Sleep disturbance and sympathetic neural reactivity in postmenopausal females.

Sleep disturbance, one of the most common menopausal symptoms, contributes to autonomic dysfunction and is linked to hypertension and cardiovascular risk. Longitudinal studies suggest that hyperreactivity of blood pressure (BP) to a stressor can predict the future development of hypertension. It remains unknown if postmenopausal females who experience sleep disturbance (SDG) demonstrate greater hemodynamic and sympathetic neural hyperreactivity to a stressor. We hypothesized that postmenopausal females with reported sleep disturbance would exhibit increased hemodynamic and sympathetic reactivity to a stressor compared with postmenopausal females without sleep disturbance (non-SDG). Fifty-five postmenopausal females (age, 62 ± 4 yr old; SDG, n = 36; non-SDG; n = 19) completed two study visits. The Menopause-Specific Quality of Life Questionnaire (MENQOL) was used to assess the presence of sleep disturbance (MENQOL sleep scale, ≥2 units). Beat-to-beat BP (finger plethysmography), heart rate (HR; electrocardiogram), and muscle sympathetic nerve activity (MSNA; microneurography; SDG, n = 25; non-SDG, n = 15) were continuously measured during a 10-min baseline and 2-min stressor (cold pressor test; CPT) in both groups. Menopause age and body mass index were similar between groups (P > 0.05). There were no differences between resting BP, HR, or MSNA (P > 0.05). HR and BP reactivity were not different between SDG and non-SDG (P > 0.05). In contrast, MSNA reactivity had a more rapid increase in the first 30 s of the CPT in the SDG (burst incidence, Δ10.2 ± 14.8 bursts/100 hb) compared with the non-SDG (burst incidence, Δ4.0 ± 14.8 bursts/100 hb, time × group, P = 0.011). Our results demonstrate a more rapid sympathetic neural reactivity to a CPT in postmenopausal females with perceived sleep disturbance, a finding that aligns with and advances recent evidence that sleep disturbance is associated with sympathetic neural hyperactivity in postmenopausal females.NEW & NOTEWORTHY This is the first study to demonstrate that muscle sympathetic nerve activity (MSNA) to a cold pressor test is augmented in postmenopausal females with perceived sleep disturbance. The more rapid increase in MSNA reactivity during the cold pressor test in the sleep disturbance group was present despite similar increases in the perceived pain levels between groups. Baseline MSNA burst incidence and burst frequency, as well as blood pressure and heart rate, were similar between the sleep disturbance and nonsleep disturbance groups.

Blood pressure and muscle sympathetic nerve activity are associated with trait anxiety in humans.

Chronic anxiety is prevalent and associated with an increased risk of cardiovascular disease. Prior studies that have reported a relationship between muscle sympathetic nerve activity (MSNA) and anxiety have focused on participants with anxiety disorders and/or metabolic syndrome. The present study leverages a large cohort of healthy adults devoid of cardiometabolic disorders to examine the hypothesis that trait anxiety severity is positively associated with resting MSNA and blood pressure. Resting blood pressure (BP) (sphygmomanometer and finger plethysmography), MSNA (microneurography), and heart rate (HR; electrocardiogram) were collected in 88 healthy participants (52 males, 36 females, 25 ± 1 yr, 25 ± 1 kg/m2). Multiple linear regression was performed to assess the independent relationship between trait anxiety, MSNA, resting BP, and HR while controlling for age and sex. Trait anxiety was significantly correlated with systolic arterial pressure (SAP; r = 0.251, P = 0.018), diastolic arterial pressure (DAP; r = 0.291, P = 0.006), mean arterial pressure (MAP; r = 0.328, P = 0.002), MSNA burst frequency (BF; r = 0.237, P = 0.026), and MSNA burst incidence (BI; r = 0.225, P = 0.035). When controlling for the effects of age and sex, trait anxiety was independently associated with SAP (ß = 0.206, P = 0.028), DAP (ß = 0.317, P = 0.002), MAP (ß = 0.325, P = 0.001), MSNA BF (ß = 0.227, P = 0.030), and MSNA BI (ß = 0.214, P = 0.038). Trait anxiety is associated with increased blood pressure and MSNA, demonstrating an important relationship between anxiety and autonomic blood pressure regulation.NEW & NOTEWORTHY Anxiety is associated with development of cardiovascular disease. Although the sympathetic nervous system is a likely mediator of this relationship, populations with chronic anxiety have shown little, if any, alteration in resting levels of directly recorded muscle sympathetic nerve activity (MSNA). The present study is the first to reveal an independent relationship between trait anxiety, resting blood pressure, and MSNA in a large cohort of healthy males and females devoid of cardiometabolic comorbidities.

