Home‐Based High‐Intensity Interval Training Improves Muscle Capillarisation and eNOS/NAD(P)Hoxidase Protein Ratio in Obese Individuals with Elevated Cardiovascular Disease Risk

Abstract

ObjectivesThe vast majority of people undertake too little exercise to maintain good health suggesting novel strategies are needed to increase physical activity. Existing high‐intensity interval training (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. To combat the traditional exercise barriers, our laboratory has developed a novel home‐based HIT (Home‐HIT) programme that can be performed without equipment in a place of the participant's choosing using simple on‐the‐spot bodyweight exercises. This study aimed to investigate the effect of a 12‐week Home‐HT intervention in obese individuals with elevated cardiovascular disease (CVD) risk on skeletal muscle capillarisation, muscle microvascular eNOS/NAD(P)Hoxidase ratio, flow‐mediated dilation (FMD) and aortic pulse wave velocity (PWV). Comparisons were made with home‐based moderate‐intensity continuous training (Home‐MICT) and supervised laboratory‐based low‐volume HIT (Lab‐HIT) as control groups.Methods32 Sedentary obese adults with at least 3 additional CVD risk factors (age 36±2 years; BMI 34.3±0.8 kg·m−2; VO2peak 24.6±1.0 ml·kg−1·min−1) were allocated to 12 weeks of Home‐HIT (n=9), Home‐MICT (n=13) or Lab‐HIT (n=10). Muscle biopsies were taken pre‐ and posttraining to assess specifically in the endothelial layer of muscle arterioles and capillaries the protein content of eNOS, phospho‐eNOS ser1177, NOX2 and p47phox, and various capillarisation measures using quantitative immunofluorescence microscopy. Changes in VO2peak, insulin sensitivity, FMD and aortic PWV were also assessed.ResultsTraining increased VO2peak (P<0.001), whole‐body insulin sensitivity (P=0.033) and FMD (P<0.001), while aortic PWV decreased (P<0.001) in all 3 groups. Immunofluorescence microscopy revealed comparable increases in total eNOS content in terminal arterioles and capillaries (P<0.001) in the 3 conditions. There was no change in phospho‐eNOS ser1177 (arterioles P=0.802; capillaries P=0.311), but phospo‐eNOS ser1177/eNOS ratio significantly decreased following training in arterioles and capillaries (P<0.001). Training decreased NOX2 content (arterioles P<0.001; capillaries P<0.001), but there was no change in p47phox content (arterioles P=0.101; capillaries P=0.345). All measures of capillarisation increased (P<0.05). There were no differences in any variables between groups.ConclusionsThis study shows that 12 weeks of Home‐HIT, Home‐MICT and Lab‐HIT lead to skeletal muscle microvascular adaptations that underpin the functional improvements in VO2peak and insulin sensitivity. Importantly, Home‐HIT represents an alternative to traditional training methods that removes the major exercise barriers. This suggests that Home‐HIT is an effective strategy to improve public health in the obese population most in need.Support or Funding InformationThe Physiological SocietyThis abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.