BACKGROUND: High intensity interval training (HIIT) has been identified as potential stimulus for eliciting health-promoting physical activity in an efficient manner among persons with multiple sclerosis (MS). The current study aimed to examine the feasibility and initial efficacy of a 12-week HIIT program using a recumbent stepper (RSTEP) in persons with MS who have walking disability. Feasibility outcomes of interest included process (i.e., recruitment, adherence, and retention rates), resource (i.e., time and monetary costs), management (i.e., data management and safety reporting assessment), and science (i.e., safety, burden, and treatment effect assessment). We hypothesized that 12-weeks of HIIT will be feasible via meeting a priori benchmarks in process, resource, management, and scientific outcomes. The efficacy outcomes of interest included changes in aerobic fitness, physical activity, walking, upper arm function, cognition, fatigue, and depressive symptoms. We hypothesized that 12 weeks of HIIT would result in improvements in aerobic capacity, walking, upper arm function, cognition, fatigue, and depression.
METHODS: A pre-post clinical trial design was applied. Participants (N = 16) were recruited and enrolled in the 12-week RSTEP HIIT program who met the following inclusion criteria: age ≥18 years, self-reported diagnosis of MS, Patient Determined Disability Steps scale score 3.0-7.0, relapse free in past 30 days, willing to visit a University Laboratory for study protocol, asymptomatic status for maximal exercise testing, physician approval, and a self-reported ability to speak, read, and understand English. Measures of efficacy outcomes of interest included Six Minute Walk Test (6MW), Timed 25 Foot Walk Test (T25FW), the Brief International Cognitive Assessment in MS (BICAMS), 9-hole peg test (9-HPT), Expanded Disability Status Scale (EDSS), Fatigue Severity Survey (FSS), Hospital Anxiety and Depression Scale (HADS), Godin Leisure Time Exercise Questionnaire (GLTEQ), Multiple Sclerosis Walking Scale-12 (MSWS-12). Participants completed a graded maximal exercise test for measuring aerobic fitness (VO2peak) and prescription of exercise throughout the intervention. All outcomes were measured at baseline, mid-point (6-weeks), and post-intervention (12-weeks). The intervention involved 12 weeks of supervised, individualized HIIT sessions two times per week using RSTEP. The individual HIIT sessions included 10 cycles of 60 s intervals at the work rate associated with 90 % VO2peak followed by 60 s of active recovery intervals, totaling 20 minutes plus 5-minute warm-up and cool-down periods. Process, resources, management, and scientific feasibility outcomes were examined using descriptive statistics, percentage, and frequency analyses. The efficacy of the intervention was assessed using a 1-factor (Time), repeated measure analysis of variance to identify significant changes over time.
RESULTS: Fourteen of 16 participants were retained throughout the full study period and adherence with prescribed exercise sessions was 97 %. Twenty-three staff were comprehensively trained across two sites. There was only one adverse event reported that did not impact participation in the study and overall mean satisfaction rating with the program among participants was 4.7/5. There were statistically significant changes in cognitive processing speed (p = 0.002), GLTEQ (p = 0.005), and MSWS-12 (p = 0.04), but not the other outcomes of fitness, arm function, and walking. Of note, there were large effect sizes noted for peak power output (d = 1.10) and FSS (d = 1.05) despite the lack of statistically significant changes CONCLUSION: Feasibility of a 12-week individualized RSTEP HIIT program was established and participants significantly improved on measures of cognition, physical activity, and walking.