Impact of the menstrual cycle on peripheral vascular function in premenopausal women: systematic review and meta-analysis

CD4+ T Cells Expressing Viral Proteins Induce HIV-Associated Endothelial Dysfunction and Hypertension Through Interleukin 1α-Mediated Increases in Endothelial NADPH Oxidase 1

BACKGROUND

Although combination antiretroviral therapy has increased life expectancy in people living with HIV, it has led to a marked increase in the prevalence of hypertension, the cause of which is unknown. Despite combination antiretroviral therapy, HIV-derived proteins remain expressed and produced by CD4+ T lymphocytes in people living with HIV. However, their contribution to HIV-associated hypertension and impaired endothelium-dependent relaxation remains ill defined.

METHODS

Here, we tested the hypothesis that CD4+ T cells expressing viral proteins contribute to endothelial dysfunction and hypertension using the Tg26 mouse model of HIV that expresses 7 of the 9 HIV proteins under the long terminal repeat promoter. We used male and female mice, bone marrow transplantation (BMT), adoptive transfer of CD4+ T cells, and aorta specimen discarded from people living with HIV.

RESULTS

We reported that intact Tg26 mice and mice receiving BMT (Tg26→WT) or CD4+ T cells from Tg26 mice display impaired endothelium-dependent relaxation and hypertension. Conversely, BMT from WT mice into Tg26 mice, inhibition of T cell activation, and CD4+ T cell depletion restored endothelial function and blood pressure in Tg26 mice. Cytokine profiling revealed that Tg26 mice, Tg26→WT, and Tg26 CD4+ T cells consistently exhibit high interleukin 1α (IL-1α) levels with no significant increase in other cytokines, whereas BMT from WT mice into Tg26 mice reduced IL-1α levels. IL-1α neutralization reduced blood pressure and restored endothelial function in Tg26 mice. To investigate the role of CD4+ T cells and IL-1α in endothelial dysfunction, we developed an aorta-immune cell coculture system. Exposure of WT aortas to Tg26 CD4+ T cells impaired endothelium-dependent relaxation, which was blocked by IL-1α-neutralizing antibody. While investigating the mechanisms of endothelial dysfunction, we reported that Tg26 mice, Tg26→WT aorta exhibit high NADPH oxidase (NOX) 1 expression. IL-1α exposure increased NOX1 in human microvascular endothelial cells, and NOX1 blockade restored endothelial function in Tg26 and Tg26→WT arteries, whereas NOX1 deficiency protected against Tg26 BMT-induced impaired endothelium-dependent relaxation and hypertension. Aortas from people living with HIV exhibit high NOX1 levels, and exposure of human aorta to Tg26 T cells increased NOX1 expression.

CONCLUSIONS

We provide the first evidence that CD4+ T cells expressing HIV viral proteins induced hypertension through IL-1α-mediated increases in vascular NOX1, which impairs endothelial function in males and females.

Interactions of chronic stress exposure and stress appraisal on vascular endothelial function among young adults

We investigated the associations of ongoing, chronic stress exposure and stress appraisal on vascular endothelial function (VEF) in young adults. In 72 healthy young adults (74% female; age = 25 ± 1 yr), we assessed chronic stress exposure and appraisal with a measure that quantified chronic stress exposure and chronic stress appraisal related to eight specific stressors over the last year. Participants completed the perceived stress scale (PSS) as a measure of global, proximal stress appraisal. VEF was assessed using the brachial artery flow-mediated dilation technique. We examined relations among ongoing, chronic stress exposure and stress appraisal versus VEF adjusted for age and sex, and then assessed whether stress appraisal moderated the effect of chronic stress exposure on VEF. Chronic stress exposure (β = -0.24, P = 0.045), but not chronic stress appraisal (β = 0.07, P = 0.56) or perceived stress (β = -0.20, P = 0.11), was related to VEF. Perceived stress (P = 0.046), but not chronic stress appraisal (P = 0.54), moderated the association between chronic stress exposure and VEF. The effect of chronic stress exposure on VEF ceased to be significant at a PSS score of ∼22. Subsequent exploratory stratified analysis indicated that those with PSS ≥22 had increased exposure to adverse childhood experiences (+1.6 ± 0.6, P = 0.01), greater depressive symptoms (+10.2 ± 2.7, P < 0.001), and reduced psychological resilience (-7.6 ± 3.5, P = 0.036). Chronic stress exposure significantly predicts impaired VEF among young adults. Furthermore, this relation is influenced by proximal perceived stress, such that the association of chronic stress exposure on VEF may be obscured at high levels of proximal perceived stress.NEW & NOTEWORTHY Our findings indicate that ongoing chronic stress exposure over the last year is significantly associated with reduced vascular endothelial function among apparently healthy young adults. Our data provide important insights into the interplay of chronic stress exposure versus proximal perceived stress and may also support the hypothesis that young adults who are sensitized to stress may be particularly vulnerable to stress-related impairments in vascular endothelial function.

Cold pressor-induced sympathetic activation blunts the femoral but not carotid artery vascular responsiveness

Vascular responsiveness due to passive leg movement (PLM) on the brain remains unknown. This study aimed to evaluate the effects of cold-induced sympathetic activation (CPT) on femoral and ipsilateral and contralateral carotid arteries' vascular responsiveness evoked by PLM. Thirteen participants (seven males and six females; age: 27.0 ± 2.3 years) undertook a randomized session in which PLM was performed on the right leg at rest and during CPT. Right femoral (fBF) and right (ipsilateral) and left (contralateral) carotid (cBF) blood flows were measured by ultrasounds, and heart hemodynamics were assessed via photoplethysmography and impedance cardiograph. Systolic arterial pressure (SAP) time series were used to infer sympathetic modulation to the vessels. Femoral (fVC) and carotid (cVC) vascular conductance (BF/MAP) were calculated. CPT evoked changes in PLM on cBF, fBF, and fVC (interaction and time effect). cBF peak and cBF and cVC area under the curve were higher in the contralateral carotid in the two interventions. Low-frequency power of SAP was higher in PLM-CPT than in PLM; all p < 0.05. These results suggest that the CPT-induced increases in sympathetic modulation attenuate the vascular responsiveness in the femoral, but not the carotid, arteries. Also, the contralateral carotid increased blood flow during PLM, regardless of the CPT.

Preservation of Vascular Endothelial Function in Late-Onset Postmenopausal Women

BACKGROUND

Postmenopausal women (PMW) who complete menopause at a late age (55+ years) have lower cardiovascular disease risk than PMW who complete menopause at a normal age (45-54 years). However, the influence of late-onset menopause on vascular endothelial dysfunction is unknown. Moreover, the mechanisms by which a later age at menopause may modulate endothelial function remain to be determined.

METHODS

We measured endothelial function (brachial artery flow-mediated dilation [FMDBA]) in age-matched late- and normal-onset PMW and a young premenopausal reference group. We determined mitochondrial reactive oxygen species (mitoROS)-related suppression of endothelial function (change in FMDBA with an acute dose of the mitochondria-targeted antioxidant MitoQ; ΔFMDBA, MTQ) in PMW. The effects of serum from late- and normal-onset PMW and premenopausal women on mitoROS bioactivity in human aortic endothelial cells in culture were assessed. Metabolomics analyses in combination with serum metabolite level normalization and human aortic endothelial cell serum exposure experiments were performed to identify the circulating factors contributing to the serum effects on endothelial cell mitoROS bioactivity.

RESULTS

FMDBA in PMW was lower than in premenopausal women. However, FMDBA was >50% higher in late- versus normal-onset PMW and positively related to age at menopause. ΔFMDBA, MTQ was >50% lower in late- versus normal-onset PMW. Serum from normal-onset PMW but not late-onset PMW induced higher mitoROS bioactivity in human aortic endothelial cells compared with serum from premenopausal women. MitoROS bioactivity was negatively related to FMDBA and age at menopause. Seventeen metabolites significantly differed between late- and normal-onset PMW; 15 were lipid specific; 8 were triglyceride derived. TG(16:0) was most strongly correlated with mitoROS bioactivity. Normalization of TG(16:0) concentrations in serum from premenopausal women and late-onset PMW to match serum levels in normal-onset PMW abrogated differences in mitoROS bioactivity in serum-treated human aortic endothelial cells.

CONCLUSIONS

Late-onset menopause is associated with preservation of endothelial function, which is mediated by lower mitoROS-associated oxidative stress. A more favorable profile of circulating lipid metabolites, specifically triglyceride-derived metabolites, contributes to lower endothelial cell mitoROS in late-onset PMW. These findings provide new insight into the possible mechanisms of reduced cardiovascular disease risk in late-onset menopause.

Doppler Ultrasound Assessment of Blood Flow Indices in Childbearing Age Women Across the Menstrual Cycle

Background and Objectives: This study investigates the effects of hormonal fluctuations during the menstrual cycle and oral contraceptive (OCP) cycles on peripheral vascular circulation in the lower limbs of healthy childbearing-age women across different phases of the menstrual cycle. Materials and Methods: Fourteen eumenorrheic non-oral contraceptive (non-OCP) users (mean age 28.9 ± 3.5 years; height 165.0 ± 5.8 cm; weight 66.8 ± 11.2 kg) were evaluated during the follicular and ovulatory phases. Fifteen monophasic oral contraceptive (OCP) users (mean age 26.4 ± 2.67 years; height 162.3 ± 8.1 cm; weight 62.0 ± 9.8 kg) were assessed during their placebo and active pill phases. Doppler recordings of the femoral and popliteal arteries were obtained, and standard Doppler indices (systolic/diastolic ratio, pulsatility index, and resistance index) were analyzed across the menstrual and OCP cycles. Results: There were no significant interactions in the standard Doppler indices for the popliteal and femoral arteries between the menstrual phases and user groups (p > 0.05). Additionally, no significant group effects were observed between non-OCP users and OCP users, nor were there significant phase effects in any of the Doppler index variables (p > 0.05). Conclusions: Peripheral vascular function remained stable across menstrual and OCP phases, suggesting minimal impact of hormonal fluctuations on blood flow characteristics in young, healthy females.

Changes in the reactive hyperemia index after continuous and interval exercise

INTRODUCTION

High-intensity interval exercise (HIIE) is more effective than moderate-intensity interval exercise (MICE) for improving macrovascular function (e.g., flow-mediated dilation), but less is known regarding the effect of HIIE on microvascular function. We used peripheral artery tonometry to measure the reactive hyperemia index (RHI) and examine the acute effects of HIIE and MICE on microvascular function.

