Exercise Training and Respiratory Muscle Training in Individuals With Metabolic Syndrome(METS)

Metabolic syndrome (METS) is a systemic endocrinopathy characterized by the presence of risk factors such as abdominal obesity, glucose intolerance or diabetes mellitus, atherogenic dyslipidemia, hypertension, and a persistent proinflammatory profile. According to the International Diabetes Federation (IDF) definition of METS, almost 20-25% of the adult world population has METS, and people with METS are at risk of heart attack, stroke, type 2 diabetes (T2D), all-cause and cardiovascular death (approximately three times higher). In addition, modifiable risk factors such as physical inactivity, diet, and sedentary behavior have all been associated with increased prevalence of METS. Increasing incidence of METS, increase in morbidity and mortality necessitated the implementation of preventive strategies and the implementation of pharmacological and non-pharmacological treatments.

Studies in the literature have shown that vagal tone decreases and sympathetic tone increases in patients with METS. At the same time, impaired baroreflex sensitivity and decreased heart rate variability are observed in these patients. Changes in autonomic modulation cause the release of some bioactive molecules by affecting the endocrine and immune systems. In this case, increased sympathetic autonomic tone creates a cardiometabolic risk. In adults with METS, autonomic dysfunction appears to be more prominent in women than in men. Autonomic functions are impaired due to changes such as loss of lean body mass, increase in fat mass, increase in body mass, redistribution of fat from the periphery to the middle parts of the body, especially in postmenopausal women. As a result, increased blood pressure, impaired endothelial function, decreased glucose tolerance, and atherogenic changes in lipid and coagulation profiles can be observed. This increases the incidence of METS in postmenopausal women. Therefore, strategies to reduce the risk of metabolic syndrome have often been studied on women in the literature, and there is a need for studies involving men and new strategies.

Physical activity and exercise training are recommended as key prescriptions for the prevention and treatment of METS and low-grade chronic inflammation . Increase in physical exercise has been recommended for the prevention and primary treatment of cardiovascular disease (CVD) and METS because of the cardioprotective benefits associated with improved cardiorespiratory fitness (CRF). There are many studies showing that aerobic exercise provides significant improvements in waist circumference, fasting glucose, high-density lipoprotein cholesterol (HDL-C), TG, systolic and diastolic blood pressure (SBP-DBP), and cardiorespiratory fitness on METS parameters . However, although the beneficial effects of physical activity are known, only half of the population adheres to the 150 minutes of moderate-intensity physical activity per week recommendation. It has been shown that one of the main barriers to reaping health benefits and being more active is "lack of time". High-intensity interval training (HIIT) is a type of training that uses near-maximal intensities in short-term sessions. HIIT has been used to improve compliance because it requires less time to treat patients with cardiometabolic disease. Compared to continuous aerobic exercise, this type of training is an effective alternative to improve maximum oxygen consumption (VO2max), blood pressure, heart function, glucose and lipid metabolism, and markers of oxidative stress and inflammation . However, it has been seen that there are not enough studies on HIIT effectiveness on METS parameters in the literature. Therefore, researchers aimed to show the effects of HIIT training applied together with respiratory muscle training on METS parameters in patients with METS.

It has shown the beneficial effects of exercise training as well as inspiratory muscle training (IME) on autonomic function in patients with hypertension and heart disease . In a study, it was shown that 7-day inspiratory muscle training improved respiratory muscle functions and cardiac autonomic functions in postmenopausal women . As a result of this study, inspiratory muscle training has been proposed as a nonpharmacological strategy to improve autonomic modulation and reduce risk factors in individuals with METS, but further studies are required to confirm the long-term effects or effects of inspiratory muscle training in addition to classical exercise training protocols such as aerobic, resistance or combined training. are needed.

In a study conducted in healthy and middle-aged men and postmenopausal women in 2021, it was proven that high resistance inspiratory muscle strength training can improve blood pressure control and vascular endothelial function, and reduce the risk of cardiovascular disease and other clinical disorders. In this study, researchers presented the first evidence that inspiratory muscle strength training increases NO bioavailability, decreases systemic inflammation, and causes potentially beneficial changes in the plasma metabolome by increasing endothelial NO synthase activation and decreasing oxidative stress. In conclusion, it has been shown that inspiratory muscle strength training can be used as a promising lifestyle intervention to improve cardiovascular function and reduce the risk of other clinical disorders .

Since the long-term effects of respiratory muscle training in individuals with METS have not been examined in the literature; researchers planned this study to examine the effects of inspiratory muscle strength training added to aerobic exercise training (HIIT) on physical fitness, respiratory functions and METS parameters in individuals with METS.