Home exercise reduces cardiometabolic disease risk

Abstract

Obesity and a sedentary lifestyle are major contributors to poor metabolic and vascular health. As such, there has been a focus towards understanding the mechanisms underlying improvements in health related to physical activity. However, there remains a need for strategies that encourage patients to perform exercise independently and outside of the laboratory-supervised research setting. Investigations into skeletal muscle microvasculature function can provide insight into the links between cardiovascular and metabolic health. Increased nitric oxide (NO) production via endothelial NO synthase (eNOS) promotes muscle capillary recruitment to increase insulin-stimulated glucose uptake (Vincent et al. 2004). However, the levels of bioavailable NO are reduced in obesity due to quenching by oxidants, such as superoxide. NADPH oxidase (NOX) complexes are predominant sources of superoxide in the endothelium of obese individuals; therefore, the relative activation of eNOS versus NOX may provide an indication of microvascular function. In a recent issue of The Journal of Physiology, Scott et al. (2019) investigated whether home-based exercise can mitigate insulin resistance and vascular dysfunction while eliminating potential barriers of exercise adherence, such as access to facilities. Thirty-two males and females (age 36 ± 10 years) with an elevated risk of developing cardiovascular disease (body mass index 34.3 ± 5 kg/m; V̇O2peak 24.6 5.7 ml/kg/min) performed 12 weeks of exercise training under one of the following conditions: home-based high-intensity interval training (Home-HIT; n = 9), laboratory-based supervised HIT (Lab-HIT; n = 10) or home-based moderate-intensity continuous training (Home-MICT; n = 13). The participants who performed home-based exercise were ‘virtually supervised’ using a heart rate monitor, and instructed to achieve 80% or 65% of predicted heart rate maximum (HRmax 220 – age) during the intervals or continuous exercise, respectively. The home-based and laboratory-supervised HIT exercise sessions consisted of 1-min bouts of exercise interspersed with 1 min of rest. The Home-MICT group was instructed to perform continuous exercise of either swimming, cycling or walking/running. Participants in each group trained three times per week. To monitor adherence to exercise prescription, HR data obtained from the HR monitors were automatically uploaded to a cloud storage site (www.flow.polar.com) after each session. Endothelial function and aortic stiffness were assessed via flow-mediated dilatation (FMD) and pulse wave velocity (PWV), respectively. Insulin sensitivity was measured using an oral glucose tolerance test (OGTT). Lastly, a resting muscle biopsy was collected to measure markers of metabolic and vascular function via immunofluorescence. The primary finding was that the improvements in endothelium-dependent dilatation, aortic stiffness and insulin sensitivity were comparable between home-based exercise groups and laboratory-supervised exercise. In addition, the improvements in skeletal muscle microvascular function were similar, regardless of the exercise group. Notably, participants in each group also experienced concomitant improvements in V̇O2peak. The findings from this study suggest that performing home-based exercise of high or moderate intensity are effective strategies to reduce the risk of developing cardiometabolic disease. Given that the feasibility and practicality of HIT in obese populations have been challenged, Scott et al. (2019) demonstrate that performing HIT at home elicits similar improvements as compared to performing HIT in a laboratory-supervised environment.