A systematic review and meta-analysis examining whether changing ovarian sex steroid hormone levels influence cerebrovascular function

Sex differences in cerebrovascular disease rates indicate a possible role for ovarian sex steroid hormones in cerebrovascular function. To synthesise and identify knowledge gaps, a systematic review and meta-analysis was conducted to assess how ovarian sex steroid hormone changes across the lifespan affect cerebrovascular function in women. Three databases (EMBASE, MEDLINE and Web of Science) were systematically searched for studies on adult cerebrovascular function and ovarian sex steroid hormones. Forty-five studies met pre-defined inclusion criteria. Studied hormone groups included hormone replacement therapy (HRT; n = 17), pregnancy (n = 12), menstrual cycle (n = 7), menopause (n = 5), oral contraception (n = 2), and ovarian hyperstimulation (n = 2). Outcome measures included pulsatility index (PI), cerebral blood flow/velocity (CBF), resistance index (RI), cerebral autoregulation, and cerebrovascular reactivity. Meta-analysis was carried out on HRT studies. PI significantly decreased [−0.05, 95% CI: (−0.10, −0.01); p = 0.01] in post-menopausal women undergoing HRT compared to post-menopausal women who were not, though there was considerable heterogeneity (I2 = 96.8%). No effects of HRT were seen in CBF (p = 0.24) or RI (p = 0.77). This review indicates that HRT improves PI in post-menopausal women. However, there remains insufficient evidence to determine how changing ovarian sex steroid hormone levels affects cerebrovascular function in women during other hormonal phases (e.g., pregnancy, oral contraception)

Cool-water immersion reduces postexercise quadriceps femoris muscle perfusion more than cold-water immersion

Purpose The muscle perfusion response to postexercise cold-water immersion (CWI) is not well understood. We examined the effects of graded postexercise CWI upon global and regional quadriceps femoris muscle perfusion using positron emission tomography and [15O]H2O. Methods Using a matched-group design, 30 healthy men performed cycle ergometer exercise at 70% VO2peak to a core body temperature of 38°C, followed by either 10 min of CWI at 8°C, 22°C, or seated rest (control). Quadriceps muscle perfusion; thigh and calf cutaneous vascular conductance; intestinal, muscle, and local skin temperatures; thermal comfort; mean arterial pressure; and heart rate were assessed at preexercise, postexercise, and after CWI. Results Global quadriceps perfusion was reduced beyond the predefined minimal clinically relevant threshold (0.75 mL per 100 g·min-1) in 22°C water versus control (difference (95% confidence interval (CI)), -2.5 (-3.9 to -1.1) mL per 100 g·min-1). Clinically relevant decreases in muscle perfusion were observed in the rectus femoris (-2.0 (-3.0 to -1.0) mL per 100 g·min-1) and vastus lateralis (-3.5 (-4.9 to -2.0) mL per 100 g·min-1) in 8°C water, and in the vastus lateralis (-3.3 (-4.8 to -1.9) mL per 100 g·min-1) in 22°C water versus control. The mean effects for vastus intermedius and vastus medialis perfusion were not clinically relevant. Clinically relevant decreases in thigh and calf cutaneous vascular conductance were observed in both cooling conditions. Conclusions The present findings revealed that less noxious CWI (22°C) promoted clinically relevant postexercise decreases in global quadriceps muscle perfusion, whereas noxious cooling (8°C) elicited no effect

Cool-Water Immersion Reduces Post-Exercise Quadriceps Femoris Muscle Perfusion more than Cold-Water Immersion

