Effectiveness of high intensity interval training on cardiorespiratory fitness and endothelial function in type 2 diabetes: A systematic review

Hormonal and Glycemic Responses During and After Constant- and Alternating-Intensity Exercise

Background/Objectives: Glucose metabolism and hormonal responses are largely affected by exercise intensity, which exhibits an alternating pattern in many sports activities. The aim of this study was to investigate and compare glycemic and hormonal responses during and after exercise of constant (CON) and alternating (ALT) intensity with the same duration and total work. Methods: Ten healthy male volunteers performed two, 60 min cycling exercise bouts in random order: the ALT bout, where exercise intensity alternated between 46.5 ± 1.9% of VO2max for 40 s and 120% of VO2max for 20 s, so the mean intensity was at 105% of the lactate threshold (LT), and the CON exercise bout, where the intensity was constant at 105% of LT (70 ± 4.7% of VO2max). Results: No significant differences were observed in blood glucose concentrations between the two exercise protocols (p = 0.22) or over time at any time point measured, i.e., before, at 30 and 60 min of each exercise bout, and 60 min post-exercise (p > 0.05). Circulating insulin levels decreased significantly over time in both protocols (p < 0.01 and p < 0.05 in ALT and CON, respectively); nevertheless, they did not differ between the exercise protocols (p = 0.45). Similarly, there were no significant differences in serum leptin and prolactin levels between the two protocols (p = 0.77 and p = 0.80 in ALT and CON, respectively); however, circulating levels of leptin decreased at 30 and 60 min of exercise only in CON (p < 0.05) and those of prolactin at 60 min of exercise only in ALT (p < 0.05) compared to pre-exercise values. Conclusions: Cycling exercise of constant or alternating moderate intensity (~70% of VO2max) with the same duration induces similar glycemic but differential over time hormonal responses in healthy males.

Exercise to Prevent Accelerated Vascular Aging in People Living With HIV

Given advances in antiretroviral therapy, the mortality rate for HIV infection has dropped considerably over recent decades. However, people living with HIV (PLWH) experience longer life spans coupled with persistent immune activation despite viral suppression and potential toxicity from long-term antiretroviral therapy use. Consequently, PLWH face a cardiovascular disease (CVD) risk more than twice that of the general population, making it the leading cause of death among this group. Here, we briefly review the epidemiology of CVD in PLWH highlighting disparities at the intersections of sex and gender, age, race/ethnicity, and the contributions of social determinants of health and psychosocial stress to increased CVD risk among individuals with marginalized identities. We then overview the pathophysiology of HIV and discuss the primary factors implicated as contributors to CVD risk among PLWH on antiretroviral therapy. Subsequently, we highlight the functional evidence of premature vascular dysfunction as an early pathophysiological determinant of CVD risk among PLWH, discuss several mechanisms underlying premature vascular dysfunction in PLWH, and synthesize current research on the pathophysiological mechanisms underlying accelerated vascular aging in PLWH, focusing on immune activation, chronic inflammation, and oxidative stress. We consider understudied aspects such as HIV-related changes to the gut microbiome and psychosocial stress, which may serve as mechanisms through which exercise can abrogate accelerated vascular aging. Emphasizing the significance of exercise, we review various modalities and their impacts on vascular health, proposing a holistic approach to managing CVD risks in PLWH. The discussion extends to critical future study areas related to vascular aging, CVD, and the efficacy of exercise interventions, with a call for more inclusive research that considers the diversity of the PLWH population.

The physiologic benefits of optimizing cardiorespiratory fitness and physical activity - From the cell to systems level in a post-pandemic world

Cardiovascular (CV) disease (CVD) is a leading cause of premature death and hospitalization which places a significant strain on health services and economies around the World. Evidence from decades of empirical and observational research demonstrates clear associations between physical activity (PA) and cardiorespiratory fitness (CRF) which can offset the risk of mortality and increase life expectancy and the quality of life in patients. Whilst well documented, the narrative of increased CRF remained pertinent during the coronavirus disease 2019 (COVID-19) pandemic, where individuals with lower levels of CRF had more than double the risk of dying from COVID-19 compared to those with a moderate or high CRF. The need to better understand the mechanisms associated with COVID-19 and those that continue to be affected with persistent symptoms following infection (Long COVID), and CV health is key if we are to be able to effectively target the use of CRF and PA to improve the lives of those suffering its afflictions. Whilst there is a long way to go to optimise PA and CRF for improved health at a population level, particularly in a post-pandemic world, increasing the understanding using a cellular-to-systems approach, we hope to provide further insight into the benefits of engaging in PA.

Preventive and Therapeutic Effects of Silybum marianum Seed Extract Rich in Silydianin and Silychristin in a Rat Model of Metabolic Syndrome

Metabolic syndrome (MetS) has become an increasing global health problem, which leads to cardiovascular diseases and type 2 diabetes. Silybum marianum extracts have been reported to possess several biological activities. In this study, an ethyl acetate extract prepared from S. marianum seeds of the Iraqi Kurdistan region was analyzed to identify its chemical constituents. Subsequently, its potential for the prevention and treatment of MetS was studied in a rat model induced by a high-fat/high-fructose diet (HFD/F). Silydianin and silychristin were the most abundant flavonolignan constituents (39.4%) identified in the S. marianum extract (SMEE). HFD/F-induced rats treated with SMEE exhibited preventive effects including reduced serum triglyceride levels (TG), decreased glucose levels in an oral glucose tolerance test (p < 0.001), attenuated weight gain, and reduced blood pressure compared to the untreated control group. Therapeutic application of SMEE after inducing MetS led to lowering of TG (p < 0.001) and glucose levels, in addition to reducing weight gain and normalizing blood pressure (p < 0.005). Thus, S. marianum extract rich in silydianin and silychristin may be useful for preventing and attenuating MetS, and further research and clinical trials are warranted.