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.

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.

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.

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.

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.

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.

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.

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.

Slow-Paced Breathing and Autonomic Function in People Post-stroke.

Purpose: To determine if acute slow breathing at 6 breaths/min would improve baroreflex sensitivity (BRS) and heart rate variability (HRV), and lower blood pressure (BP) in adults after stroke. Methods: Twelve individuals completed two randomized study visits where they performed a 15-min bout of breathing exercises at 6 breaths/min (slow) and at 12 breaths/min (control). Continuous BP and heart rate (HR) were measured throughout, and BRS, BRS response to elevations in blood pressure (BRSup), BRS response to depressions in blood pressure (BRSdown), and HRV were calculated and analyzed before (pre), during, and after (post) breathing exercises. Results: BRS increased from pre to post slow breathing by 10% (p = 0.012), whereas BRSup increased from pre to during slow breathing by 30% (p = 0.04). BRSdown increased from pre to post breathing for both breathing conditions (p < 0.05). HR (control: Δ - 4 ± 4; slow: Δ - 3 ± 4 beats/min, time, p < 0.01) and systolic BP (control: Δ - 0.5 ± 5; slow: Δ - 6.3 ± 8 mmHg, time, p < 0.01) decreased after both breathing conditions. Total power, low frequency power, and standard deviation of normal inter-beat intervals (SDNN) increased during the 6-breaths/min condition (condition × time, p < 0.001), whereas high frequency increased during both breathing conditions (time effect, p = 0.009). Conclusions: This study demonstrated that in people post-stroke, slow breathing may increase BRS, particularly BRSup, more than a typical breathing space; however, paced breathing at either a slow or typical breathing rate appears to be beneficial for acutely decreasing systolic BP and HR and increasing HRV.

Sarcopenic Obesity in Facioscapulohumeral Muscular Dystrophy.

BACKGROUND: Sarcopenic obesity has been observed in people with neuromuscular impairment, and is linked to adverse health outcomes. It is unclear, however, if sarcopenic obesity develops in adults with facioscapulohumeral muscular dystrophy (FSHD). METHODS: The purpose of this study was to determine if adults with FSHD meet criteria for sarcopenic obesity (appendicular lean mass index (ALMI) scores of < 7.26 or 5.45 kg/m2; % fat mass (FM) ≥ 28 or 40% in men/women). Ten people with FSHD (50 ± 11 years, 2 females) and ten age/sex-matched controls (47 ± 13 years, 2 females) completed one visit, which included a full-body dual-energy x-ray absorptiometry (DXA) scan. Regional and whole body total mass, fat mass (FM), and lean mass (LM) were collected and body mass index (BMI) and sarcopenia measures were computed. RESULTS: People with FSHD and controls had a similar whole body total mass (84.5 ± 12.9 vs. 81.8 ± 13.5 kg, respectively, p = 0.65). Though BMI was 2% lower in the FSHD group (p = 0.77), the % FM was 46% higher in FSHD, compared with controls (p < 0.01). In addition, ALM volume was 23% lower (p = 0.02) and ALMI was 27% lower in FSHD compared with controls (p < 0.01). Whole body LM trended to be lower in FSHD vs. controls (p = 0.05), and arm and leg LM were both lower in FSHD compared with controls (p < 0.05). Furthermore, the % LM was 18% lower in FSHD vs. controls (p < 0.01). FSHD participants exhibited greater total body FM (p < 0.01) and total leg FM (p < 0.01), but were similar in volume of total arm FM compared with controls (p = 0.09). CONCLUSION: Findings from this study suggest that people with FSHD, although similar in BMI and total body mass compared with controls, commonly meet the definition of sarcopenic obesity. Adults with co-existing FSHD and sarcopenic obesity may be at risk for significant impairments in quality of life, and encounter additional challenges in the management of FSHD manifestations.

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.

Skeletal Muscle Fatigability in Heart Failure.