Purpose: The muscle perfusion response to post-exercise cold water immersion (CWI) is not well understood. We examined the effects of graded post-exercise CWI upon global and regional quadriceps femoris muscle perfusion using positron emission tomography (PET) and [15O]H2O.Methods: Using a matched-group design, 30 healthy men performed cycle ergometer exercise at 70% V[Combining Dot Above]O2peak to a core body temperature of 38 °C, followed by either 10 min of CWI at 8 °C, 22 °C or seated rest (control). Quadriceps muscle perfusion, thigh and calf cutaneous vascular conductance (CVC), intestinal, muscle, and local skin temperatures, thermal comfort, mean arterial pressure, and heart rate were assessed at pre-, post-exercise and following CWI.Results: Global quadriceps perfusion was reduced beyond the pre-defined minimal clinically relevant threshold (0.75 mL·100 g·min-1) in 22 °C water versus control (difference [95% confidence interval (CI)]: -2.5 mL·100 g·min-1 [-3.9 to -1.1]). Clinically relevant decreases in muscle perfusion were observed in the rectus femoris (-2.0 mL·100 g·min-1 [-3.0 to -1.0]) and vastus lateralis (VL; -3.5 mL·100 g·min-1 [-4.9 to -2.0]) in 8 °C water, and in the vastus lateralis (-3.3 mL·100 g·min-1 [-4.8 to -1.9]) in 22 °C water versus control. The mean effects for vastus intermedius and vastus medialis perfusion were not clinically relevant. Clinically relevant decreases in thigh and calf CVC were observed in both cooling conditions.Conclusions: The present findings revealed that less noxious CWI (22 °C) promoted clinically relevant post-exercise decreases in global quadriceps muscle perfusion whereas noxious cooling (8 °C) elicited no effect.</p

Endurance exercise training enhances cutaneous microvascular reactivity in post-menopausal women

Objective To compare cutaneous microvascular reactivity between untrained young and post-menopausal women, and assess the effects of 48 weeks of endurance exercise training on cutaneous microvascular reactivity in post-menopausal women. Methods Twenty post-menopausal and 12 young women completed this study. Using laser-Doppler flowmetry, an index of skin blood flow was measured on the forearm at rest, during post-occlusive reactive hyperaemia (PORH), and during localised heating to 42 °C. Cutaneous vascular conductance (CVC) was calculated as the ratio of laser-Doppler flow to mean arterial pressure (in AU mm Hg−1). For the post-menopausal women, this assessment was also performed after 6, 12, 24, 36, and 48 weeks of endurance exercise training. Results PORH and maximum CVC responses were depressed in untrained post-menopausal women compared with young controls (P ≤ 0.011 for all methods of data expression). PORH was increased (P 0.05). Conclusion Cutaneous microvascular reactivity is reduced in post-menopausal women compared to young controls and increased to similar levels after 24–36 weeks of mild-to-moderate endurance exercise. Highlights ► Cutaneous vascular function was depressed in sedentary post-menopausal women. ► 24–36 weeks of aerobic exercise training restored cutaneous vascular function. ► Changes in vascular function correlated with changes in cardiopulmonary fitness

Acute β-Adrenergic Overload Produces Myocyte Damage through Calcium Leakage from the Ryanodine Receptor 2 but Spares Cardiac Stem Cells

A hyperadrenergic state is a seminal aspect of chronic heart failure. Also, “Takotsubo stress cardiomyopathy,” is associated with increased plasma catecholamine levels. The mechanisms of myocyte damage secondary to excess catecholamine exposure as well as the consequence of this neurohumoral burst on cardiac stem cells (CSCs) are unknown. Cardiomyocytes and CSCs were exposed to high doses of isoproterenol (ISO), in vivo and in vitro. Male Wistar rats received a single injection of ISO (5 mg kg(-1)) and were sacrificed 1, 3, and 6 days later. In comparison with controls, LV function was impaired in rats 1 day after ISO and started to improve at 3 days. The fraction of dead myocytes peaked 1 day after ISO and decreased thereafter. ISO administration resulted in significant ryanodine receptor 2 (RyR2) hyperphosphorylation and RyR2-calstabin dissociation. JTV519, a RyR2 stabilizer, prevented the ISO-induced death of adult myocytes in vitro. In contrast, CSCs were resistant to the acute neurohumoral overload. Indeed, CSCs expressed a decreased and inverted complement of β(1)/β(2)-adrenoreceptors and absence of RyR2, which may explain their survival to ISO insult. Thus, a single injection of ISO causes diffuse myocyte death through Ca(2+) leakage secondary to the acutely dysfunctional RyR2. CSCs are resistant to the noxious effects of an acute hyperadrenergic state and through their activation participate in the response to the ISO-induced myocardial injury. The latter could contribute to the ability of the myocardium to rapidly recover from acute hyperadrenergic damage