METHODS

Ten healthy participants (50% men, age: 26 ± 5 years, mass: 75.6 ± 15.1 kg, height: 170 ± 10 cm, body mass index: 26.0 ± 3.1 kg∙m-2) performed single bouts of HIIE and MICE cycling on separate occasions. The MICE protocol was 20 min at 60% of maximum power output. The HIIE protocol was a 12-min warm up at 50% of maximum power output immediately followed by an 8-min Tabata protocol where participants alternated between cycling at ⩾ 100% max power (20 sec) and rest (10 sec). The RHI was measured before, immediately after, and 1 h after exercise and compared by two-way repeated measures analysis of variance (condition [MICE, HIIE] and time [pre-, post-, and 1-h postexercise]).

RESULTS

Compared to baseline, RHI increased 1 h after MICE only (p = 0.02). Heart rate was higher during MICE at 5 and 10 min (p = 0.02) and higher during HIIE at min 20 (p < 0.01).

CONCLUSION

Within a sample of healthy adults, the RHI was improved 1 h after a single session of MICE but not HIIE. Future research is needed to determine the significance of the differential effects of exercise regimens on the macro- and microvasculature.

Vascular health and exercise in females throughout the lifespan: Exploring puberty, pregnancy and menopause

This narrative review highlights the impact of exercise on vascular health in females over the lifespan with an emphasis on puberty, pregnancy and menopause. These events encompass substantial changes in sex hormone levels, particularly oestrogens and progesterone. They are also accompanied by distinct adaptations of the central, peripheral and cerebral vasculature. Regular exercise is an effective mechanism to reduce vascular risk in females of all ages, especially for those at higher risk for vascular disorders. However, there are large variabilities in the vascular adaptations to exercise in females that may be related to circulating sex hormone levels. In addition, exogenous hormones, such as oral contraceptives taken after puberty or hormonal replacement therapy taken to mitigate symptoms of menopause, may interact with exercise-induced changes in vascular function. We highlight how more research is needed to understand the optimal exercise interventions to promote vascular health in females across the lifespan, especially during times of hormonal transition.

The relationships between age, sex, and exercise intensity on cerebral artery hemodynamics during isometric handgrip exercise

Age and sex may alter the cerebral blood flow (CBF) responses to acute isometric exercise, via associated elevations in mean arterial pressure (MAP) and sympathetic activation. Our aim was to determine the relationships between age, sex, and exercise intensity on cerebrovascular responses to isometric handgrip exercise. In 78 healthy adults (18-80 yr, n = 42 females), cerebrovascular responses were assessed during 2-min isometric exercise bouts at three intensities [15, 30, 45% maximal voluntary contraction (MVC)]. Intracranial responses of the middle cerebral artery (MCA) and posterior cerebral artery (PCA) velocity (v) were measured using transcranial Doppler ultrasound. Extracranial responses of the internal carotid artery (ICA) and vertebral artery (VA) were assessed using Duplex ultrasound. Cardiopulmonary hemodynamic and neural parameters were measured throughout, including muscle sympathetic nerve activity, end-tidal carbon dioxide, and MAP. There were significant positive relationships between exercise intensity and the cerebral responses of the MCAv (P < 0.001) and PCAv (P = 0.005). There were no effects of intensity on ICA and VA responses (P > 0.05), despite intensity-dependent increases in MAP (P < 0.001). The increased MCAv response to exercise was blunted with advancing age (P = 0.01) with no influence of sex (P = 0.86). The present study provides data on age, sex, and intensity-specific relationships with intracranial and extracranial cerebrovascular responses to isometric exercise. Despite similar ICA, VA, and PCA responses, MCAv responses were attenuated with advancing age during handgrip exercise with no sex-dependent influence. Furthermore, intracranial responses were intensity dependent, whereas extracranial blood flow, shear-stress, and velocity responses were similarly increased at all intensities during handgrip exercise.NEW & NOTEWORTHY The influence of aging and sex on cerebral blood flow responses to isometric exercise are unknown. We observed intensity-dependent increases in velocity of the intracranial arteries, whereas the extracranial artery responses were similarly increased at all intensities during handgrip exercise in young and older individuals. Furthermore, we observed a blunted middle cerebral artery velocity response to handgrip exercise with advancing age, whereas the posterior circulation and extracranial responses were preserved across the lifespan in healthy individuals in males and females alike.

Vasculature of older females shows heterogeneity in the association between cardiovascular risk and vascular function

Although affecting both sexes, loss of sex hormones and consequently increased risk for cardiovascular disease (CVD) render particular features to vascular aging in females. More importantly, although the female's vasculature is more sensitive to CVD risk factors, CVD is often underdiagnosed in women. In the present study, we investigated vascular function in the arm and leg skeletal muscle microvasculature and conduit artery in young and older females. We also applied a mixed-effect regression analysis to examine the relationship between vascular function and CVD risk factors in women. We showed that the detrimental effects of age in conduit artery vascular function, as assessed by flow-mediated dilation (%FMD), were more evident in the lower limb (older, 2.6 ± 0.5 vs. young, 7.2 ± 0.9%; P = 0.0116) compared with the upper limb (older, 5.3 ± 0.5 vs. young, 7.3 ± 0.4%; P = 0.175). In addition, we demonstrate that CVD risk factors, mainly plasma lipid levels [very low-density lipoprotein cholesterol (VLDL-c): r2 = 0.415, P = 0.007; high-density lipoprotein cholesterol (HDL-c): r2 = 0.313, P = 0.024; triglycerides: r2 = 0.422, P = 0.006] and insulin sensitivity index [homeostasis model assessment of insulin resistance (HOMA-IR): r2 = 0.635, P < 0.001; QUICKI: r2 = 0.792, P < 0.001], were exclusively associated with upper limb skeletal muscle microvascular function in older females. In aggregate, our findings provide novel evidence that impairments in conduit artery function in older females are more pronounced in the lower limb vasculature compared with the upper limb. Also, we demonstrate that older women's upper limb microvasculature function may be more susceptible to the impact of CVD risk factors than lower limb microvasculature function and both limb's conduit arteries.NEW & NOTEWORTHY Even though the vasculature of older females has been suggested to be more sensitive to the detrimental effects of traditional cardiovascular risk factors, cardiovascular disease in women is often underdiagnosed. We show that aging-associated vascular dysfunction is more evident in the lower limb conduit arteries compared with the upper limb in older women. More importantly, we demonstrate that traditional cardiovascular risk factors were exclusively associated with upper limb skeletal muscle microvascular function in older females.

Cardiovascular, perceptual, and performance responses to single- vs. multi-chambered blood flow restriction cuffs

Introduction

This study aimed to investigate the impact of the blood flow restriction bladder type (single- [SC-BFR] vs. multi-chambered [MC-BFR]) on exercise performance, cardiovascular responses, and perceptual experiences with exercise sessions incorporating multiple sets to volitional failure in a randomized, crossover experimental design.

Methods

Twenty-seven healthy, physically active participants (age: 22.6 ± 5.7; weight: 74.3 ± 15.8 kg; height: 171.7 ± 7.7 cm; BMI: 25.0 ± 4.1 kg/m2; ∼93% reported regular resistance training within 6 months; 11 females) randomly performed exercise to failure (4× sets to failure, 20% 1RM, 1 min rest between sets) in each of three conditions: SC-BFR (using the Delfi Personalized Tourniquet Device inflated to 60% limb occlusion pressure), MC-BFR (using the B Strong Cuffs inflated to 300 mmHg according to manufacturer recommendations), and N-BFR (no BFR control).

Results

SC-BFR blunted post-exercise increases in carotid-femoral pulse wave velocity (p = 0.328) (+3.3%) whereas the other conditions showed elevations (MC-BFR +11.8% [p = 0.041], N-BFR +9.3% [p = 0.012]). Discomfort was lower in N-BFR compared to SC-BFR (p < 0.001) and MC-BFR (p = 0.035) but all displayed similar exertion (p = 0.176). Median total repetitions achieved were significantly less in SC-BFR (57 [25-75th percentile: 47-65) than MC-BFR (76 [63-91] (p = 0.043) and N-BFR [106 (97-148)] p = 0.005). Per set repetition volumes were similar on set 1 between SC-BFR (p < 0.001) and MC-BFR (p = 0.001) and were lower than N-BFR (p ≤ 0.001) whereas in sets 2-4, MC-BFR performed similar number of repetitions as N-BFR (p = 0.984-1.000).

Conclusion

Bladder design of a BFR cuff has an impact on the acute responses to exercise if applied according to recommended application guidelines, as SC-BFR impacts performance to a greater degree and mitigates post-exercise arterial stiffness responses compared to MC-BFR and N-BFR while both BFR conditions display greater levels of discomfort compared to N-BFR.

Clinical Trial Registration

NCT06276673.

Quantification and interpretation of nitric oxide-dependent cutaneous vasodilation during local heating

Human cutaneous microdialysis approaches for assessing nitric oxide (NO)-dependent blood flow include local heating (LH) of the skin until a plateau is reached, followed by infusion of a NO synthase inhibitor such as NG-nitro-l-arginine methyl ester (l-NAME); however, varied methods of quantifying and expressing NO-dependent vasodilation can obfuscate data interpretation and reproducibility. We retrospectively assessed NO-dependent vasodilation during LH to 39°C or 42°C, calculated as the 1) absolute contribution of the NO-dependent component (along with baseline and the non-NO-dependent component) to the total cutaneous vascular conductance (CVC) response to LH, normalized to maximal CVC (%CVCmax); 2) difference in %CVCmax (Δ%CVCmax) between the LH plateau and post-NO synthase inhibition (l-NAME plateau; Δ%CVCmax = LH plateau - l-NAME plateau); 3) percentage of the LH plateau attributable to Δ%CVCmax (%plateau = Δ%CVCmax/LH plateau × 100); and 4) %plateau when correcting for baseline. The LH plateaus during 39°C and 42°C were 48 ± 17%CVCmax (9 ± 5% baseline; 2 ± 4% non-NO dependent; 36 ± 15% NO dependent) and 88 ± 10%CVCmax (15 ± 8% baseline; 9 ± 10% non-NO dependent; 64 ± 13% NO dependent), respectively. The absolute contributions of the non-NO-dependent and NO-dependent components of the response (P < 0.0001) and the Δ%CVCmax (66 ± 14 vs. 38 ± 15%) were greater during 42°C compared with 39°C (all P ≤ 0.02); however, there were no differences between the two protocols in %plateau (75 ± 13 vs. 80 ± 10%; P = 0.57) or %plateauBL (88 ± 14 vs. 95 ± 8%; P = 0.31). For both protocols, the values were greater for %plateauBL versus Δ%CVCmax and %plateau (P ≤ 0.0001), and for %plateau versus Δ%CVCmax (P ≤ 0.05). Quantification of NO-dependent skin vasodilation responses to LH is dependent upon the mathematical approach and verbal description, which can meaningfully impact data interpretation and reproducibility.NEW & NOTEWORTHY Local heating protocols are commonly used in conjunction with intradermal microdialysis for assessing nitric oxide (NO)-dependent microvascular function in humans, but various methods used to quantify and describe NO-dependent vasodilation may impact data interpretation. We compared four approaches for quantifying NO-dependent cutaneous vasodilation during local heating at 39°C and 42°C. We identify discrepancies in calculated NO-dependent dilation responses that are dependent upon the mathematical approach and meaningfully impact data interpretation and reproducibility.

