The use of NGT methods generated novel ideas linked to the question and provided a focus for understanding user priorities at the outset of the co-design project. The NGT method elicited a list of suggested features to enhance the equipment and structured group discussion captured the importance of an individualised, science informed exercise programme. Expert consensus enabled the selection of three specific machines through token placement and ranking. The value of a motivating and progressive PAE programme which can be used independently was articulated by both expert groups. Areas of convergence between the expert groups were identified.
Value of diverse user involvement
The features associated with the proposed PAE programme combine elements of exercise training and therapeutic rehabilitation. The exercise scientists emphasised the training overload principle to elicit a physiological response; whereas the physiotherapists and EU group discussed the value of efficient, goal oriented, reciprocal movement patterns. The range of priorities expressed illustrated the value of consultation with diverse experts in the preliminary phase of the co-design project. Published exercise guidelines for PwS have focussed on improvements in aerobic capacity and muscular performance ; whereas physical rehabilitation for PwS has prioritised quality of movement and functional recovery . Assisted exercise enhances motor recovery and improves aerobic capacity for PwS  and therefore may bridge the historical gap which has existed between exercise and rehabilitation perspectives.
Embracing a digitalised future
The introduction of assistive technologies in rehabilitation has the potential to enable users to gain empowerment over their recovery and move towards a therapist-directed rather than therapist-dependent rehabilitation programme. Both expert groups emphasised the importance of a user-friendly interface which can be operated independently by the end user. Prioritised suggestions included motivational features, graded progression and real time feedback. Previous exploration of home-based technology through co-design with PwS also highlighted the value of user feedback, motivational gamification and independent use .
Assistive technologies may be perceived as detached and impersonal , the importance of an individualised user experience was articulated during the group discussions. In the context of PAE, an individualised user experience would facilitate the user to develop a bespoke relationship with the interface to enable an adaptable, goal-oriented exercise experience and access personalised digital information regarding progress and achievements. The emotional response triggered by interaction with technology may be influenced by the product’s quality, function and individual meaning . Customizable health technologies matched to the users’ needs and preferences has been identified as a priority .
Both groups embraced the prospect of a digitalised programme able to generate a numerical record of performance and achievement. The digitalisation of user data can enable remote supervision of rehabilitation programmes by healthcare professionals . However, a recent study to introduce wearable technologies to monitor activity amongst exercise referral scheme participants was abandoned due to poor recruitment and retention . Achieving the required balance between support, supervision and monitoring amongst older adults has been identified as a challenge by physiotherapists; individualised behaviour change interventions integrated with exercise prescription may enhance retention and reported experience .
Service and setting
Discussion regarding the setting and service was initiated by attendees during both NGT events. Attendees of the expert groups envisaged a client centred, accessible facility operated by knowledgeable staff. PwS have reported perceived improvement in physical performance and participation associated with venue-based exercise , although leisure service providers have reported feeling under-confident with the stroke population due to challenges associated with their ability to access standard exercise equipment . Assisted exercise programmes have been reported as acceptable and feasible for PwS in leisure settings and, for some participants, represented a stepping stone towards the use of conventional equipment .
The preferences shared by the members of the NGT enabled the selection of three machines from a range of nine to be prioritised for technological advancement. The EU group were all regular users of the range of equipment and their preference pattern suggested a level of appreciation for all nine machines in comparison to the PU group who indicated a greater preference for the machines which predominantly assisted limb movement. Our findings indicated that the EU group valued those machines which assist trunk movement and this highlighted the importance of capturing the perspective of the end user in decision making . Trunk control is an important predictor of mobility following stroke  and assistive interventions have been previously recommended to address deficits in trunk movement . The PU group expressed a preference for those machines which more closely resemble conventional gym equipment. The three prioritised machines include a combination of conventional and novel models, representing the views of all stakeholders. This divergence in opinion emphasised the importance of user involvement; continued engagement with PU and EU representatives will be sustained throughout the programme of research.
Application of nominal group technique to Patient Public Involvement
This user involvement report has shown the importance of early stakeholder engagement at the outset of a programme of research aimed at improving PAE for PwS. Historically, the way in which PPI has been conducted has been criticised as being tokenistic and professional led . NGT has been previously implemented in PPI activities  and, in our experience, enabled all attendees to share their perspectives, ideas, experiences and preferences. NGT enabled the adoption of a collective, direct and proactive model of PPI , which empowered PwS and service providers to shape key priorities and direct important decisions.
The research team acknowledge limitations associated with the NGT exercise reported in this paper. On reflection, a collective event which combined EU and PU representation may have generated cross fertilisation of perspectives and greater depth of discussion. Subsequent user involvement methods employed during stage two of the design project did integrate PU with EU groups. Some experience of using PAE equipment was considered necessary to be eligible as an expert by experience. This limited the number of PwS able to make an informed contribution to the events, and of the five identified experts by experience, only three were able to attend. All of the EU attendees with stroke were female and had committed to investment in their recovery through third sector exercise and rehabilitation services, the opinions and preferences expressed may not have been representative of the wider stroke population. Narrow user representation has been previously reported as a limitation in patient involvement in health technology funding decisions . It was also noted that there was a gender split across the PU group, with an all-male representation from the exercise scientists and all-female group of physiotherapists. Future activities should aim for an optimal balance of representation to promote equality and diversity of perspectives shared.
However, this report exemplifies how NGT can generate a vision for an intelligent, individualised, goal orientated technology centred around users’ preferences and priorities. In the context of this project is facilitated the development of more targeted digitalisation of PAE machines for PwS which are subsequently more likely to be acceptable to the user population. The use of NGT enables the capture a range of perspectives which can enrich research design and implementation.