Monitoring athlete training loads: Consensus statement

Monitoring the load placed on athletes in both training and competition has become a very hot topic in sport science. Both scientists and coaches routinely monitor training loads using multidisciplinary approaches, and the pursuit of the best methodologies to capture and interpret data has produced an exponential increase in empirical and applied research. Indeed, the field has developed with such speed in recent years that it has given rise to industries aimed at developing new and novel paradigms to allow us to precisely quantify the internal and external loads placed on athletes and to help protect them from injury and ill health. In February 2016, a conference on 'Monitoring Athlete Training Loads-The Hows and the Whys' was convened in Doha, Qatar, which brought together experts from around the world to share their applied research and contemporary practices in this rapidly growing field and also to investigate where it may branch to in the future. This consensus statement brings together the key findings and recommendations from this conference in a shared conceptual framework for use by coaches, sport-science and-medicine staff, and other related professionals who have an interest in monitoring athlete training loads and serves to provide an outline on what athlete-load monitoring is and how it is being applied in research and practice, why load monitoring is important and what the underlying rationale and prospective goals of monitoring are, and where athlete-load monitoring is heading in the future

Interval exercise, but not endurance exercise, prevents endothelial ischemia-reperfusion injury in healthy subjects

Endothelial ischemia-reperfusion (I/R) injury importantly contributes to the poor prognosis during ischemic (myocardial) events. Preconditioning, i.e., repeated exposure to short periods of ischemia, effectively reduces endothelial I/R injury. In the present study, we examined the hypothesis that exercise has preconditioning effects on endothelial I/R injury. Therefore, we studied whether an acute bout of endurance or interval exercise is able to protect against endothelial I/R injury. In 17 healthy young subjects, we examined changes in brachial artery endothelial function using flow-mediated dilation (FMD) before and after a bout of high-intensity interval exercise, moderate-intensity endurance exercise, or a control intervention. Subsequently, I/R injury was induced by inflation of a blood pressure cuff around the upper arm to 220 mmHg for 20 min and 20 min of reperfusion followed by another FMD measurement. Near-infrared spectrometry was used to examine local tissue oxygenation during exercise. No differences in brachial artery FMD were found at baseline for the three conditions. I/R induced a significant decline in FMD (7.1 ± 2.3 to 4.3 ± 2.3, P < 0.001). When preceded by the interval exercise bout, no change in FMD was present after I/R (7.7 ± 3.1 to 7.2 ± 3.1, P = 0.56), whereas the decrease in FMD after I/R could not be prevented by the endurance exercise bout (7.8 ± 3.1 to 3.8 ± 1.7, P < 0.001). In conclusion, a single bout of lower limb interval exercise, but not moderate-intensity endurance exercise, effectively prevents brachial artery endothelial I/R injury. This indicates the presence of a remote preconditioning effect of exercise, which is selectively present after short-term interval but not continuous exercise in healthy young subjects

Seasonal reduction in physical activity and flow-mediated dilation in children

Purpose: Cardiovascular disease is a process that has its origins in childhood. Endothelial dysfunction is the earliest detectable manifestation of cardiovascular disease. This study aimed to assess the impact of seasonal changes in physical activity (PA) and body composition on conduit artery endothelial function in children. Method: We studied 116 children (70 girls aged 10.7 &plusmn; 0.3 yr and 46 boys aged 10.7 &plusmn; 0.3 yr) on two occasions; in the northern summer (June) and late autumn (November). We assessed flow-mediated dilation (FMD) using high-resolution Doppler ultrasound. Body composition was measured by dual-energy x-ray absorptiometry. PA was assessed using accelerometry. Results: FMD (10.0% &plusmn; 4.3% to 7.9% &plusmn; 3.9%, P &lt; 0.001) and PA (94.1 &plusmn; 34.8 to 77.8 &plusmn; 33.7 min&middot;d-1, P &lt; 0.01) decreased, while percentage body fat increased (27.6% &plusmn; 6.8% to 28.0% &plusmn; 6.6%, P &lt; 0.001) between summer and autumn. Decreases in FMD correlated with decreases in high-intensity PA (r = 0.23, P = 0.04), and change in high-intensity PA was the only predictor of change in FMD. No relationships were evident between changes in body composition and FMD. Conclusions: Vascular function decreased between summer and autumn in this cohort. There were no relationships between change in FMD and changes in body composition or low/moderate-intensity PA. The associations between FMD and high-intensity PA suggests that future interventions should encourage this form of behavior, particularly at the times of year associated with lower PA.<br /