Menstrual cycle and the protective effects of remote ischemic preconditioning against endothelial ischemia/reperfusion injury: comparison with postmenopausal women

The aim of this study was to determine whether the capacity of remote ischemic preconditioning (IPC) against endothelial ischemia/reperfusion (I/R) injury changes across the menstrual cycle in premenopausal women and to compare IPC responses to postmenopausal women. Thirty-five women were studied (22 premenopausal/13 postmenopausal). Changes in endothelial function were determined during the early follicular vs. the late follicular phase (after positive urine ovulation test; Study 1), vs. the mid-luteal phase (after positive urine progesterone test; Study 2), and vs. estrogen-deficient postmenopausal women; Study 3). Endothelium-dependent vasodilation was assessed by the forearm blood flow (FBF) to reactive hyperemia with/without I/R injury with remote IPC (3 × 5 min cycles of upper arm ischemia). In the premenopausal women, peak FBF responses during the early follicular phase were blunted 20% (P < 0.0001) with I/R injury (from baseline: 23.4 ± 6.2 to 19.5 ± 4.9 mL/100 mL tissue/min) compared with the late follicular/mid-luteal phases despite IPC. In postmenopausal women, peak FBF was diminished (from: 21.1 ± 5.1 to 17.2 ± 4.4 mL/100 mL tissue/min), and total FBF (area under the curve) was decreased a third (-32%; P < 0.001) with I/R injury. Protection from I/R injury was preserved during the late follicular (from baseline: 21.7 ± 5.3 to 24.8 ± 5.9 mL/100 mL tissue/min; P = 0.109) and mid-luteal phases (from: 25.1 ± 3.9 to 27.2 ± 5.7 mL/100 mL tissue/min; P = 0.267). Reduced estrogen during the early follicular phase and the rise in estrogen associated with ovulation and the mid-luteal phase may contribute to changes in IPC-mediated protection in premenopausal women and shed light on how cardioprotection may change with ovarian hormone deficiency with the menopause transition.NEW & NOTEWORTHY The capacity of remote ischemic preconditioning to protect against vascular endothelial ischemia/reperfusion injury varies widely across the phases of the menstrual cycle in healthy premenopausal women. Robust protection was afforded during the late follicular and mid-luteal phases. In contrast, weakened protection was demonstrated during the early follicular phase, with a level of impairment similar to estrogen-deficient postmenopausal women.

The Effect of Acute Sleep Extension on Blood Pressure Is Dependent on the Change in Sleep Efficiency

The present study investigated the effect of acute sleep extension on blood pressure and microvascular vasodilation. Sleep and daily physical activity were objectively measured at home for two weeks using wrist actigraphy in 22 adults (60 ± 15 y). Vascular measurements were made in the morning on the 8th and 15th day. Participants spent at least 10 h in bed on the night prior to one of these testing days to extend sleep. Mean arterial blood pressure (MAP) and peak reactive hyperemia in the forearm were measured on each testing day. Reactive hyperemia and MAP were unaltered (p > 0.05) by sleep extension in the total sample. However, adults who experienced improved sleep efficiency with sleep extension (n = 10, 4.2 ± 1.4%) exhibited reduced MAP (-5.5 ± 4.6 mm Hg, p = 0.005) while adults who had little change or decreased sleep efficiency (n = 12, -1.7 ± 2.9%) showed no change in MAP. The reduction in MAP was significantly different between sleep efficiency groups (p = 0.005, Hedges' g = 1.21) after adjustment for sex and moderate-to-vigorous physical activity. The results of this study suggest that sleep extension has the potential to reduce blood pressure in midlife to older adults when the additional sleep time improves the quality of sleep.

Menstrual and oral contraceptive pill cycles minimally influence vascular function and associated cellular regulation in premenopausal females

Historical exclusion of females in research has been, in part, due to the perceived influence of natural menstrual (NAT) and oral contraceptive pill (OCP) cycles on vascular outcomes. NAT and OCP cycle phases may influence brachial artery (BA) endothelial function, however, findings are mixed. Minimal research has examined arterial stiffness, smooth muscle, and lower limb endothelial function. The purpose of this study was to investigate the influence of NAT and OCP cycles on cardiovascular outcomes and cellular regulation. Forty-nine premenopausal females (n = 17 NAT, n = 17 second generation OCP, n = 15 third generation OCP) participated in two randomized order visits in the low (LH, early follicular/placebo) and high (HH, midluteal/active) hormone cycle phases. BA and superficial femoral artery (SFA) endothelial function [flow-mediated dilation (FMD) test], smooth muscle function (nitroglycerine-mediated dilation test), and carotid and peripheral (pulse wave velocity) arterial stiffness were assessed. Cultured female human endothelial cells were exposed to participant serum for 24 h to examine endothelial nitric oxide synthase (eNOS) and estrogen receptor-α (ERα) protein content. BA FMD was elevated in the HH vs. LH phase, regardless of group (HH, 7.7 ± 3.5%; LH, 7.0 ± 3.3%; P = 0.02); however, allometric scaling for baseline diameter resulted in no phase effect (HH, 7.6 ± 2.6%; LH, 7.1 ± 2.6%; P = 0.052, d = 0.35). SFA FMD, BA, and SFA smooth muscle function, arterial stiffness, and eNOS and ERα protein content were unaffected. NAT and OCP phases examined have minimal influence on vascular outcomes and ERα-eNOS pathway, apart from a small effect on BA endothelial function partially explained by differences in baseline artery diameter. NEW & NOTEWORTHY Comprehensive evaluation of the cardiovascular system in naturally cycling and second and third generation OCP users indicates no major influence of hormonal phases examined on endothelial function and smooth muscle function in the arteries of the upper and lower limbs, arterial stiffness, or underlying cellular mechanisms. Study findings challenge the historical exclusion of female participants due to potentially confounding hormonal cycles; researchers are encouraged to consider the hormonal environment in future study design.

Comparison of analysis strategies to assess sex differences in microvascular reperfusion using near-infrared spectroscopy

The near-infrared spectroscopy (NIRS) vascular occlusion test (VOT) assesses microvascular reperfusion. Two strategies have been used to quantify reperfusion following reactive hyperemia, but it is unclear whether both yield similar results when comparing biological sex. This study aimed to determine whether sex differences in NIRS-based microvascular reperfusion are similarly apparent using the 10-s reactive hyperemia slope of the tissue saturation index (StO2) signal (slope 2) and the halftime to maximal reperfusion (T ½). Healthy, recreationally active males (n = 31) and females (n = 31) between 18 and 82 years took part in this study. A NIRS VOT was performed on the tibialis anterior muscle, and reperfusion was quantified using slope 2 (% s-1) and T ½ (s). Adipose tissue thickness (ATT) was higher in females (P = 0.009), which was associated with a lower StO2 (P = 0.001) and oxygenated hemoglobin (O2Hb) (P = 0.05) signal range. The StO2 slope 2 was significantly steeper in males versus females (P = 0.001) but not after correcting for ATT (P = 0.295). There were no sex differences in StO2 T ½ (P = 0.067) or O2Hb T ½ (P = 0.197). In a subset of males (n = 26) and females (n = 21) with similar ATT, there were no sex differences in StO2 slope 2 (P = 0.068), StO2 T ½ (P = 0.491), or O2Hb T ½ (P = 0.899). An ATT-corrected StO2 slope 2 or the T ½ approach is recommended for analysis of NIRS-based microvascular reperfusion when differences in ATT are present between sexes.NEW & NOTEWORTHY Sex differences in near-infrared spectroscopy (NIRS)-based microvascular reperfusion have been previously reported. We found that greater adipose tissue thickness in females reduces kinetic measures of NIRS-based microvascular reperfusion. Sex differences are eliminated when performing an adipose tissue thickness correction, when the NIRS signal range is accounted for, or when adipose tissue thickness is similar between sexes. This highlights the importance of considering factors that affect NIRS signals, such as adipose tissue thickness, when drawing comparisons between groups.

Differences in cardiovascular risk factors associated with sex and gender identity, but not gender expression, in young, healthy cisgender adults

Background

Sex differences exist in cardiovascular disease risk factors including elevated blood pressure and arterial stiffness, and decreased endothelial function in males compared to females. Feminine gender expression may be associated with elevated risk of acute coronary syndrome. However, no study has investigated the associations between sex, gender identity, and gender expression and cardiovascular disease risk factors in young adults.

Methods

One hundred and thirty participants (22 ± 3 years) underwent assessments of hemodynamics, arterial stiffness [pulse wave velocity (PWV)], and brachial artery endothelial function (flow-mediated dilation; %FMD). Participants completed a questionnaire capturing sex category (50 male/80 female), gender identity category (49 men/79 women/2 non-binary), and aspects of gender expression assessed by the Bem Sex Role Inventory-30 (39 androgynous/33 feminine/29 masculine/29 undifferentiated). Sex/gender identity category groups were compared using unpaired t-tests and gender expression groups compared using one-way ANOVAs.

Results

Resting systolic and mean arterial pressure (p < 0.01) were elevated in males vs. females. Central PWV was elevated in males [median (interquartile range): 6.4 (1.8) vs. 5.8 (2.2) m/s, p = 0.02]; however, leg and arm PWV were not different between sexes. %FMD was elevated in males vs. females, after accounting for a larger baseline artery diameter in males (8.8 ± 3.3% vs. 7.2 ± 3.1%, p = 0.02); since the majority of participants were cisgender, the same results were found examining gender identity (men vs. women). There were no differences across gender expression groups (p > 0.05).

Conclusions

Sex/gender identity category, but not gender expression, influence cardiovascular risk factors (blood pressure, arterial stiffness, endothelial function) in cisgender adults; further research is needed in gender-diverse populations.

