Home‐hit improves muscle capillarisation and eNOS/NAD(P)Hoxidase protein ratio in obese individuals with elevated cardiovascular disease risk

Abstract

This study investigated the effect of a novel virtually supervised home-based high-intensity interval training (HIT) (Home-HIT) intervention in obese individuals with elevated cardiovascular disease (CVD) risk on capillarisation and muscle microvascular eNOS/NAD(P)Hoxidase ratio. Thirty-two adults with elevated CVD risk (age 36 ± 10 years; body mass index 34.3 ± 5 kg m^-2 ; <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mover><mml:mi>V</mml:mi><mml:mo>̇</mml:mo></mml:mover><mml:mrow><mml:msub><mml:mi>O</mml:mi><mml:mn>2</mml:mn></mml:msub><mml:mi>peak</mml:mi></mml:mrow></mml:msub></mml:math> 24.6 ± 5.7 ml kg min^-1 ), completed one of three 12-week training programmes: Home-HIT (n = 9), laboratory-based supervised HIT (Lab-HIT; n = 10) or virtually supervised home-based moderate-intensity continuous training (Home-MICT; n = 13). Muscle biopsies were taken before and after training to assess changes in vascular enzymes, capillarisation, mitochondrial density, intramuscular triglyceride content and GLUT4 protein expression using quantitative immunofluorescence microscopy. Training increased <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mover><mml:mi>V</mml:mi><mml:mo>̇</mml:mo></mml:mover><mml:mrow><mml:msub><mml:mi>O</mml:mi><mml:mn>2</mml:mn></mml:msub><mml:mi>peak</mml:mi></mml:mrow></mml:msub></mml:math> (P < 0.001), whole-body insulin sensitivity (P = 0.033) and flow-mediated dilatation (P < 0.001), while aortic pulse wave velocity decreased (P < 0.001) in all three groups. Immunofluorescence microscopy revealed comparable increases in total eNOS content in terminal arterioles and capillaries (P < 0.001) in the three conditions. There was no change in eNOS ser¹¹⁷⁷ phosphorylation (arterioles P = 0.802; capillaries P = 0.311), but eNOS ser¹¹⁷⁷ /eNOS content ratio decreased significantly 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 p47^phox content (arterioles P = 0.101; capillaries P = 0.345). All measures of capillarisation increased (P < 0.05). There were no between-group differences. Despite having no direct supervision during exercise, virtually supervised Home-HIT resulted in comparable structural and endothelial enzymatic changes in the skeletal muscle microvessels to the traditional training methods. We provide strong evidence that Home-HIT is an effective novel strategy to remove barriers to exercise and improve health in an obese population at risk of CVD.