A review of the historical use of sex as a biological variable in the American Journal of Physiology-Heart and Circulatory Physiology.

Despite National Institute of Health (NIH) mandates requiring sex as a biological variable (SABV), female underrepresentation persists in research, driving the American Journal of Physiology-Heart and Circulatory Physiology (Am J Physiol-Heart Circ) to publish SABV expectations in 2021. To determine progress within the Am J Physiol-Heart Circ, this mini-review evaluated SABV during the first 6 mo of each decade from 1980 to 2020, and 2019, to mitigate pandemic influence. Of the 1,205 articles published, 1,087 articles were included in this review (articles without original research subjects were excluded), of which 72.9% identified subjects. There were consistently fewer female human participants than males, except within 2019 (1980: females n = 3, males n = 5; 1990: females n = 70, males n = 199; 2000: females n = 305, males n = 355; 2010: females n = 186, males n = 472; 2019: females n = 1,695, males n = 1,550; 2020: females n = 1,157, males n = 1,222) and fewer female animals than males (1980: females n = 58, males n = 1,291; 1990: females n = 447, males n = 2,628; 2000: females n = 590, males n = 3,083; 2010: females n = 663, males n = 4,517; 2019: females n = 338, males n = 1,340; 2020: females n = 1,372, males n = 1,973). Only 16 (12.3%) articles including humans discussed SABV from 1980 to 2020. There are persistent SABV disparities within Am J Physiol-Heart Circ with some improvements in recent years. It is imperative that organizations such as the American Physiological Society and NIH foster an expectation of SABV as the norm, not the exception.

Sleep efficiency and PTSD symptom severity predict microvascular endothelial function and arterial stiffness in young, trauma-exposed women.

Posttraumatic stress disorder (PTSD) is linked to sleep disturbances and significantly higher risk of developing cardiovascular disease (CVD). Furthermore, vascular dysfunction and sleep are independently associated with CVD. Uncovering the link between PTSD symptom severity, sleep disturbances, and vascular function could shine a light on mechanisms of CVD risk in trauma-exposed young women. The purpose of the present study was to investigate the individual and combined effects of sleep efficiency and PTSD symptom severity on vascular function. We recruited 60 otherwise healthy women [age, 26 ± 7 yr and body mass index (BMI), 27.7 ± 6.5 kg/m2] who had been exposed to trauma. We objectively quantified sleep efficiency (SE) using actigraphy, microvascular endothelial function via Framingham reactive hyperemia index (fRHI), and arterial stiffness via pulse-wave velocity (PWV). PTSD symptom severity was assessed using the PTSD checklist for fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) (PCL5). PWV was correlated with age (r = 0.490, P < 0.001) and BMI (r = 0.484, P < 0.001). In addition, fRHI was positively correlated with SE (r = 0.409, P = 0.001) and negatively correlated with PTSD symptoms (r = -0.382, P = 0.002). To explore the predictive value of SE and PTSD symptoms on PWV and fRHI, we conducted two multivariate linear regression models. The model predicting PWV was significant (R2 = 0.584, P < 0.001) with age, BMI, blood pressure, and SE emerging as predictors. Likewise, the model predicting fRHI was significant (R2 = 0.360, P < 0.001) with both PTSD symptoms and SE as significant predictors. Our results suggest that although PTSD symptoms mainly impact microvascular endothelial function, sleep efficiency is additionally associated with arterial stiffness in young trauma-exposed women, after controlling for age and BMI.NEW & NOTEWORTHY This is the first study to investigate the individual and combined impacts of objective sleep and PTSD symptoms severity on arterial stiffness and microvascular endothelial function in young premenopausal women. We report that in young trauma-exposed women, although low sleep efficiency is associated with overall vascular function (i.e., microvascular endothelial function and arterial stiffness), the severity of PTSD symptoms is specifically associated with microvascular endothelial function, after accounting for age and body mass index.