Various modalities of resistance exercise promote similar acute cognitive improvements and hemodynamic increases in young, healthy adults

The aim was to examine the effects of modalities of acute resistance exercise (RE) on cognition and hemodynamics including internal carotid artery (ICA) blood flow (BF). Twenty adults completed familiarization and experimental visits. One-repetition maximum (1RM) for bilateral leg extension was quantified, and baseline executive functioning was determined from three run-in visits. Subsequent visits included three randomized, volume-equated, acute exercise bouts of 30 %1RM+blood flow restriction (BFR), 30 %1RM, and 70 %1RM. Both 30 %1RM trials completed four sets of exercise (1 × 30, 3 × 15), and the 70 %1RM condition completed four sets of 8 repetitions. BFR was induced with 40 % of the pressure to occlude the femoral arteries. 11 min following each exercise, participants completed the Stroop and Shifting Attention Tests. Baseline and post-exercise values were used to calculate change scores. The resulting mean change scores were evaluated with mixed factorial ANOVAs. A p≤0.05 was considered significant. All measured outcome variables increased in response to exercise. The ANOVAs for cognitive scores indicated no significant (p>0.05) interactions. For cognitive flexibility and executive function index, there were main effects of Sex. Change scores of the females were significantly greater than the males for cognitive flexibility (7.6 ± 5.9 vs. -2.6 ± 8.4 au; p=0.007) and executive function index (7.4 ± 4.6 vs. -2.5 ± 6.5 au; p=0.001). For ICA BF, there was no significant interaction or any main effect. The females exhibited a smaller exercise-induced increase in blood pressure compared to the males (17.7 ± 5.9 vs. 11.0 ± 4.1 mmHg; p=0.010). Each RE modality yielded acute improvements in cognition, but only for females. There were no cognitive improvements related to BFR such that each RE bout yielded similar results.

Effects of pre-exercise intake of plant- and animal-based foods on arterial function and aerobic exercise capacity in healthy young men: a randomized cross-over trial

The purpose of this study was to examine the effects of plant- versus animal-based food intake before exercise on arterial function and subsequent aerobic exercise capacity. Eleven healthy adult males (mean age, 22.6 ± 1.8 years) participated in this study. A plant- or animal-based randomized meal type crossover comparison was conducted on separate days with a uniform protein, fat, and carbohydrate balance. Both carotid-femoral pulse wave velocity (cfPWV), femoral-ankle pulse wave velocity (faPWV), and brachial artery flow-mediated dilatation (FMD) were measured as indexes of aortic and peripheral arterial stiffness and vascular endothelial function, respectively, before and at 120 min after the meal. After these measurements, maximal oxygen uptake was assessed using a graded power test on an electronically braked cycle ergometer. The results revealed that cfPWV was significantly lower, whereas FMD was significantly higher, at 120 min after compared with before the plant-based meal (p = 0.01 and 0.02, respectively). By contrast, cfPWV and FMD did not change at 120 min after compared with before the animal-based meal. In addition, faPWV did not change at 120 min after compared with before the meal for either meal type. Maximal oxygen uptake was higher in the plant- than in the animal-based meal type (p = 0.02). These results suggest that pre-exercise plant-based food intake may improve central arterial stiffness and vascular endothelial function, which may have favorable implications for aerobic exercise capacity.

Effects of Hormonal Contraception and the Menstrual Cycle on Fatigability and Recovery From an Anaerobic Exercise Test

ABSTRACT

Cabre, HE, Ladan, AN, Moore, SR, Joniak, KE, Blue, MNM, Pietrosimone, BG, Hackney, AC, and Smith-Ryan, AE. Effects of hormonal contraception and the menstrual cycle on fatigability and recovery from an anaerobic exercise test. J Strength Cond Res 38(7): 1256-1265, 2024-This study sought to evaluate the effects of oral contraceptive (OC) and hormonal intrauterine device (H-IUD) use, compared with a eumenorrheic (EUM) cycle, on fatigability and recovery between hormone the phases. Peak power (PP), average power (AP), fatigue index (FI), blood lactate, vessel diameter, and blood flow (BF) were measured from a repeated sprint cycle test (10 × 6 seconds) in 60, healthy, active women (mean ± SD ; age: 26.5 ± 7.0 years, BMI: 22.5 ± 3.7 kg·m -2 ) who used monophasic OC (≥6 months; n = 21), had a H-IUD (≥6 months; n = 20), or had regular naturally occurring menstrual cycle (≥3 months) or had a nonhormonal IUD (EUM; n = 19). Subjects were randomly assigned to begin in either the low-hormone phase (LHP) or high-hormone phase (HHP) and were tested once in each phase. Separate univariate analyses of covariances assessed the change from HHP to LHP between the groups, covaried for progesterone, with significance set at p ≤ 0.05. All groups demonstrated similar changes in PP, AP, FI, blood lactate, vessel diameter, and BF between the phases ( p > 0.05). Although not significant, AP was higher in LHP for OC (Δ -248.2 ± 1,301.4 W) and EUM (Δ -19.5 ± 977.7 W) and higher in HHP for H-IUD (Δ 369.3 ± 1,123.0 W). Oral contraceptive group exhibited a higher FI (Δ 2.0%) and reduced blood lactate clearance (Δ 2.5%) in HHP. In recreationally active women, hormonal contraception and hormone phases may minimally impact fatigue and recovery. Individual elite female athletes may benefit from understanding hormonal contraception type as performance and recovery may slightly vary across the cycle.

Effects of the Menstrual Cycle and Hormonal Contraceptive Use on Metabolic Outcomes, Strength Performance, and Recovery: A Narrative Review

The effects of female sex hormones on optimal performance have been increasingly recognized as an important consideration in exercise and sport science research. This narrative review explores the findings of studies evaluating the effects of menstrual cycle phase in eumenorrheic women and the use of hormonal contraception (oral contraceptives and hormonal intrauterine devices) on metabolism, muscular strength, and recovery in active females. Ovarian hormones are known to influence metabolism because estrogen is a master regulator of bioenergetics. Importantly, the menstrual cycle may impact protein synthesis, impacting skeletal muscle quality and strength. Studies investigating muscular strength in eumenorrheic women report equivocal findings between the follicular phase and luteal phase with no differences compared to oral contraceptive users. Studies examining recovery measures (using biomarkers, blood lactate, and blood flow) do not report clear or consistent effects of the impact of the menstrual cycle or hormonal contraception use on recovery. Overall, the current literature may be limited by the evaluation of only one menstrual cycle and the use of group means for statistical significance. Hence, to optimize training and performance in females, regardless of hormonal contraception use, there is a need for future research to quantify the intra-individual impact of the menstrual cycle phases and hormonal contraceptive use in active females.

The effect of self-identified arm dominance on exercising forearm hemodynamics and skeletal muscle desaturation

The human forearm model is commonly employed in physiological investigations exploring local vascular function and oxygen delivery; however, the effect of arm dominance on exercising forearm hemodynamics and skeletal muscle oxygen saturation (SmO2) in untrained individuals is poorly understood. Therefore, the purpose of this study was to explore the effect of self-identified arm dominance on forearm hemodynamics and SmO2 in untrained individuals during submaximal, non-ischemic forearm exercise. Twenty healthy individuals (23±4 years, 50% female; 80% right-handed) completed three-minute bouts of supine rhythmic (1 second contraction: 2 second relaxation duty cycle) forearm handgrip exercise at both absolute (10kg; 98N) and relative (30% of maximal voluntary contraction) intensities in each forearm. Beat-by-beat measures of forearm blood flow (FBF; ml/min), mean arterial blood pressure (MAP; mmHg) and flexor digitorum superficialis SmO2 (%) were obtained throughout and averaged during the final 30 seconds of rest, exercise, and recovery while forearm vascular conductance was calculated (FVC; ml/min/100mmHg). Data are Δ from rest (mean±SD). Absolute force production did not differ between non-dominant and dominant arms (97±11 vs. 98±13 N, p = 0.606) whereas relative force production in females did (69±24 vs. 82±25 N, p = 0.001). At both exercise intensities, FBFRELAX, FVCRELAX, MAPRELAX, and the time constant tau for FBF and SmO2 were unaffected by arm dominance (all p>0.05). While arm dominance did not influence SmO2 during absolute intensity exercise (p = 0.506), the non-dominant arm in females experienced an attenuated reduction in SmO2 during relative intensity exercise (-14±10 vs. -19±8%, p = 0.026)-though exercise intensity was also reduced (p = 0.001). The present investigation has demonstrated that arm dominance in untrained individuals does not impact forearm hemodynamics or SmO2 during handgrip exercise.

Sex-specific microvascular and hemodynamic responses to passive limb heating in young adults

OBJECTIVE

We examined sex-specific microvascular reactivity and hemodynamic responses under conditions of augmented resting blood flow induced by passive heating compared to normal blood flow.

METHODS

Thirty-eight adults (19 females) completed a vascular occlusion test (VOT) on two occasions preceded by rest with or without passive heating in a randomized, counterbalanced order. Skeletal muscle tissue oxygenation (StO2, %) was assessed with near-infrared spectroscopy (NIRS), and the rate of desaturation and resaturation as well as maximal StO2 (StO2max) and prolonged hypersaturation (area under the curve, StO2AUC) were quantified. Before the VOT, brachial artery blood flow (BABF), vascular conductance, and relative BABF (BABF normalized to forearm lean mass) were determined. Sex × condition ANOVAs were used. A p-value ≤.05 was considered statistically significant.

RESULTS

Twenty minutes of heating increased BABF compared to the control (102.9 ± 28.3 vs. 36.0 ± 20.9 mL min-1; p < .01). Males demonstrated greater BABF than females (91.9 ± 34.0 vs. 47.0 ± 19.1 mL min-1; p < .01). There was no sex difference in normalized BABF. There were no significant interactions for NIRS-VOT outcomes, but heat did increase the rate of desaturation (-0.140 ± 0.02 vs. -0.119 ± 0.03% s-1; p < .01), whereas regardless of condition, males exhibited greater rates of resaturation and StO2max than females.

CONCLUSIONS

These results suggest that blood flow is not the primary factor causing sex differences in NIRS-VOT outcomes.

Vascular adaptation to exercise: a systematic review and audit of female representation

Biological sex is a salient factor in exercise-induced vascular adaptation. Although a male bias is apparent in the literature, the methodological quality of available studies in females is not yet known. This systematic review with narrative synthesis aimed to assess available evidence of exercise interventions on endothelial function, measured using flow-mediated dilation, in otherwise healthy individuals and athletes. A standardized audit framework was applied to quantify the representation of female participants. Using a tiered grading system, studies that met best-practice recommendations for conducting physiological research in females were identified. A total of 210 studies in 5,997 participants were included, with 18% classified as athletes. The primary exercise mode and duration were aerobic (49%) and acute (61%), respectively. Despite 53% of studies (n = 111) including at least one female, female participants accounted for only 39% of the total study population but 49% of the athlete population. Majority (49%) of studies in females were conducted in premenopausal participants. No studies in naturally menstruating, hormonal contraceptive-users or in participants experiencing menstrual irregularities met all best-practice recommendations. Very few studies (∼5%) achieved best-practice methodological guidelines for studying females and those that did were limited to menopause and pregnant cohorts. In addition to the underrepresentation of female participants in exercise-induced vascular adaptation research, there remains insufficient high-quality evidence with acceptable methodological control of ovarian hormones. To improve the overall methodological quality of evidence, adequate detail regarding menstrual status should be prioritized when including females in vascular and exercise research contexts.

