Proof of concept: can REHIT offset unfavorable cardiometabolic profiles in a sedentary disabled population?

Introduction: Reduced exertion high intensity training (REHIT), is a variation of high intensity interval training (HIIT) utilizing a minimal amount of exercise and exertion to elicit metabolic health benefits, including reduced blood pressure, improved lipid profile, improved glucose sensitivity, reduced waist circumference, and reduced BMI. The aim of this proof of concept study was twofold; (1) to investigate the effects of interrupting prolonged sedentary bouts with a daily REHIT upper-body session on cardiometabolic risk factors in individuals with mobility disabilities and, (2) to determine the feasibility of implementing a REHIT program in this population. Methods: Two females (56±2.2 years) participated in this repeated measures experimental design study. The study occurred over two weeks. Week one was the control, subjects maintained their normal activity levels. During week two, subjects participated in a once-a-day, eight-minute, at-home, upper-body REHIT session with a light-medium resistance band. Cardiometabolic profiles were measured on days 1, 8, and 15. This study was not intended to identify significant, generalizable, health benefits due to the sample size, and instead explored the feasibility of the intervention as it may apply to a larger sample. Because this was a proof-of-concept study, with a small n, the data was analyzed descriptively. Results: Two trends in cardiovascular health biomarkers were found post-REHIT intervention: LDL decreased 15.5±0.5 mg/dL and TC decreased 16.5±2.5 mg/dL. There were no consistent trends in any of the other outcomes, including OGTT and MetS z-score. However, trends were noted in relation to total activity level. The greatest cardiometabolic profile benefits were observed during the most active week of the study. Distinct individual differences were noted. Two of the three feasibility criteria were met: Notably, progression criterion 1: Recruitment and retention rates were deemed unlikely to be feasible, most likely due to COVID-19. Progression criterion 2: The acceptability of the intervention did meet the criterion threshold and may be suitable in the current form for any related future studies. Progression criterion 3: Outcomes showed two positive trends in metabolic health but did not show any other trends. Conclusion: Two of the three criteria for progression to a full-scale study were met. Therefore, using REHIT in sedentary and disabled populations may be an effective intervention to increase energy expenditure and improve cardiometabolic health in these populations.