Vasomotor symptoms of menopause, autonomic dysfunction, and cardiovascular disease.

Cardiovascular disease (CVD), the leading cause of death among US adults, is more prevalent in menopausal females compared with age-matched males. Vasomotor symptoms of menopause (VMS; hot flashes/flushes and night sweats) are common among females undergoing menopausal transition and have been associated with elevated blood pressure (BP) and increased CVD risk. Autonomic dysregulation of BP has been posited as a contributing factor to the elevated CVD risk in menopausal females with VMS. This review includes 1) a brief overview of the relationship between VMS and CVD, 2) mechanisms of hot flushes and their potential impact on short- and long-term BP regulation, and 3) how the disruption of autonomic function associated with VMS might provide a mechanistic pathway to CVD development. Finally, this review will highlight knowledge gaps and future directions toward better understanding of hot flush physiology and VMS contributions to CVD.

Cardiovascular Effects of Transcranial Direct Current Stimulation and Bimanual Training in Children With Cerebral Palsy.

PURPOSE: To determine the influence of combined transcranial direct current stimulation (tDCS) to the motor cortex (M1) and bimanual training on cardiovascular function in children with cerebral palsy (CP). METHODS: Mean arterial pressure (MAP), heart rate (HR), and HR variability (HRV) were measured immediately before and after 20 minutes of cathodal tDCS to contralesional M1 and bimanual training on days 1, 6, and 10 of a 10-day trial in 8 participants (5 females, 7-19 years). RESULTS: Baseline MAP and HR were similar across days (93 ± 10 mm Hg and 90 ± 10 bpm, P > .05). MAP was similar from baseline to postintervention across all 3 days. Systolic pressure, diastolic pressure, nor HR significantly changed. HRV was not influenced by the 10-day intervention. CONCLUSIONS: Combined cathodal tDCS to M1 and bimanual training does not influence autonomic and cardiovascular function in children with CP due to perinatal stroke.

Locomotor muscle group III/IV afferents constrain stroke volume and contribute to exercise intolerance in human heart failure.

KEY POINTS: Heart failure patients with reduced ejection fraction (HFrEF) exhibit severe limitations in exercise capacity ( V̇O2 peak). One of the primary peripheral mechanisms suggested to underlie exercise intolerance in HFrEF is excessive locomotor muscle group III/IV afferent feedback; however, this has never been investigated in human heart failure. HFrEF patients and controls performed an incremental exercise test to volitional exhaustion to determine V̇O2 peak with lumbar intrathecal fentanyl or placebo. During exercise, cardiac output, leg blood flow and radial artery and femoral venous blood gases were measured. With fentanyl, compared with placebo, patients with HFrEF achieved a higher peak workload, V̇O2 peak, cardiac output, stroke volume and leg blood flow. These findings suggest that locomotor muscle group III/IV afferent feedback in HFrEF leads to increased systemic vascular resistance, which constrains stroke volume, cardiac output and O2 delivery thereby impairing V̇O2 peak and thus exercise capacity. ABSTRACT: To better understand the underlying mechanisms contributing to exercise limitation in heart failure with reduced ejection fraction (HFrEF), we investigated the influence of locomotor muscle group III/IV afferent inhibition via lumbar intrathecal fentanyl on peak exercise capacity ( V̇O2 peak) and the contributory mechanisms. Eleven HFrEF patients and eight healthy matched controls were recruited. The participants performed an incremental exercise test to volitional exhaustion to determine V̇O2 peak with lumbar intrathecal fentanyl or placebo. During exercise, cardiac output and leg blood flow ( Q̇L ) were measured via open-circuit acetylene wash-in technique and constant infusion thermodilution, respectively. Radial artery and femoral venous blood gases were measured. V̇O2 peak was 15% greater with fentanyl compared with placebo for HFrEF (P < 0.01), while no different in the controls. During peak exercise with fentanyl, cardiac output was 12% greater in HFrEF secondary to significant decreases in systemic vascular resistance and increases in stroke volume compared with placebo (all, P < 0.01). From placebo to fentanyl, leg V̇O2 , Q̇L and O2 delivery were greater for HFrEF during peak exercise (all, P < 0.01), but not control. These findings indicate that locomotor muscle group III/IV afferent feedback in patients with HFrEF leads to increased systemic vascular resistance, which constrains stroke volume, cardiac output and O2 delivery, thereby impairing V̇O2 peak and thus exercise capacity. These findings have important clinical implications as V̇O2 peak is highly predictive of morbidity and mortality in HF.