Influence of cardiorespiratory fitness and body composition on resting and post-exercise indices of vascular health in young adults

Poor cardiorespiratory fitness may mediate vascular impairments at rest and following an acute bout of exercise in young healthy individuals. This study aimed to compare flow mediated dilation (FMD) and vascular augmentation index (AIx75) between young adults with low, moderate, and high levels of cardiorespiratory fitness before and after an acute bout of aerobic exercise. Forty-three participants (22 men; 21 women) between 18 and 29 years of age completed the study. Participants were classified into low, moderate, and high health-related cardiorespiratory fitness groups according to age- and sex-based relative maximal oxygen consumption (V ˙ O2 max) percentile rankings. FMD was performed using Doppler ultrasound and AIx75 was performed using pulse wave analysis at baseline and 60-min after a 30-min bout of treadmill running at 70% V ˙ O2 max. A significant interaction (p ​= ​0.047; ηp2 ​= ​0.142) was observed, with the moderate fitness group exhibiting a higher FMD post-exercise compared with baseline ([6.7% ​± ​3.1%] vs. [8.5% ​± ​2.8%], p ​= ​0.028; d ​= ​0.598). We found a significant main effect of group for AIx75 (p ​= ​0.023; ηp2 ​= ​0.168), with the high fitness group exhibiting lower AIx75 compared to low fitness group ([-10% ​± ​10%] vs. [2% ​± ​10%], respectively, p ​= ​0.019; g ​= ​1.07). This was eliminated after covarying for body fat percentage (p ​= ​0.489). Our findings suggest that resting FMD and AIx75 responses are not significantly influenced by cardiorespiratory fitness, but FMD recovery responses to exercise may be enhanced in individuals with moderate cardiorespiratory fitness levels.

Using high-resolution imaging to study the impact of the Kalogon wheelchair cushion on blood flow in the gluteal area

AIM OF THE STUDY

This study investigated how the air-bladder offloading mode of the Orbiter by Kalogon wheelchair cushion (Orbiter) affected blood flow in the gluteal region of non-disabled subjects. The hypothesis was that the cushion's offloading mode would improve blood flow, resulting in reduced reactive hyperemia when compared to the static setting, or Loaded Control (LC). Furthermore, the study proposed a technique using a high-resolution image laser speckle contrast system to measure blood flow in the gluteal area.

METHODS

Two procedures were carried out, one with the participant sitting on a cushion in LC, and the second, the cushion was set to offloading mode. Blood flow was measured through data imaging after each procedure. Three trials were performed, starting and ending in different cushion bladders. Customized algorithms were used to select regions of interest on the images for calculations. The Wilcoxon Signed-Rank Test was conducted to compare the offloads and loaded control values of each region of interest. Results were considered significant at α = 0.05.

RESULTS

Ten healthy, non-disabled adults participated in the study, seven females and three males. There were no significant differences among the participants. However, results showed that seven subjects tended to decrease reactive hyperemia in the offload sequence of trial when the last two bladders offloaded were the sacrum followed by the right ischial tuberosity.

CONCLUSIONS

The high-resolution imager showed that the Orbiter Offloads helped reduce reactive hyperemia in seven subjects, potentially improving blood flow. More research is necessary to comprehend the mechanisms of these effects fully.

Menstrual cycle hormones and oral contraceptives: a multimethod systems physiology-based review of their impact on key aspects of female physiology

Hormonal changes around ovulation divide the menstrual cycle (MC) into the follicular and luteal phases. In addition, oral contraceptives (OCs) have active (higher hormone) and placebo phases. Although there are some MC-based effects on various physiological outcomes, we found these differences relatively subtle and difficult to attribute to specific hormones, as estrogen and progesterone fluctuate rather than operating in a complete on/off pattern as observed in cellular or preclinical models often used to substantiate human data. A broad review reveals that the differences between the follicular and luteal phases and between OC active and placebo phases are not associated with marked differences in exercise performance and appear unlikely to influence muscular hypertrophy in response to resistance exercise training. A systematic review and meta-analysis of substrate oxidation between MC phases revealed no difference between phases in the relative carbohydrate and fat oxidation at rest and during acute aerobic exercise. Vascular differences between MC phases are also relatively small or nonexistent. Although OCs can vary in composition and androgenicity, we acknowledge that much more work remains to be done in this area; however, based on what little evidence is currently available, we do not find compelling support for the notion that OC use significantly influences exercise performance, substrate oxidation, or hypertrophy. It is important to note that the study of females requires better methodological control in many areas. Previous studies lacking such rigor have contributed to premature or incorrect conclusions regarding the effects of the MC and systemic hormones on outcomes. While we acknowledge that the evidence in certain research areas is limited, the consensus view is that the impact of the MC and OC use on various aspects of physiology is small or nonexistent.

Considering hormones as sex- and gender-related factors in biomedical research: Challenging false dichotomies and embracing complexity

The inclusion of sex and gender considerations in biomedicine has been increasing in light of calls from research and funding agencies, governmental bodies, and advocacy groups to direct research attention to these issues. Although the inclusion of both female and male participants is often an important element, overreliance on a female-male binary tends to oversimplify the interactions between sex- and gender-related factors and health, and runs a risk of being influenced by cultural stereotypes about sex and gender. When biomedical researchers are examining how hormones associated with gender and sex may influence pathways of interest, it is of crucial importance to approach this work with a critical lens on the rhetoric used, and in ways that acknowledge the complexity of hormone physiology. Here, we document the ways in which discourses around sex, gender and hormones shape our scientific thinking and practice in biomedical research, and review how the existing scientific knowledge about hormones reflects a complex and dynamic reality that is often not reflected outside of specialist niches of hormone biology. Where biomedical scientists take up sex- and gender-associated hormones as a way of addressing sex and gender considerations, it is valuable for us to bring a critical lens to the rhetoric and discourses used, to employ a sex contextualist approach in designing experimentation, and be rigorous and reflexive about the approaches used in analysis and interpretation of data. These strategies will allow us to design experimentation that goes beyond binaries, and grapples more directly with the material intricacies of sex, gender, and hormones.

Effects of sex and menstrual cycle phase on celiac artery blood flow during dynamic moderate-intensity leg exercise in young individuals

The purpose of this study was to clarify the effect of sex and menstrual cycle phase on celiac artery blood flow during dynamic exercise in healthy young humans. Eleven healthy young females (21 ± 2 yr, means ± SD) and 10 males (23 ± 3 yr) performed dynamic knee-extension and -flexion exercises at 30% of heart rate reserve for 4 min. The percent changes from baseline (Δ) for mean arterial blood pressure (MAP), mean blood flow (celMBF) in the celiac artery, and celiac vascular conductance (celVC) during exercise were calculated. Arterial blood pressure was measured using an automated sphygmomanometer, and celiac artery blood flow was recorded by Doppler ultrasonography. Female subjects performed the exercise test in the early follicular phase (EF) and in the midluteal phase (ML) of their menstrual cycle. The increase in MAP during exercise was not significantly (P > 0.05) different between sexes or between menstrual cycle phases (ΔMAP, EF in females: +16.6 ± 6.4%, ML in females: +20.2 ± 11.7%, and males: +19.9 ± 12.2%). The celMBF decreased during exercise in each group, but the response was not significantly (P > 0.05) different between sexes or between menstrual cycle phases (ΔcelMBF, EF in females: -24.6 ± 15.5%, ML in females: -25.2 ± 18.7%, and males: -29.2 ± 4.0%). The celVC decreased during dynamic exercise in each group, with no significant (P > 0.05) difference in the responses between sexes or between menstrual cycle phases (ΔcelVC, EF in females: -38.3 ± 15.0%, ML in females: -41.5 ± 19.1%, and males: -43.4 ± 7.2%). These results suggest that sex and menstrual cycle phase have minimal influence on hemodynamic responses in the splanchnic artery during dynamic moderate-intensity exercise in young healthy individuals.NEW & NOTEWORTHY During dynamic exercise, splanchnic organ blood flow is reduced from resting values. Whether sex and menstrual cycle phase influence splanchnic blood flow responses during exercise remains unknown. We show that the decrease in celiac artery blood flow during dynamic leg exercise does not differ between young females and males or between menstrual cycle phases. In young individuals, sex and menstrual cycle have minimal influence on splanchnic artery hemodynamic responses during dynamic moderate-intensity leg exercise.

Vascular Responses to Passive and Active Movement in Premenopausal Females: Comparisons across Sex and Menstrual Cycle Phase

PURPOSE

Adequate, robust vascular responses to passive and active movement represent two distinct components linked to normal, healthy cardiovascular function. Currently, limited research exists determining if these vascular responses are altered in premenopausal females (PMF) when compared across sex or menstrual cycle phase.

METHODS

Vascular responses to passive leg movement (PLM) and handgrip (HG) exercise were assessed in PMF ( n = 21) and age-matched men ( n = 21). A subset of PMF subjects ( n = 11) completed both assessments during the early and late follicular phase of their menstrual cycle. Microvascular function was assessed during PLM via changes in leg blood flow, and during HG exercise, via steady-state arm vascular conductance. Macrovascular (brachial artery [BA]) function was assessed during HG exercise via BA dilation responses as well as BA shear rate-dilation slopes.

RESULTS

Leg microvascular function, determined by PLM, was not different between sexes or across menstrual cycle phase. However, arm microvascular function, demonstrated by arm vascular conductance, was lower in PMF compared with men at rest and during HG exercise. Macrovascular function was not different between sexes or across menstrual cycle phase.

CONCLUSIONS

This study identified similar vascular function across sex and menstrual cycle phase seen in microvasculature of the leg and macrovascular (BA) of the arm. Although arm microvascular function was unaltered by menstrual cycle phase in PMF, it was revealed to be significantly lower when compared with age-matched men highlighting a sex difference in vascular/blood flow regulation during small muscle mass exercise.

