Table 4. Summary of REGAIN intervention components and theoretical underpinnings.

Intervention component	Aims	Theoretical Framework(s)	Behaviour Change Taxonomy
One to one consultation	To gather relevant information (clinical history) To assess motivations and potential barriers to engagement with the REGAIN Intervention To demonstrate and introduce the online platform To offer an opportunity to answer any questions related to the study or intervention and discuss home environment for engagement with the sessions	COM-B Self-efficacy Communication	Goal setting (behaviour) Restructuring the physical environment Instruction on how to perform a behaviour (online platform) Verbal persuasion about capability (if appropriate)
Support session 1 Introduction, expectations, motivation and goal setting	To introduce and familiarise participant with the programme Getting to know the group Explore personal and group expectations allowing time for planning, prioritising and setting achievable targets Explore motivation, understanding potential short term and long-term benefits of engagement in the programme	COM-B Social Learning Theory Bio-Psycho-Social	Goal setting (behaviour) Goal setting (outcome) Action planning
Group session 2 Fear avoidance and pacing	To introduce relationship between thoughts, feelings, and emotions related to avoidance of behaviour (for example fear of aggravating COVID-19 symptoms such as breathlessness/ fatigue) Exploring reasons for fear avoidance and consequences on health outcomes Exploring strategies to overcome fear avoidance and introduce pacing of activities	COM-B Self-Efficacy Bio-Psycho-Social	Information about antecedents Problem solving
Group session 3 Recovery and sleep, sleep management strategies	To explore how sleep patterns may have changed since having COVID Understanding sleep Introduction of sleep management strategies	COM-B Bio-Psycho-Social	Information about health consequences Problem solving Re-attribution
Group session 4 Management of emotions (perceived stigma, mood/ unhelpful thoughts)	To introduce and explore the impact of COVID on mood, thoughts and behaviour including unhelpful thought patterns Introduce skills for reframing thoughts, encouraging engagement with all components of the programme	COM-B Cognitive Behavioural Principles	Social support (emotional) Information about emotional consequences Monitoring of emotional Consequences Framing/reframing
Group session 5 Understanding stress and anxiety and management strategies	To understand and explore impact of stress on symptom management (acute vs chronic stress) Understand own stress response to COVID and hospitalisation Introduce stress management strategies	COM-B Bio-Psycho-Social	Information about social and environmental consequences Reduce negative emotions
Group Session 6 Managing setbacks and long-term behaviour change and future goals.	To consolidate learning from previous sessions and reinforce long term behaviour change To introduce management of setbacks and strategies of problem solving for long term change	COM-B Group Based Learning Self-management	Problem solving Review behaviour goal(s) Social support (emotional) Comparative imagining of future outcomes Self-talk Focus on past success
Practitioner handbook	To provide step-by-step guidance on delivering the REGAIN intervention To provide facilitation skills and motivational interviewing prompts and questions for group sessions	COM-B Motivational Interviewing	Feedback on behaviour (through quality assessment and observations of sessions) Credible source
Participant workbook	Provide information on programme structure, safety and contact information for further support if needed Provide information and content for each session, with clear aims, and tasks to complete to consolidate learning To allow a log of personal progress and reflection and point of reference during the programme and beyond	COM-B Self-Efficacy Bio-Psycho-Social	Self-monitoring of outcome(s) of behaviour Information about health consequences Behavioural practice/rehearsal
Live group exercise sessions	To increase ability to engage in physical activity To increase strength, flexibility, balance and aerobic capacity. To increase confidence in ability to move and engage in physical activity To encourage physical activity outside of live sessions. To strengthen group dynamics	COM-B Self-Efficacy Group Based Learning Social Learning Theory	Feedback on outcome(s) of behaviour Instruction on how to perform a behaviour Demonstration of the behaviour Graded tasks Body changes
On demand exercise Videos	To increase ability to engage in physical activity To increase strength, flexibility, balance and aerobic capacity. To increase confidence in ability to move and engage in physical activity To encourage physical activity outside of live sessions.	COM-B Self-Efficacy	Demonstration of the Behaviour Instruction on how to perform a behaviour Behavioural practice/rehearsal Body changes
Other on demand videos; breathing technique, mindfulness	To provide advice and education on relevant topics. To provide associated skills/behaviours to promote engagement in physical activity To increase confidence in ability to move and engage in physical activity	COM-B Self-Efficacy	Demonstration of the Behaviour Instruction on how to perform a behaviour Behavioural practice/Rehearsal Distraction