Exercise Intolerance in Heart Failure: Central Role for the Pulmonary System.

We propose that abnormalities of the pulmonary system contribute significantly to the exertional dyspnea and exercise intolerance observed in patients with chronic heart failure. Interventions designed to address the deleterious pulmonary manifestations of heart failure may, therefore, yield promising improvements in exercise tolerance in this population.

Influence of the metaboreflex on arterial blood pressure in heart failure patients.

BACKGROUND: Feedback from active locomotor muscles contributes to the exercise pressor response in healthy humans, and is thought to be more prominent in heart failure (HF). The purpose of this study was to examine the influence of metaboreflex stimulation on arterial pressure in HF. METHODS: Eleven HF patients (51 ± 5 years, New York Heart Association Class I/II, left ventricular ejection fraction 32 ± 3%) and 11 controls (42 ± 3 years) were recruited. Participants completed two exercise sessions on separate days: (1) symptom limited graded exercise test; and (2) constant work rate cycling (60% peak oxygen consumption,V˙O2) for 4 minutes with 2 minutes passive recovery. Recovery was randomized to normal or locomotor muscle regional circulatory occlusion (RCO). Mean arterial pressure (MAP), systolic pressure (SBP), diastolic pressure, heart rate (HR) and V˙O2 were measured at rest, end-exercise and recovery. O2 pulse (V˙O2/HR) and the rate pressure product (RPP = HR × SBP) were calculated. RESULTS: In response to RCO, mean arterial pressure and SBP increased in HF compared with CTLs (6.8 ± 5.8% vs -3.0 ± 7.8%, P < .01 and 3.4 ± 6.4% vs -12.7 ± 10.4%, P < .01, respectively), with no difference in diastolic pressure (P = .61). HF patients had a smaller reduction in HR and RPP, but also displayed a larger decrease in O2 pulse consequent to locomotor metaboreflex stimulation (P < .05, for all). CONCLUSION: RCO resulted in a markedly increased pressor response in HF relative to controls, due primarily to an increase of SBP and attenuated cardiac recovery as noted by the persistent elevation in HR.

Blunted cardiovascular responses to exercise by inhibiting afferent feedback via spinal cord stimulation in heart failure.

This case study investigated the impact of SCS on alterations in blood pressure during constant-load exercise in a female patient with heart failure. Three different SCS frequencies [No SCS (~0 Hz), Low SCS (~100 Hz), and High SCS (~1000 Hz)] with and without ischaemic stimulation of the legs (cuffs) were randomly applied during constant-load exercise. To determine cardiovascular and ventilatory responses to exercise following SCS frequencies, BP, heart rate (HR), and respiratory gas exchange were measured. This experiment was duplicated in visit 1 and visit 2 with a random application of SCS frequency order and the data were averaged. There were no significant differences among three frequencies with no leg ischaemia. However, High SCS demonstrated lower BP, HR, and respiratory gas exchange relative to No SCS and Low SCS. SCS may be effective in improving cardiovascular and ventilatory responses in HF and high-frequency stimulation provides more clinical benefit; however, further studies are needed.