Racial Differences in Blood Pressure and Autonomic Recovery Following Acute Supramaximal Exercise in Women

Despite the growing popularity of high-intensity anaerobic exercise, little is known about the acute effects of this form of exercise on cardiovascular hemodynamics or autonomic modulation, which might provide insight into the individual assessment of responses to training load. The purpose of this study was to compare blood pressure and autonomic recovery following repeated bouts of acute supramaximal exercise in Black and White women. A convenience sample of twelve White and eight Black young, healthy women were recruited for this study and completed two consecutive bouts of supramaximal exercise on the cycle ergometer with 30 min of recovery in between. Brachial and central aortic blood pressures were assessed by tonometry (SphygmoCor Xcel) at rest and 15-min and 30-min following each exercise bout. Central aortic blood pressure was estimated using brachial pressure waveforms and customized software. Autonomic modulation was measured in a subset of ten participants by heart-rate variability and baroreflex sensitivity. Brachial mean arterial pressure and diastolic blood pressure were significantly higher in Blacks compared to Whites across time (race effect, p = 0.043 and p = 0.049, respectively). Very-low-frequency and low-frequency bands of heart rate variability, which are associated with sympathovagal balance and vasomotor tone, were 22.5% and 24.9% lower, respectively, in Blacks compared to Whites (race effect, p = 0.045 and p = 0.006, respectively). In conclusion, the preliminary findings of racial differences in blood pressure and autonomic recovery following supramaximal exercise warrant further investigations of tailored exercise prescriptions for Blacks and Whites.

Contrast-enhanced ultrasound repeatability for the measurement of skeletal muscle microvascular blood flow

NEW FINDINGS

What is the central question of this study? Contrast-enhanced ultrasound (CEUS) can be used to directly assess skeletal muscle perfusion but its day-to-day repeatability over time has not yet been validated: is CEUS a repeatable method for the measurement of skeletal muscle microvascular blood flow (MBF) at rest and in response to exercise, across independent assessment sessions? What is the main finding and its importance? A strong agreement between CEUS MBF measures across sessions suggests it is a repeatable method for assessing skeletal muscle perfusion over time. This validation provides confidence for incorporating these measures into longitudinal studies such as a chronic intervention or disease progression to gain further knowledge of skeletal muscle microvascular function.

ABSTRACT

Contrast-enhanced ultrasound (CEUS) can be used to directly assess skeletal muscle perfusion. However, its repeatability over time has not yet been validated and therefore its use in longitudinal measures (i.e., exploring the impact of a chronic intervention or disease progression) is limited. This study aimed to determine the repeatability of CEUS for the measurement of skeletal muscle microvascular blood flow (MBF) at baseline and in response to exercise, across independent assessment sessions. Ten healthy volunteers (five female; 30 ± 6 years) had CEUS of the right vastus lateralis recorded in two separate sessions, 14 days apart. Measurements were taken at baseline, during an isometric leg extension and during recovery. Acoustic intensity data from a region of interest were plotted as a replenishment curve to obtain blood volume (A) and flow velocity (β) values from a one-phase association non-linear regression of mean tissue echogenicity. Linear regression and Bland-Altman analyses of A and β values were performed, with significance assumed as P < 0.05. Strong positive correlations were observed across sessions for all A and β values (both P < 0.0001). Bland-Altman analysis showed a bias (SD) of -0.013 ± 1.24 for A and -0.014 ± 0.31 for β. A bias of 0.201 ± 0.770 at baseline, 0.527 ± 1.29 during contraction and -0.203 ± 1.29 at recovery was observed for A, and -0.0328 ± 0.0853 (baseline), -0.0446 ± 0.206 (contraction) and 0.0382 ± 0.233 (recovery) for β. A strong agreement between CEUS MBF measures across independent sessions suggests it to be a repeatable method for assessing skeletal muscle perfusion over time, and therefore facilitates wider use in longitudinal studies.

Training-induced impairment of endothelial function in track and field female athletes

Professional athletes are often exposed to high training loads that may lead to overfatigue, overreaching and overtraining that might have a detrimental effects on vascular health. We determined the effects of high training stress on endothelial function assessed by the flow-mediated dilation (FMD) and markers of glycocalyx shedding. Vascular examination as well as broad biochemical, hormonal and cardiometabolic evaluation of sprint and middle-distance female runners were performed after 2 months of preparatory training period and compared to age-matched control group of women. Female athletes presented with significantly reduced FMD (p < 0.01) and higher basal serum concentrations of hyaluronan (HA) and syndecan-1 (SDC-1) (p < 0.05 and p < 0.001, respectively), that was accompanied by significantly lower basal serum testosterone (T) and free testosterone (fT) concentrations (p < 0.05) and higher cortisol (C) concentration (p < 0.05). It resulted in significantly lower T/C and fT/C ratios in athletes when compared to controls (p < 0.01). Moreover, fT/C ratio were significantly positively correlated to FMD and negatively to HA concentrations in all studied women. Accordingly, the training load was significantly negatively correlated with T/C, fT/C and FMD and positively with the concentrations of HA and SDC-1. We concluded that young female track and field athletes subjected to physical training developed impairment of endothelial function that was associated with anabolic-catabolic hormone balance disturbances. Given that training-induced impairment of endothelial function may have a detrimental effects on vascular health, endothelial status should be regularly monitored in the time-course of training process to minimalize vascular health-risk in athletes.

Aortic stiffness increases during prolonged sitting independent of intermittent standing or prior exercise

INTRODUCTION

Adverse vascular responses can occur during prolonged sitting, including stiffening of the aortic artery which may contribute to cardiovascular disease. Few studies have investigated the impact of intermittent standing and/or prior exercise as strategies to attenuate these potentially deleterious vascular changes.

PURPOSE

To investigate central vascular health responses during prolonged sitting, with and without intermittent standing and/or prior exercise.

METHODS

Fifteen males aged 18 to 31 years were recruited. Subjects completed a control condition [Sitting Only (SO)], and three randomized strategy conditions [Sitting Plus Standing (SSt), Exercise Plus Sitting (ES), Exercise Plus Sitting Plus Standing (ESSt)]. For all conditions, measurements of carotid-femoral pulse wave velocity (cfPWV) were taken at pre- and post-intervention, and brachial and central blood pressure (BP) at pre-, 1-h, 2-h, and 3-h intervention.

RESULTS

cfPWV significantly increased from pre- to post-intervention for all conditions (all p ≤ 0.043), as did brachial mean arterial pressure (MAP) and diastolic BP, and central MAP and diastolic BP for the control condition (all p ≤ 0.022). Brachial and central systolic BP were significantly higher during SO compared to ESSt at 1 h, and compared to ES for central systolic BP (all p ≤ 0.036).

CONCLUSIONS

Strategies of intermittent standing and/or prior exercise may not prevent aortic stiffening during sitting but may attenuate BP elevations in the brachial and aortic arteries. Future research should investigate causal mechanistic links between sitting and aortic stiffening, and other attenuation strategies.

Correlations between salivary- and blood-derived gonadal hormone assessments and implications for inclusion of female participants in research studies

Even in the 21st century, female participants continue to be underrepresented in human physiology research. This underrepresentation is attributable in part to the perception that the inclusion of females is more time consuming, less convenient, and more expensive relative to males because of the need to account for the menstrual cycle in cardiovascular study designs. Accounting for menstrual cycle-induced fluctuations in gonadal hormones is important, given established roles in governing vascular function and evidence that failure to consider gonadal hormone fluctuations can result in misinterpretations of biomarkers of cardiovascular disease. Thus, for cardiovascular researchers, the inclusion of females in research studies implies a necessity to predict, quantify, and/or track indexes of menstrual cycle-induced changes in hormones. It is here that methodologies are lacking. Gold standard measurement requires venous blood samples, but this technique is invasive and can become both expensive and technically preclusive when serial measurements are required. To this end, saliva-derived measures of gonadal hormones provide a means of simple, noninvasive hormone tracking. To investigate the feasibility of this technique as a means of facilitating research designs that take the menstrual cycle into account, the purpose of this review was to examine literature comparing salivary and blood concentrations of the primary gonadal hormones that fluctuate across the menstrual cycle: estradiol and progesterone. The data indicate that there appear to be valid and promising applications of salivary gonadal hormone monitoring, which may aid in the inclusion of female participants in cardiovascular research studies.

Sex differences in musculoskeletal injury and disease risks across the lifespan: Are there unique subsets of females at higher risk than males for these conditions at distinct stages of the life cycle?

Sex differences have been reported for diseases of the musculoskeletal system (MSK) as well as the risk for injuries to tissues of the MSK system. For females, some of these occur prior to the onset of puberty, following the onset of puberty, and following the onset of menopause. Therefore, they can occur across the lifespan. While some conditions are related to immune dysfunction, others are associated with specific tissues of the MSK more directly. Based on this life spectrum of sex differences in both risk for injury and onset of diseases, a role for sex hormones in the initiation and progression of this risk is somewhat variable. Sex hormone receptor expression and functioning can also vary with life events such as the menstrual cycle in females, with different tissues being affected. Furthermore, some sex hormone receptors can affect gene expression independent of sex hormones and some transitional events such as puberty are accompanied by epigenetic alterations that can further lead to sex differences in MSK gene regulation. Some of the sex differences in injury risk and the post-menopausal disease risk may be "imprinted" in the genomes of females and males during development and sex hormones and their consequences only modulators of such risks later in life as the sex hormone milieu changes. The purpose of this review is to discuss some of the relevant conditions associated with sex differences in risks for loss of MSK tissue integrity across the lifespan, and further discuss several of the implications of their variable relationship with sex hormones, their receptors and life events.

In vivo arterial stiffness, but not isolated artery endothelial function, varies with the mouse estrous cycle

With the increasing appreciation for sex as a biological variable and the inclusion of female mice in research, it is important to understand the influence of the estrous cycle on physiological function. Sex hormones are known to modulate vascular function, but the effects of the mouse estrous cycle phase on arterial stiffness, endothelial function, and arterial estrogen receptor expression remain unknown. In 23 female C57BL/6 mice (6 mo of age), we determined the estrous cycle stage via vaginal cytology and plasma hormone concentrations. Aortic stiffness, assessed by pulse wave velocity, was lower during the estrus phase compared with diestrus. In ex vivo assessment of isolated pressurized mesenteric and posterior cerebral arteries, the responses to acetylcholine, insulin, and sodium nitroprusside, as well as nitric oxide-mediated dilation, were not different between estrous cycle phases. In the aorta, expression of phosphorylated estrogen receptor-α was higher for mice in estrus compared with mice in proestrus. In the cerebral arteries, gene expression for estrogen receptor-β (Esr2) was lowest for mice in estrus compared with diestrus and proestrus. These results demonstrate that the estrus phase is associated with lower in vivo large artery stiffness in mice. In contrast, ex vivo resistance artery endothelial function is not different between estrous cycle phases. Estrogen receptor expression is modulated by the estrus cycle in an artery-dependent manner. These results suggest that the estrous cycle phase should be considered when measuring in vivo arterial stiffness in young female mice.NEW & NOTEWORTHY To design rigorous vascular research studies using young female rodents, the influence of the estrous cycle on vascular function must be known. We found that in vivo aortic stiffness was lower during estrus compared with the diestrus phase in female mice. In contrast, ex vivo mesenteric and cerebral artery endothelial function did not differ between estrous cycle stages. These results suggest that the estrous cycle stage should be accounted for when measuring in vivo arterial stiffness.

