Table 1 Feasibility metrics, proposed methodology, and importance to future research in multiple sclerosis

Process (i.e., participant recruitment, retention, and adherence assessment)

1. Recruitment and refusal rates

2. Retention and attrition rates

3. Adherence rates to study procedures, intervention attendance, and engagement

1. Flyers and presentations at local and regional support group chapters, National Multiple Sclerosis Society events, clinics and doctor’s offices, advertisements on social media, email communication, and word of mouth will be used to recruit potential participants. All contact methods with potential participants and refusal reasons will be recorded.

2. The flow of participants through the recruitment, enrollment, and intervention stages of the study will be recorded.

3. Adherence rates will be recorded via individual log books.

1. Provides information for optimizing recruitment methods, anticipated recruitment numbers, and refusal reasons.

2. Specifies focal areas for enhancing participant retention.

3. Provides target areas for optimizing adherence to the intervention.

Resource (i.e., time and monetary needs assessment)

1. Staff training requirements

2. Communication time and content requirements and alterations

3. Recruitment and intervention time requirements

4. Monetary research costs

1. Staff training needs will be recorded.

2. A password-protected database will be used to monitor all contact between participants and staff members. Communication type, purpose, and any alterations will be recorded

3. Detailed staff time requirements for recruitment, testing, and training will be recorded. Individual log books will be used to record individual testing and training requirements for each participant.

4. All study-related monetary costs will be recorded.

1. Details staff training requirements.

2. Establishes communication frequency and quality and emphasizes communication problems. Details communication needs and anticipated communication problems.

3. Details staff and participant time requirements for delivering and engaging in the intervention, respectively.

4. Determines monetary cost to conduct the research and establishes areas for cost saving.

Management (i.e., data management and safety reporting assessment)

1. IRB approval procedures

2. Time and accuracy in data collection, entry, and checking

1. All Institutional Review Board (IRB) approval procedures will be documented and will include communications between the University IRB and staff, and time from submission of IRB application to approval.

2. Data will be checked for completeness and errors. All time spent collecting, entering, and checking data will be recorded.

1. Details procedural and staff requirements for obtaining ethical approval, compliance, and monitoring. Highlights optimal safety procedures to be implemented.

2. Identifies staff time requirements and highlights considerations for alterations to ensure proper data management.

Scientific (i.e., safety, burden, and treatment effect assessment)

1. Adverse events, serious adverse events, and clinical emergencies

2. Participants’ experience, burden, and perceptions

3. Treatment effect

1. Adverse events, serious adverse events, and clinical emergencies will be reported and recorded. A safety plan will be enacted in the occurrence of an adverse event wherein participants will be asked to discontinue the HIIT exercise and cool-down (if currently exercising) and will be required to be free of symptoms for at least 48 h before returning to activity.

2. Participants’ experience, burden, and perceptions of intervention appropriateness will be assessed via a short survey at the end of the intervention.

3. Treatment effects will be determined via effect size and clinical meaningfulness calculations of any change in the efficacy outcome variables.

1. Establishes the safety and feasibility of the intervention and identifies considerations for alterations.

2. Determines the acceptability and highlight considerations for alterations. Identifying compliance will further allow correct conclusions to be drawn from the results.

3. Establishes data for power calculations and projected clinical impact.