Using the RE-AIM framework to evaluate physical activity-based fall prevention interventions in older adults with chronic conditions: A systematic review.

Falls are a serious public health problem, especially for older adults with chronic conditions. The purpose of this systematic review was to evaluate the translational potential of physical activity-based balance interventions for older adults with common chronic conditions guided by the Reach, Effectiveness/Efficacy, Adoption, Implementation, and Maintenance (RE-AIM) framework. Databases were searched (2011-2021) to identify studies with physical activity-based fall prevention interventions for older adults with chronic conditions. Data were collected using the RE-AIM coding guide and Mixed Methods Appraisal Tool for evidence quality. The search yielded 122 articles, of which 14 distinct studies were included. The most reported RE-AIM dimensions across the studies were Reach (46.2%) and Implementation (40.5%), with Effectiveness/Efficacy (29.4%), Adoption (2.0%), and Maintenance (5.4%) being the least reported. Studies were largely conducted in controlled research environments with minimal staff involvement and without long-term follow-up periods. While studies found that physical activity-based programs were effective in improving balance, information on representativeness and adoption/maintenance of programs was lacking. Studies included sufficient details about the intervention (content, dosage, progression). External validity RE-AIM indicators were reported less frequently than internal validity indicators. The studies were of moderate quality overall. Studies often lacked information on indicators critical for understanding how to implement these programs. This review signals the need to investigate the translation of these interventions from controlled research settings to clinical settings to improve the public impact of fall prevention for this population.

Falls are a serious public health problem, especially for older adults with chronic diseases who have a higher risk of falling. For this review paper, we gathered similar research articles that looked at the effects of balance exercise programs in older adults with a variety of chronic diseases and reviewed how likely they could be used in real-world settings using a guide. We found fourteen studies that met our criteria. The most common elements that authors included in their reports were how research subjects were identified and details about the exercise program design/delivery. The least common elements were the scientific outcomes of the program, how/where the program was incorporated, and the long-term effects of the program. While these balance exercise programs for older adults with chronic diseases were successful in these individual research studies, this general area of fall research is somewhat underdeveloped. Researchers should put more consideration into surroundings where these programs could take place and study how these programs could be successful in real-world settings long-term.

Perceptions, Benefits, and Use of Complementary and Integrative Therapies to Treat Menopausal Symptoms: A Pilot Study.

Background: Menopause symptoms can be debilitating, and the use of menopausal hormone therapy (MHT) has declined significantly since the Women's Health Initiative. Materials and Methods: We surveyed 508 peri- and postmenopausal females to determine (1) the use of complementary and integrative therapies (CIT), MHT; and pharmacotherapies; (2) the perceptions, perceived benefits/risks of CIT, MHT; and pharmacotherapy use; and (3) factors associated with CIT and MHT use for menopause symptom treatment. Results: The majority of respondents used CIT to treat menopause symptoms based on physician recommendation and research studies. Treatments that were perceived as most beneficial included exercise, mind-body therapies, diet, and spiritual practices, with exercise and mind-body therapies chosen to treat the most common symptoms of sleep disturbances, depressive mood, and anxiety. Higher education level was the main predictive variable for choosing exercise (odds ratio [OR] = 1.27, p = 0.02) and mind-body therapies (OR = 1.57, p = 0.02) to treat menopausal symptoms. Perceptions, beliefs, and use of different CIT by primarily white, affluent, and educated peri- and postmenopausal females to treat menopause symptoms, including sleep disturbances, depression, and anxiety, are driven by conversations with physicians and evidence-based research. Conclusion: These findings reinforce the necessity for both additional research in more diverse populations, as well as comprehensive, individualized personalized care from an interdisciplinary team that considers the best options available for all female patients.

