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Physical inactivity increases cardiometabolic risk through a variety of mechanisms, among which alterations of immunological, metabolic, and autonomic control systems may play a pivotal role. Physical inactivity is frequently associated with other factors that may further worsen prognosis. The association between physical inactivity and hypoxia is particularly interesting and characterizes several conditions—whether physiological (e.g., residing or trekking at high altitude and space flights) or pathological (e.g., chronic cardiopulmonary diseases and COVID-19). In this randomized intervention study, we investigated the combined effects of physical inactivity and hypoxia on autonomic control in eleven healthy and physically active male volunteers, both at baseline (ambulatory) conditions and, in a randomized order, hypoxic ambulatory, hypoxic bedrest, and normoxic bedrest (i.e., a simple experimental model of physical inactivity). Autoregressive spectral analysis of cardiovascular variabilities was employed to assess cardiac autonomic control. Notably, we found hypoxia to be associated with an impairment of cardiac autonomic control, especially when combined with bedrest. In particular, we observed an impairment of indices of baroreflex control, a reduction in the marker of prevalent vagal control to the SA node, and an increase in the marker of sympathetic control to vasculature. [ABSTRACT FROM AUTHOR]

Introduction: Aerobic fitness seems to provide extra protection to the cardiovascular system beyond changing the traditional risk factors, a phenomenon referred to as the risk factor gap model. Aerobic fitness may possibly lead to improved autonomic regulation. The Task Force of the American Heart Association supports a national campaign to reach specific cardiovascular health goals considering various metrics, including recommended physical activity (PA) volumes. It may be clinically relevant to assess whether autonomic remodeling occurs in those who adhere to the PA recommendations. Methods: We studied 39 healthy subjects (22 males and 17 females), subdivided into two groups, according to whether they were meeting or not meeting PA recommendations (150 min/week of moderate aerobic activity, or 75 min/week of vigorous aerobic activity, or a combination of both). For each group, we evaluated aerobic capacity (VO Peak), body composition (Fat Mass) and autonomic nervous system profile, by way of mono and bivariate spectral analysis of cardiovascular beat by beat variability. Results: Subjects following PA recommendations show higher RR period, higher RR variance, greater absolute power of the respiratory component of RR variability (HF) and higher index alpha (a measure of spontaneous baroreflex). Moreover, as expected, the group that was meeting or exceeding current PA recommendations had higher VO peak, less fat mass and greater weekly energy expenditure. Conclusion: Data show that subjects meeting current PA recommendations present a phenotype suggestive of enhanced parasympathetic drive to the SA node. This finding is compatible with the hypothesis that a more favorable autonomic profile is part of the mechanisms of the risk factor gap. [ABSTRACT FROM AUTHOR]

The increased cardiometabolic risk observed in breast cancer survivors (BCS) is due to multiple mechanisms: Hormonal and immunological dysfunction are well-identified ones, while cardiac autonomic regulation (CAR) is less recognized but may play a new complementary role particularly relevant when considering conditions and behaviors associated with a better prognosis in BCS, such as physical training. This observational study investigated a group of consecutive (172) BCS subdivided in two groups: those who reached the physical activity goals above 600 (MET·min/week) and those who did not. We assessed CAR by autoregressive spectral analysis of cardiovascular variabilities (considering in particular the unitary autonomic nervous system index—ANSI), body mass composition, stress perception and lifestyle in order to verify possible differences due to execution of physical activity. Subjects who spontaneously met physical activity recommendations presented a better autonomic, metabolic and psychological profile compared to those who did not. Lower physical activity volume, poor metabolic parameters, increased stress and fatigue perception may cluster together, leading to worsened CAR. This control mechanism may play a complementary role in determining the increased cardiometabolic risk observed in BCS. Furthermore, it may also explain, albeit in part, the better prognosis observed in patients following interventions aiming to improve the sympathetic–parasympathetic balance, such as physical training, using a personalized medicine approach. [ABSTRACT FROM AUTHOR]

Overweight (OW) and obesity in children are important forerunners of cardiovascular risk, possibly through autonomic nervous system (ANS) dysregulation, while physical exercise exerts a beneficial influence. In this observational study we hypothesise that OW might influence ANS profile even in a population performing high volume of supervised exercise. We study 103 young soccer players, homogeneous in terms of gender (all male), cultural background, school, age (11.2±1 years) and exercise routine, since they all belong to the same soccer club, thus guaranteeing equality of supervised training and similar levels of competitiveness. ANS is evaluated by autoregressive spectral analysis of heart rate and systolic arterial pressure (SAP) variabilities. We estimate also the accumulated weekly Metabolic Equivalents and time spent in sedentary activities. We subdivide the entire population in two subgroups (normal weight and OW) based on the International Obesity Task Force criteria. In OW soccer players (10.7% of total group) we observe an altered profile of autonomic cardiovascular regulation, characterised by higher values of SAP (113±4 vs 100±1 mm Hg, 39.7±3 vs 66.2±10%), higher Low Frequency variability power of SAP (an index of vasomotor sympathetic regulation) (12±3 vs 4.5 mm Hg2) and smaller spontaneous baroreflex gain (an index of cardiac vagal regulation) (19±3 vs 33 ±3 ms/mm Hg) (all ( p<0.02)). Moreover Correlation analysis on the entire study population shows a significant link between anthropometric and autonomic indices. These data show that OW is associated to a clear autonomic impairment even in children subjected to an intense aerobic training. [ABSTRACT FROM AUTHOR]