Brachial artery responses to acute hypercapnia: The roles of shear stress and adrenergic tone

NEW FINDINGS

What is the central question of this study? What are the contributions of shear stress and adrenergic tone to brachial artery vasodilatation during hypercapnia? What is the main finding and its importance? In healthy young adults, shear-mediated vasodilatation does not occur in the brachial artery during hypercapnia, as elevated α₁-adrenergic activity typically maintains vascular tone and offsets distal vasodilatation controlling flow.

ABSTRACT

We aimed to assess the shear stress dependency of brachial artery (BA) responses to hypercapnia, and the α₁-adrenergic restraint of these responses. We hypothesized that elevated shear stress during hypercapnia would cause BA vasodilatation, but where shear stress was prohibited (via arterial compression), the BA would not vasodilate (study 1); and, in the absence of α₁-adrenergic activity, blood flow, shear stress and BA vasodilatation would increase (study 2). In study 1, 14 healthy adults (7/7 male/female, 27 ± 4 years) underwent bilateral BA duplex ultrasound during hypercapnia (partial pressure of end-tidal carbon dioxide, +10.2 ± 0.3 mmHg above baseline, 12 min) via dynamic end-tidal forcing, and shear stress was reduced in one BA using manual compression (compression vs. control arm). Neither diameter nor blood flow was different between baseline and the last minute of hypercapnia (P = 0.423, P = 0.363, respectively) in either arm. The change values from baseline to the last minute, in diameter (%; P = 0.201), flow (ml/min; P = 0.234) and conductance (ml/min/mmHg; P = 0.503) were not different between arms. In study 2, 12 healthy adults (9/3 male/female, 26 ± 4 years) underwent the same design with and without α₁-adrenergic receptor blockade (prazosin; 0.05 mg/kg) in a placebo-controlled, double-blind and randomized design. BA flow, conductance and shear rate increased during hypercapnia in the prazosin control arm (interaction, P < 0.001), but in neither arm during placebo. Even in the absence of α₁-adrenergic restraint, downstream vasodilatation in the microvasculature during hypercapnia is insufficient to cause shear-mediated vasodilatation in the BA.

Tracking peripheral vascular function for six months in young adults following SARS-CoV-2 infection

SARS-CoV-2 infection is known to instigate a range of physiologic perturbations, including vascular dysfunction. However, little work has concluded how long these effects may last, especially among young adults with mild symptoms. To determine potential recovery from acute vascular dysfunction in young adults (8 M/8F, 21 ± 1 yr, 23.5 ± 3.1 kg⋅m-2 ), we longitudinally tracked brachial artery flow-mediated dilation (FMD) and reactive hyperemia (RH) in the arm and hyperemic response to passive limb movement (PLM) in the leg, with Doppler ultrasound, as well as circulating biomarkers of inflammation (interleukin-6, C-reactive protein), oxidative stress (thiobarbituric acid reactive substances, protein carbonyl), antioxidant capacity (superoxide dismutase), and nitric oxide bioavailability (nitrite) monthly for a 6-month period post-SARS-CoV-2 infection. FMD, as a marker of macrovascular function, improved from month 1 (3.06 ± 1.39%) to month 6 (6.60 ± 2.07%; p < 0.001). FMD/Shear improved from month one (0.10 ± 0.06 AU) to month six (0.18 ± 0.70 AU; p = 0.002). RH in the arm and PLM in the leg, as markers of microvascular function, did not change during the 6 months (p > 0.05). Circulating markers of inflammation, oxidative stress, antioxidant capacity, and nitric oxide bioavailability did not change during the 6 months (p > 0.05). Together, these results suggest some improvements in macrovascular, but not microvascular function, over 6 months following SARS-CoV-2 infection. The data also suggest persistent ramifications for cardiovascular health among those recovering from mild illness and among young, otherwise healthy adults with SARS-CoV-2.

Cardiovascular Function in Different Phases of the Menstrual Cycle in Healthy Women of Reproductive Age

Background: Sex hormones influence the cardiovascular (CV) function in women. However, it is uncertain whether their physiological variation related to the regular menstrual cycle affects the CV system. We studied changes in the hemodynamic profile and body’s water content and their relation to sex hormone concentration in healthy women during the menstrual cycle. Material and methods: Forty-five adult women were examined during the early follicular, late follicular, and mid-luteal phases of the same menstrual cycle. The hemodynamic profile was estimated non-invasively by cardiac impedance while water content was estimated by total body impedance. Results were compared with repeated measures ANOVA with post-test, if applicable. Results: There were no significant changes in most hemodynamic and water content parameters between the menstrual cycle phases in healthy women. Left ventricular ejection time differed significantly among phases of the menstrual cycle, with shorter values in the mid-luteal phase (308.4 vs. 313.52 ms, p < 0.05) compared to the late follicular phase. However, the clinical relevance of such small differences is negligible. Conclusions: Changes in sex hormones during the physiological menstrual cycle appear to have no considerable effect on healthy women’s hemodynamic function and water accumulation.

Effects of orally administered hormonal contraceptives on the musculoskeletal system of healthy premenopausal women-A systematic review

Introduction

The musculoskeletal system (MSK) is one of the extragonadal target tissues of sex hormones: osteoblasts and osteocytes express estrogen receptors, while in fibroblasts of the anterior cruciate ligament (ACL) and myocytes of the vastus lateralis muscle (MVL), estrogen and progesterone receptors can be detected by immunoassay. Indeed, upon binding of sex hormones to the extragonadal receptors, the MSK seems to respond to varying levels of sex hormones with structural adaptation. Hormonal contraceptives can affect the musculoskeletal system; however, there is a lack of high-quality studies, and no recommendation for female athletes exists.

Material and Methods

This is a systematic review of publications on the effects of oral hormonal contraceptives on the biomechanical properties of tendons, muscles and ligaments, muscle strength, and soft tissue regeneration. A systematic database search was performed using MESH keywords and PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) methodology in Pubmed and Cochrane to identify studies investigating the influence of oral hormonal contraceptives on muscles, tendons, and ligaments of healthy, adult, premenopausal women. The risk of bias in the studies included was assessed by two independent researchers using the ROBINS-I Tool.

Results

Nine comparative studies were identified that met the inclusion criteria. Endpoints were muscle strength and biomechanical tissue properties. No significant influence of oral hormonal contraceptives on muscle strength was found, although general muscle growth and Type I fiber growth were found to be significantly increased in a dose-dependent manner. There was a negative effect on regeneration of muscle strength after exercise. The stiffness of tendons remained unchanged, while their size adaptation to load increased.

Conclusion

The anabolic effect could be beneficial for specific sports, whereas reduced muscle regeneration could be disadvantageous for women exercising with high-performance demands. The different effects on tendons and ligaments and the functional consequences of altered ligament and muscle stiffness, especially with regard to synthetic hormones, should be further investigated.

High-intensity functional exercise does not cause persistent elevations in augmentation index in young men and women

Elevations in central augmentation index (AIx) are predictive of cardiovascular disease. Our objective was to examine AIx immediately and 24-hrs following an acute bout of high-intensity functional training (HIFT) in apparently healthy young adults. A second aim compared the exercise induced AIx recovery response between men and women. Thirty-two recreationally active younger adults (n=16 men) were tested. Baseline central hemodynamic measures were assessed, followed by a single bout of bodyweight HIFT. The HIFT included four rounds of burpees, jump squats, split squats, and walking lunges. Assessments were repeated 5-, 10-, 15- and 24-hrs post exercise. AIx was normalized to a heart rate of 75 bpm (AIx75). There was a significant main effect of time on AIx75 across all groups (p<0.001) with AIx75 increasing at all acute timepoints compared with baseline and returning to resting values 24-hrs post-exercise. When examining sex differences after covarying for height and body fat percentage, we found no time*sex interaction (p=0.62), or main effect for sex (p=0.41), but the significant main effect of time remained (p<0.001). The AIx75 response to HIFT follows a similar recovery pattern as previously studied modes of exercise with no residual effects 24 hrs later and no differences between men and women indicating no persistent cardiovascular strain in younger adults participating in this mode of exercise.

Impact of prolonged sitting interruption strategies on shear rate, flow-mediated dilation and blood flow in adults: A systematic review and meta-analysis of randomized cross-over trials

Prolonged sitting has been shown to affect endothelial function. Strategies that promote interruption of sitting have shown varying results on the shear rate (SR), flow-mediated dilation (FMD) and blood flow (BF). Thus, we conducted a systematic review and meta-analysis to 1) increase the existing knowledge of the impact of sitting interruption in the prevention of endothelial dysfunction in adults and 2) determine the effect of the sitting interruption strategies on SR, FMD, BF. Literature search was carried out through 7 databases. A random effects model was used to provide the overall mean difference with a 95%CI, and forest plots were generated for pooled estimates of each study outcome. Assessment of biases was performed using ROB2 and considerations for crossover trials. Prolonged sitting interruption strategies showed a significant effect in increasing SR (MD: 7.58 s^-1; 95% CI: 3.00 to 12.17), FMD (MD: 1.74%; 95% CI: 0.55 to 2.93) and BF (MD: 12.08 ml/min; 95% CI: 7.61 to 16.55) when compared with the uninterrupted prolonged sitting condition. Prolonged sitting interruption strategies significantly increase SR, FMD and BF, therefore, they represent a considerable effective preventive method on endothelial dysfunction caused by acute exposure to uninterrupted prolonged sitting.

Blood flow restriction and stimulated muscle contractions do not improve metabolic or vascular outcomes following glucose ingestion in young, active individuals

Glucose ingestion and absorption into the blood stream can challenge glycemic regulation and vascular endothelial function. Muscular contractions in exercise promote a return to homeostasis by increasing glucose uptake and blood flow. Similarly, muscle hypoxia supports glycemic regulation by increasing glucose oxidation. Blood flow restriction (BFR) induces muscle hypoxia during occlusion and reactive hyperemia upon release. Thus, in the absence of exercise, electric muscle stimulation (EMS) and BFR may offer circulatory and glucoregulatory improvements. In 13 healthy, active participants (27±3yr, 7 female) we tracked post-glucose (oral 100g) glycemic, cardiometabolic and vascular function measures over 120min following four interventions: 1) BFR, 2) EMS, 3) BFR+EMS or 4) Control. BFR was applied at 2min intervals for 30min (70% occlusion), EMS was continuous for 30min (maximum-tolerable intensity). Glycemic and insulinemic responses did not differ between interventions (partial η2=0.11-0.15, P=0.2); however, only BFR+EMS demonstrated cyclic effects on oxygen consumption, carbohydrate oxidation, muscle oxygenation, heart rate, and blood pressure (all P<0.01). Endothelial function was reduced 60min post-glucose ingestion across interventions and recovered by 120min (5.9±2.6% vs 8.4±2.7%; P<0.001). Estimated microvascular function was not meaningfully different. Leg blood flow increased during EMS and BFR+EMS (+656±519mL•min-1, +433±510mL•min-1; P<0.001); however, only remained elevated following BFR intervention 90min post-glucose (+94±94mL•min-1; P=0.02). Superimposition of EMS onto cyclic BFR did not preferentially improve post-glucose metabolic or vascular function amongst young, active participants. Cyclic BFR increased blood flow delivery 60min beyond intervention, and BFR+EMS selectively increased carbohydrate usage and reduced muscle oxygenation warranting future clinical assessments.

