Effects of a 12-Week Home-Based High-Intensity Interval Training Programme in Obese Individuals With Elevated Cardiovascular Disease Risk: A Pilot Study

The applicability of current high intensity interval training (HIT) protocols to the sedentary obese population has been disputed by public health experts. Existing HIT interventions have been successful only under optimal conditions with high levels of supervision and specialised equipment, creating further barriers to exercise in those most in need. We aimed to eliminate many of these barriers by modifying existing HIT protocols to create a new home-based HIT (Home-HIT) intervention tailored to individuals with low fitness and mobility. It was hypothesised that Home-HIT would 1) have high adherence to the prescribed exercise intensity (compliance) and 2) improve markers of cardiovascular disease (CVD) risk. 32 Obese adults with at least 3 additional CVD risk factors (age 36±2 y; BMI 34.3±0.8 kg∙m-2; VO2peak 24.6±1.0 ml∙kg∙min-1), completed one of three 12-week training programmes 3x/week: Home-HIT (n=9); Laboratory-based supervised HIT (Lab-HIT; n=10) or home-based moderate intensity continuous training (Home-MICT; n=13). Adherence and compliance were monitored online in almost "real time" using a heart rate (HR) monitor and mobile app. The Home-HIT group completed 4 progressing to 8 1min intervals interspersed with 1min of rest in an unsupervised place of their choosing. The intervals were composed of simple bodyweight exercises that required no equipment. Changes in VO2peak, insulin sensitivity, body composition, flow-mediated dilation (FMD) and aortic pulse wave velocity (PWV) were assessed. Muscle biopsies were taken to assess changes in capillarisation, mitochondrial density, intramuscular triglyceride (IMTG) content and eNOS and GLUT4 protein expression using quantitative immunofluorescence microscopy.