Corrigendum: Sarcopenic Obesity in Facioscapulohumeral Muscular Dystrophy.

[This corrects the article DOI: 10.3389/fphys.2020.01008.].

Exercise Intolerance in Facioscapulohumeral Muscular Dystrophy.

PURPOSE: Determine 1) if adults with facioscapulohumeral muscular dystrophy (FSHD) exhibit exercise intolerance and 2) potential contributing mechanisms to exercise intolerance, specific to FSHD. METHODS: Eleven people with FSHD (47 ± 13 yr, 4 females) and 11 controls (46 ± 13 yr, 4 females) completed one visit, which included a volitional peak oxygen consumption (V̇O2peak) cycling test. Breath-by-breath gas exchange, ventilation, and cardiovascular responses were measured at rest and during exercise. The test featured 3-min stages (speed, 65-70 rpm) with incremental increases in intensity (FSHD: 20 W per stage; control: 40-60 W per stage). Body lean mass (LM (kg, %)) was collected via dual-energy x-ray absorptiometry. RESULTS: V̇O2peak was 32% lower (24.5 ± 9.7 vs 36.2 ± 9.3 mL·kg-1·min-1, P < 0.01), and wattage was 55% lower in FSHD (112.7 ± 56.1 vs 252.7 ± 67.7 W, P < 0.01). When working at a relative submaximal intensity (40% of V̇O2peak), wattage was 55% lower in FSHD (41.8 ± 30.3 vs 92.7 ± 32.6 W, P = 0.01), although ratings of perceived exertion (FSHD: 11 ± 2 vs control: 10 ± 3, P = 0.61) and dyspnea (FSHD: 3 ± 1 vs control: 3 ± 2, P = 0.78) were similar between groups. At an absolute intensity (60 W), the rating of perceived exertion was 63% higher (13 ± 3 vs 8 ± 2, P < 0.01) and dyspnea was 180% higher in FSHD (4 ± 2 vs 2 ± 2, P < 0.01). V̇O2peak was most strongly correlated with resting O2 pulse in controls (P < 0.01, r = 0.90) and percent leg LM in FSHD (P < 0.01, r = 0.88). Among FSHD participants, V̇O2peak was associated with self-reported functionality (FSHD-HI score; activity limitation: P < 0.01, r = -0.78), indicating a strong association between perceived and objective impairments. CONCLUSIONS: Disease-driven losses of LM contribute to exercise intolerance in FSHD, as evidenced by a lower V̇O2peak and elevated symptoms of dyspnea and fatigue during submaximal exercise. Regular exercise participation may preserve LM, thus providing some protection against exercise tolerance in FSHD.

Active Rehabilitation in a Patient During and After Venovenous Extracorporeal Membrane Oxygenation With a Diagnosis of COVID-19: A Case Report.

PURPOSE: The coronavirus disease-2019 (COVID-19) pandemic has resulted in an influx of critically ill patients requiring mechanical ventilation, some receiving venovenous (VV) extracorporeal membrane oxygenation (ECMO). The benefits of early mobility while undergoing ECMO have been previously documented. However, the COVID-19 pandemic has presented physical therapists with novel challenges, balancing the risk of a widespread shortage of personal protective equipment (PPE) with the benefits of early mobility for patients on ECMO. The purpose of this case study is to report the successful rehabilitation of a critically ill patient with COVID-19 undergoing VV ECMO. METHODS: This is a case description of a 38-year-old man who presented to the hospital with COVID-19 and subsequent intubation and cannulation for VV ECMO. Physical therapy was initiated while the patient remained critically ill on VV ECMO. Focused coordination and education were employed to limit PPE usage by limiting the number of essential staff/therapists that entered the room as well as changing the frequency of therapy sessions dependent on how the patient was progressing functionally. RESULTS: On VV ECMO day 11, he was able to sit up and perform a sit-to-stand. ECMO decannulation occurred on hospital day 14 with extubation on hospital day 18. The patient progressed functionally while quarantined in the room until he was discharged home with supplemental oxygen after spending 29 days in the hospital. CONCLUSION: This case study demonstrates the clinical decision-making used to provide physical therapy services for a critically ill patient with COVID-19. High-level team coordination resulted in limiting the use of PPE as well as reducing staff exposure frequency during rehabilitation. Despite his severe critical illness, the patient was successfully discharged home within 30 days.