Comparison of the acute effects of ankle bathing versus moderate-intensity aerobic exercise on vascular function in young adults

We examined the efficacy of ankle bathing versus aerobic exercise to improve vascular function in young adults who were randomized to aerobic exercise (AE) (n = 13, 40%-60% of heart rate reserve), ankle bathing (AB) (n = 15, 43 °C), or a control condition (CON) (n = 14, ankle bathing, 36 °C) for 40 min. Conduit vessel function [brachial artery flow-mediated dilation (FMD)], carotid and femoral artery blood flow and shear rate (SR), and arterial stiffness [carotid-to-femoral pulse wave velocity (cf-PWV), augmentation index (AIx@75), β-stiffness index, and arterial compliance] were evaluated. Compared with CON, AE and AB increased FMD at 30 min and 90 min (interaction: p < 0.05); AB decreased carotid artery blood flow and SR at 30 min, while both AE and AB increased femoral artery blood flow and SR at 30 min and 90 min (interaction: p < 0.05); AE and AB decreased cf-PWV and AIx@75 at 30 min and 90 min (interaction: p < 0.05); and AE improved both carotid and femoral β-stiffness index and arterial compliance, while AB reduced β-stiffness index and increased arterial compliance only in the femoral artery (interaction: p < 0.05). These findings suggest that ankle bathing may serve as an alternative strategy for enhancing vascular function. Novelty: We observed similar improvements in conduit vessel function, femoral artery blood flow and shear rate, and arterial stiffness following ankle bathing and acute aerobic exercise in young adults. These findings have identified ankle bathing as a potential therapeutic strategy for enhancing vascular function, which may be particularly relevant for those with limited ability to engage in regular aerobic exercise.

The Role of Follicle-stimulating Hormone in Vascular Dysfunction Observed in Hematopoietic Cell Transplant Recipients

Childhood cancer survivors who receive a hematopoietic cell transplantation (HCT) are at increased risk for follicle-stimulating hormone (FSH) abnormalities, which may have a substantial negative impact on vascular function. The purpose of this study was to examine the association of vascular function with FSH in HCT recipients, non-HCT recipients and healthy controls. The study included childhood cancer survivors who were HCT recipients (n=24) and non-HCT recipients (n=308), and a control group of healthy siblings (n=211) all between 9 and 18 years old. Vascular measures of carotid artery structure and function (compliance and distensibility), brachial artery flow-mediated dilation and endothelial-independent dilation were measured using ultrasound imaging. A fasting blood sample was collected to measure hormone levels. FSH was significantly higher in HCT recipients compared with non-HCT recipients and healthy controls (P<0.01). Carotid compliance and distensibility were significantly lower in HCT and non-HCT recipients compared with healthy controls (P<0.05). Higher FSH was associated with decreased carotid compliance (P<0.05). This study's results suggest that higher levels of FSH in HCT recipients may result in significant reductions in vascular function compared with non-HCT recipients and healthy controls. Therefore, gonadotropin endocrine dysfunction, particularly abnormal FSH levels, may be an underlying mechanism of vascular dysfunction.

Examination of Sex-Specific Participant Inclusion in Exercise Physiology Endothelial Function Research: A Systematic Review

Background

To combat historical underrepresentation of female participants in research, guidelines have been established to motivate equal participation by both sexes. However, the pervasiveness of female exclusion has not been examined in vascular exercise physiology research. The purpose of this study was to systematically quantify the sex-specific prevalence of human participants and identify the rationales for sex-specific inclusion/exclusion in research examining the impact of exercise on vascular endothelial function.

Methods

A systematic search was conducted examining exercise/physical activity and vascular endothelial function, assessed via flow mediated dilation. Studies were categorized by sex: male-only, female-only, or mixed sex, including examination of the sample size of males and females. Analysis was performed examining sex-inclusion criteria in study design and reporting and rationale for inclusion/exclusion of participants on the basis of sex. Changes in proportion of female participants included in studies were examined over time in 5 year cohorts.

Results

A total of 514 studies were identified, spanning 26 years (1996–2021). Of the total participants, 64% were male and 36% were female, and a male bias was identified (32% male-only vs. 12% female-only studies). Proportions of female participants in studies remained relatively constant in the last 20 years. Male-only studies were less likely to report sex in the title compared to female-only studies (27 vs. 78%, p < 0.001), report sex in the abstract (72 vs. 98%, p < 0.001) and justify exclusion on the basis of sex (15 vs. 55%, p < 0.001). Further, male-only studies were more likely to be conducted in healthy populations compared to female-only studies (p = 0.002). Qualitative analysis of justifications identified four themes: sex-specific rationale or gap in the literature, exclusion of females based on the hormonal cycle or sex-differences, maintaining congruence with the male norm, and challenges with recruitment, retention and resources.

Conclusions

This systematic review provides the first analysis of sex-based inclusion/exclusion and rationale for sex-based decisions in human vascular exercise physiology research. These findings contribute to identifying the impact of research guidelines regarding inclusion of males and females and the perceived barriers to designing studies with equal sex participation, in an effort to increase female representation in vascular exercise physiology research.

Systematic Review Registration:

CRD42022300388.

Effect of five nights of sleep extension on peripheral vascular function: a randomized crossover investigation into long sleep duration

Long sleep duration, defined as ≥9 h, is associated with increased cardiovascular mortality. We sought to determine the effect of sleep extension on peripheral vascular health. Twelve middle-aged adults were randomly assigned to spend five nights with 8 h (control) or 10+ hours time in bed (TIB) in a crossover fashion. Sleep was assessed using wrist actigraphy. Peak reactive hyperemia in the forearm was measured using venous-occlusion plethysmography as an index of microvascular vasodilation. Nighttime and morning blood pressure was recorded along with pulse wave velocity (arterial stiffness). Average sleep duration was 7.1 ± 0.3 and 9.3 ± 0.3 h for 8 and 10+ hours TIB (P < 0.001), respectfully. On average, sleep was extended by 127 ± 29 min with nine participants reaching average sleep durations >9 h. Extended sleep did not change nighttime or morning blood pressure, or pulse wave velocity (all P > 0.05). In contrast, peak forearm vascular conductance (FVC, 0.27 ± 0.08 vs. 0.23 ± 0.07 ml/100 ml/min/mmHg, P = 0.02) and total excess blood flow (28 ± 9 vs. 24 ± 11 ml/100 ml, P < 0.01) were increased following sleep extension. The change in FVC and total excess blood flow were inversely correlated with the change in wake after sleep onset and TIB (both r = -0.62, P < 0.05), but not with sleep duration. These results demonstrate that extended time in bed accompanied by long sleep durations does not impair peripheral vascular function, but rather, may increase microvasculature vasodilatory capacity in midlife adults.

Women with a history of preeclampsia have preserved sensory nerve-mediated dilatation in the cutaneous microvasculature

NEW FINDINGS

What is the central question of this study? Are sensory nerve-mediated vasodilatation and the NO-dependent contribution to that response attenuated in the cutaneous microvasculature of women who have had preeclampsia? What is the main finding and its importance? Women who have had preeclampsia demonstrate attenuated microvascular endothelium-dependent dilatation compared to women with a history of uncomplicated pregnancy. However, there are no differences in sensory nerve-mediated vasodilatation between groups. This suggests that the neurogenic response is not altered following preeclampsia, and that the NO-dependent vasodilatation of the neurogenic response is not related to endothelium-dependent NO-mediated dilatation in these women.

ABSTRACT

Women who have had preeclampsia (PE) demonstrate microvascular endothelial dysfunction, mediated in part by reduced nitric oxide (NO)-dependent mechanisms. Localized heating of the skin induces a biphasic vasodilatation response: a sensory nerve-mediated initial peak, followed by a sustained endothelium-dependent plateau. We have previously shown that the endothelium-dependent plateau is attenuated in PE. However, it is unknown if the sensory nerve-mediated initial peak is similarly attenuated. Therefore, the purpose of this study was to examine the effect of PE history on sensory nerve-mediated vasodilatation and the NO-dependent contribution to that response. We hypothesized that PE would have an attenuated initial peak and a reduced NO-dependent contribution to that response compared to women with a history of normotensive pregnancy (healthy controls, HC). Nine HC (31 ± 4 years) and nine PE (28 ± 6 years) underwent a standard local heating protocol (42°C; 0.1°C s^-1 ). Two intradermal microdialysis fibres were placed in the skin of the ventral forearm for the continuous local delivery of lactated Ringer solution alone (control) or 15-mM N^G -nitro-l-arginine methyl ester for nitric oxide synthase (NOS) inhibition. Red blood cell flux was measured at each site by laser Doppler flowmetry (LDF). Cutaneous vascular conductance was calculated (CVC = LDF/mean arterial pressure) and normalized to maximum (%CVC_max ; 28-mM SNP + local heat 43°C). There were no differences in the initial peak between groups (HC: 79 ± 8 vs. PE: 80 ± 10%CVC_max ; P = 0.936). NOS inhibition attenuated the initial peak in both HC (57 ± 18% CVC_max ; P = 0.003) and PE (54 ± 10%CVC_max ; P = 0.002). However, there were no differences in the NO-dependent portion of the initial peak (HC: 23 ± 16 vs. PE: 24 ± 9%; P = 0.777). The local heating plateau (HC: 99 ± 4 vs. PE: 88 ± 7%CVC_max ; P = 0.001) and NO contribution to the plateau (HC: 31 ± 9 vs. PE: 17 ± 14%; P = 0.02) were attenuated in PE. There was no relation between NO-dependent dilatation in the initial peak and NO-dependent dilatation in the plateau across groups (R²  = 0.005; P = 0.943). Women who have had PE demonstrate attenuated microvascular endothelium-dependent dilatation. However, there are no differences in sensory nerve-mediated vasodilatation following PE, suggesting that the NO-dependent vasodilatation of the neurogenic response is not related to endothelium-dependent NO-mediated dilatation in these women.