (26) Google Scholar]. Dynamic arm supports can be divided into two subcategories [15Kurillo G. Chen A. Bajcsy R. Han J.J. Evaluation of upper extremity reachable workspace using Kinect camera.Technol Health Care. 2013; 21: 641-656PubMed Google Scholar, 16Kurillo G. Han J.J. Obdrzalek S. et al.Upper extremity reachable workspace evaluation with Kinect.Stud Health Technol Inform. 2013; 184: 247-253PubMed Google Scholar], non-powered (also called passive, or body-powered devices) and powered devices (also known as active or externally-powered devices). Non-powered arm supports use elastic elements (i.e. springs) to compensate the weight of the arm. Tariq Rahman, Paul Verstegen and Blake Mathie presented the developments of the WREX, the arm supports of Focal Meditech and the X-Ar respectively. The WREX (JAECO Orthopedic, USA) [[19]Rahman T. Sample W. Seliktar R. Alexander M. Scavina M. A body-powered functional upper limb orthosis.J Rehabil Res Dev. 2000; 37: 675-680PubMed Google Scholar] and the TOP (Focal Meditech BV, the Netherlands [[20]Focal Meditech BV Dynamic Arm Supports.http://www.focalmeditech.nl/en/dynamic-arm-supportsDate: 2016Google Scholar]) arm supports are non-powered arm supports that have been in the market for more than 20 years. The WREX (JAECO Orthopedics, USA) is now available in two versions: the metal version that attaches to the wheelchair or to a table, and a wearable version that combines 3D printed plastic parts and metal parts, known as Baby WREX, for ambulatory children [[21]Haumont T. Rahman T. Sample W. et al.Wilmington robotic exoskeleton: a novel device to maintain arm improvement in muscular disease.J Pediatr Orthop. 2011; 31: e44-9Crossref PubMed Scopus (67) Google Scholar]. More recent commercially-available non-powered arm supports include the SLING, the Dowing and the Balancer (Focal Meditech BV, the Netherlands [[20]Focal Meditech BV Dynamic Arm Supports.http://www.focalmeditech.nl/en/dynamic-arm-supportsDate: 2016Google Scholar]), the VERTICAL M.A.G (Proteor, France), the Nitzbon Mobility Arm (Nitzbon, Germany), the Saebo MAS (Saebo Inc., USA) and the X-Ar (Talem Technologies, USA [[22]Talem Technologies LLC X-Ar.http://www.talemtech.com/x-ar/Date: 2016Google Scholar]). Powered arm supports use motors to change the settings of the gravity compensation mechanism or to move the arm in the vertical or horizontal plane using a joystick or buttons. The TOP arm support can be extended with an actuator, called HELP, to provide active support in the vertical direction to assist persons with more severe muscle weakness. Beside the TOP/HELP, Focal Meditech has developed the active version of the Sling, Darwing and the GoWing. Other powered arm supports include the Armon (Microgravity Products, NL) [[23]Herder J.L. Vrijlandt N. Antonides T. Cloosterman M. Mastenbroek P.L. Principle and design of a mobile arm support for people with muscular weakness.J Rehabil Res Dev. 2006; 43: 591-604Crossref PubMed Scopus (70) Google Scholar], the Zonco Mobile Arm Valet (ZoncoArm, USA) [[24]ZoncoArm ZoncoArm Supports.http://www.zoncoarm.com/products.htmDate: 2016Google Scholar], the DAS (Exact Dynamics, the Netherlands) [[25]Kramer G. Romer G.R.B. Stuyt H.J.A. Design of a Dynamic Arm Support (DAS) for gravity compensation.2007: 1042-1048Google Scholar] and the Neater Arm support (Neater Solutions, UK) [[26]Michaelis J. Introducing the Neater Eater.Action Res. 1988; 6: 2-3Google Scholar]. A recent systematic review on the effect, effectiveness and usability of arm supports concluded from the results of 47 evaluation studies that there was an increased ability to perform activities of daily living and user satisfaction when using an arm support, but that the use of dynamic arm supports at home was low [[9]van der Heide L.A. Gelderblom G.J. de Witte L.P. Effects and effectiveness of dynamic arm supports: a technical review.Am J Phys Med Rehabil. 