Baroreflex sensitivity in facioscapulohumeral muscular dystrophy.

Facioscapulohumeral muscular dystrophy (FSHD), a common form of muscular dystrophy, is caused by a genetic mutation that alters DUX4 gene expression. This mutation contributes to significant skeletal muscle loss. Although it is suggested that cardiac muscle may be spared, people with FSHD have demonstrated autonomic dysregulation. It is unknown if baroreflex function, an important regulator of blood pressure (BP), is impaired in people with FSHD. We examined if baroreflex sensitivity (BRS) is blunted in patients with FSHD. Thirty minutes of resting BP, heart rate, and cardiovagal BRS were measured in 13 patients with FSHD (age: 50 ± 13 years, avg ± SD) and 17 sex- and age-matched controls (age: 47 ± 14 years, p > 0.05). People with FSHD were less active (Activity Metabolic Index, AMI) (FSHD: 24 ± 30; controls: 222 ± 175 kcal/day; p < 0.001) but had a similar body mass index compared with controls (FSHD: 27 ± 4; controls: 27 ± 4 kg/m2 ; p > 0.05). BRSup (hypertensive response), BRSdown (hypotensive response), and total BRS were similar between groups (BRSup: FSHD: 12 ± 8; controls: 12 ± 5 ms/mmHg; BRSdown: FSHD: 10 ± 4; controls: 13 ± 6 ms/mmHg; BRS: FSHD: 14 ± 9; controls: 13 ± 6 ms/mmHg; p > 0.05). Mean arterial pressure was similar between groups (FSHD: 96 ± 7; controls: 91 ± 6mmHg). Individuals with FSHD had an elevated heart rate compared with controls (FSHD: 65 ± 8; controls: 59 ± 8 BPM; p = 0.03), but when co-varied for AMI, this relationship disappeared (p = 0.39). These findings suggest that BRS is not attenuated in people with FSHD, but an elevated heart rate may be due to low physical activity levels, a potential consequence of limited mobility.

Influence of locomotor muscle group III/IV afferents on cardiovascular and ventilatory responses in human heart failure during submaximal exercise.

The purpose of this study is to determine the influence of locomotor muscle group III/IV afferent inhibition on central and peripheral hemodynamics at multiple levels of submaximal cycling exercise in patients with heart failure with reduced ejection fraction (HFrEF). Eleven patients with HFrEF and nine healthy matched controls were recruited. The participants performed a multiple stage [i.e., 30 W, 50%peak workload (WL), and a workload eliciting a respiratory exchange ratio (RER) of ∼1.0] exercise test with lumbar intrathecal fentanyl (FENT) or placebo (PLA). Cardiac output ([Formula: see text]tot) was measured via open-circuit acetylene wash-in technique and stroke volume was calculated. Leg blood flow ([Formula: see text]l) was measured via constant infusion thermodilution and leg vascular conductance (LVC) was calculated. Radial artery and femoral venous blood gases were measured. For HFrEF, stroke volume was higher at the 30 W (FENT: 110 ± 21 vs. PLA: 100 ± 18 mL), 50%peak WL (FENT: 113 ± 22 vs. PLA: 103 ± 23 mL), and RER = 1.0 (FENT: 119 ± 28 vs. PLA: 110 ± 26 mL) stages, whereas heart rate and systemic vascular resistance were lower with fentanyl than with placebo (all, P < 0.05). [Formula: see text]tot in HFrEF and [Formula: see text]tot, stroke volume, and heart rate in controls were not different between fentanyl and placebo (all, P > 0.19). During submaximal exercise, controls and patients with HFrEF exhibited increased leg vascular conductance (LVC) with fentanyl compared with placebo (all, P < 0.04), whereas no differences were present in [Formula: see text]l or O2 delivery with fentanyl (all, P > 0.20). Taken together, these findings provide support for locomotor muscle group III/IV afferents playing a role in integrative control mechanisms during submaximal cycling exercise in patients with HFrEF and older controls.NEW & NOTEWORTHY Patients with HFrEF exhibit severe exercise intolerance. One of the primary peripheral mechanisms contributing to exercise intolerance in patients with HFrEF is locomotor muscle group III/IV afferent feedback. However, it is unknown whether these afferents impact the central and peripheral responses during submaximal cycling exercise. Herein, we demonstrate that inhibition of locomotor muscle group III/IV afferent feedback elicited increases in stroke volume during submaximal exercise in HFrEF, but not in healthy controls.

Resting metabolic rate in adults with facioscapulohumeral muscular dystrophy.

This study aimed to determine whether resting metabolic rate (RMR) is altered in adults with facioscapulohumeral muscular dystrophy (FSHD). Eleven people with FSHD (51 ± 12yrs, 2 females) and 11 controls (48 ± 14 yrs, 2 females) completed 1 visit, including 30-minutes of indirect calorimetry and dual-energy X-ray absorptiometry (DXA) scanning. RMR was calculated from resting oxygen consumption/carbon dioxide production; regional/whole-body fat mass and lean mass were collected from the DXA scan. Absolute RMR was 15% lower in FSHD (p = 0.04); when normalized to regional/local lean mass, no differences in RMR were observed (p > 0.05). Absolute RMR was correlated with total lean mass for all participants combined (p < 0.01, r = 0.70, males only: p < 0.01, r = 0.81) and when analyzed separately (FSHD males: p = 0.001, r = 0.92 and control males: p = 0.004, r = 0.85). Whole-body lean mass was 16% lower in FSHD and leg, arm and appendicular lean mass were lower in FSHD (p < 0.05 for all), though trunk lean mass was not (p = 0.15). Whole-body fat mass was 45% higher in FSHD, with greater leg fat mass (p = 0.01), but not trunk or arm fat mass (p > 0.05 for both). When RMR was expressed relative to lean body mass, no differences in RMR were found, indicating that the lower levels of lean mass observed in FSHD patients likely contribute to the lower absolute RMR values. Novelty: RMR is lower among people with FSHD, as compared with controls. The reduced RMR among people with FSHD is due to disease-related loss in muscle mass and likely related to lower physical activity and/or exercise levels.

Menstrual phase does not influence ventilatory responses to group III/IV afferent signaling in eumenorrheic young females.

Estrogen can reduce sympathetic activity, but its effects on minute ventilation (VE) with group III/IV afferent activation remain unclear. This study examined the influence of estrogen on VE during lower-extremity exercise with group III/IV activation. Females completed two identical visits in follicular and ovulatory menstrual phases. Nine participants (age 25 ± 4 years) performed three minutes of baseline steady-state cycle ergometry and then group III/IV afferents were further activated with proximal thigh cuffs inflated to 20, 60, and 100 mmHg (randomized) for two minutes and five minutes of cycling between each occlusion. Metaboreflex was isolated by post-exercise circulatory occlusion. Ventilation was measured continuously and rating of perceived exertion (RPE) was recorded for each stage. During rest and exercise, VE (p < 0.001) and tidal volume (VT) (p = 0.033) were higher in the follicular than ovulatory phase. Minute ventilation, VT, and respiratory rate (RR) with ergoreflex and metaboreflex activation were similar across phases. With cuff occlusion of 100 mmHg, VE increased from baseline by 26.3 ± 7.0 L/min in the follicular phase (p < 0.001) and by 25.3±7.7 L/min in the ovulatory phase (p < 0.001), with no difference between phases (p> 0.05); RR and VT increased similarly with occlusion, also with no phase differences. In eumenorrheic females, menstrual phase influences ventilation but not ventilatory responses to group III/IV isolation.