2015; 94: 44-62Crossref PubMed Scopus (22) Google Scholar]. A recent study of a questionnaire-based evaluation of the WREX concluded that the WREX made a significant improvement in arm function for users while performing everyday tasks. Sixty percent of the 55 users included in the study continued to use the WREX at the time of the survey. Sixty-nine percent of wheelchair-mounted WREX users continue to use it, and 48% of body-mounted continue to use it. Reasons for abandonment included weight, interference with other activities, joint contractures, and imprecise gravity compensation. Users showed more improvement of arm function with the wheelchair-mounted WREX than the body-mounted model. Aesthetics, fitting, and reimbursement were identified as areas for improvement [[27]Gunn M. Shank T. Eppes M. Hossain J. Rahman T. User Evaluation of a Dynamic Arm Orthosis for People With Neuromuscular Disorders.2015Google Scholar]. Furthermore, a user evaluation study with the Neater arm support concluded that the use of the Neater arm support by adults and teenagers with neuromuscular disorders could greatly improve their independence, confidence, and ability to engage in social situations [[28]Kumar A. Phillips M.F. Use of powered mobile arm supports by people with neuromuscular conditions.J Rehabil Res Dev. 2013; 50: 61-70Crossref PubMed Scopus (26) Google Scholar]. In addition to currently available devices there are several initiatives that aim to develop solutions that better suit the needs of young men with DMD. Among these initiatives are: the A-Gear project (DPP-Flextension, The Netherlands), the ReachABLE project (New Jersey Institute of Technology, USA) and the [email protected] project (Aalborg University, Denmark). Micha Paalman and Joan Lobo-Prat presented the work done in the Flextension A-Gear project. The Flextension A-Gear project started in 2011 with the goal of developing an inconspicuous arm support that could adapt to the growing needs of people with DMD. The development towards the ultimate arm support was divided in two separate functional prototypes: the Passive A-Gear and the Active A-Gear, which are directly related to two levels of assistance. The Passive A-Gear is intended for younger individuals that are still able to perform activities of daily living when the weight of the arms is compensated. The Passive A-Gear, in contrast to the existing arm supports, has a mechanical structure that closely follows the biomechanics of the arm and trunk, uses a novel spring configuration to balance the weight of the arm, and has a hip joint incorporated to allow flexion/extension movements of the trunk [[29]Kooren P.N. Dunning A.G. Janssen M.M. et al.Design and pilot validation of A-gear: a novel wearable dynamic arm support.J Neuroeng Rehabil. 2015; 12: 83Crossref PubMed Scopus (32) Google Scholar]. When the support provided by the Passive A-Gear becomes insufficient, the Active A-Gear will provide the extra assistance in weaker individuals with DMD using motorized joints. In order to operate active arm supports, the user needs to communicate his motion intention to the device through a control interface. The selection of the control interface in response to specific user needs and capabilities is a crucial determinant of the usability of the arm support. In previous studies, we have shown that the use of electrical activity of arm muscles (known as surface electromyography, sEMG) or the measurement of small forces that are still generated by the muscles, are both suitable signals to derive the motion intention of the adults with DMD with very limited arm function and control active arm supports [[30]Lobo-Prat J. Kooren P.N. Janssen M.M.H.P. et al.Implementation of EMG- and Force-based Control Interfaces in Active Elbow Supports for Men with Duchenne Muscular Dystrophy: a Feasibility Study.2016Google Scholar]. When using force-based control it is crucial to accurately distinguish the voluntary forces from the intrinsic forces of the arm such as gravity, inertia or stiffness forces. Especially for persons with a severe muscle weakness, the intrinsic forces of the arm have to be compensated. An alternative method is EMG-based control. Although the use of muscle activity is less intuitive, the EMG signals are not affected by the intrinsic properties of the arm such as stiffness, and therefore directly represent the motion intention of the user. On the other hand, disadvantages of EMG-based control include the poor long-term signal. In Reference [[30]Lobo-Prat J. Kooren P.N. Janssen M.M.H.P. et al.Implementation of EMG- and Force-based Control Interfaces in Active Elbow Supports for Men with Duchenne Muscular Dystrophy: a Feasibility Study.2016Google Scholar] we found that while movements with the force-based control were smoother and faster, EMG based-control was perceived as less fatiguing. Madeline Corrigan gave an overview