Evidence suggests that heart failure (HF) patients experience skeletal muscle fatigability in the lower extremity during single-limb tasks. The contribution of skeletal muscle fatigability to symptoms of exercise intolerance (perceived fatigue and dyspnea) is relatively unclear. Symptomatic or 'perceived' fatigue is defined by the sensations of exhaustion or tiredness that patients experience either at rest or while performing a motor task. Although factors that contribute to symptoms of fatigue in patients with HF are multifactorial; the skeletal muscle likely plays a major role. Skeletal muscle fatigability, as opposed to symptomatic fatigue, is an objective measure of a reduction in muscle force or power or reduced ability of the muscles to perform over time. Indeed, evidence suggests that patients with HF experience greater skeletal muscle fatigability which may contribute to a diminution in motor performance and the overall symptomatology that is hallmark of exercise intolerance in HF. This review will discuss (1) skeletal muscle fatigability in patients with HF, (2) the mechanisms contributing to locomotor skeletal muscle fatigability in HF and (3) the relationship of fatigability to symptoms of perceived fatigue and exercise intolerance in HF patients. Evidence suggests that cardiac dysfunction alone does not contribute to exercise intolerance. Therefore, mechanisms of skeletal muscle fatigability and their contribution to symptoms of fatigue and exercise intolerance, is an increasingly important consideration as we develop rehabilitative strategies for improving motor performance and functional capacity in patients with HF.

VE/VCO2 slope in lean and overweight women and its relationship to lean leg mass.

Ventilation/carbon dioxide production (VE/VCO2slope) is used clinically to determine cardiorespiratory fitness and morbidity in heart failure (HF). Previously, we demonstrated that lower lean leg mass is associated with high VE/VCO2slope during exercise in HF. In healthy individuals, we evaluated 1) whether VE/VCO2slope differed between lean and overweight women and 2) the relationship between lean leg mass and VE/VCO2slope in overweight sedentary (OWS), overweight trained (OWTR) and lean, trained (LTR) women. METHODS: Gas exchange and ventilation were collected during a treadmill peak oxygen uptake test (VO2peak) in 40 women [26 OWS (29 ±â€¯7 yrs., mean ±â€¯SD), 7 OWTR (33 ±â€¯5 yrs) and 7 LTR (26 ±â€¯6 yrs)]. Body composition was measured by dual X-ray absorptiometry. RESULTS: VO2peak was highest in LTR (46.6 ±â€¯8 ml/kg/min) compared with OWTR (38.1 ±â€¯4.9 ml/kg/min) and OWS women (25.3 ±â€¯4.8 ml/kg/min, p < 0.05). Lean leg mass was highest in OWTR and lowest in LTR women (p < 0.05). VE/VCO2slope was similar between groups (p > 0.05). Higher lean leg mass was associated with lower VE/VCO2slope in overweight women (OWS + OWTR: r = -0.55, p < 0.001), contrasting with higher VE/VCO2slope in LTR women (r = 0.86, p < 0.001). CONCLUSIONS: These findings suggest VE/VCO2slope may not differentiate between low and high cardiorespiratory fitness in healthy individuals and muscle mass may play a role in determining the VE/VCO2slope, independent of disease.

Age-Related Decline of Wrist Position Sense and its Relationship to Specific Physical Training.

Perception of limb and body positions is known as proprioception. Sensory feedback, especially from proprioceptive receptors, is essential for motor control. Aging is associated with a decline in position sense at proximal joints, but there is inconclusive evidence of distal joints being equally affected by aging. In addition, there is initial evidence that physical activity attenuates age-related decline in proprioception. Our objectives were, first, to establish wrist proprioceptive acuity in a large group of seniors and compare their perception to young adults, and second, to determine if specific types of training or regular physical activity are associated with preserved wrist proprioception. We recruited community-dwelling seniors (n = 107, mean age, 70 ± 5 years, range, 65-84 years) without cognitive decline (Mini Mental State Examination-brief version ≥13/16) and young adult students (n = 51, mean age, 20 ± 1 years, range, 19-26 years). Participants performed contralateral and ipsilateral wrist position sense matching tasks with a bimanual wrist manipulandum to a 15° flexion reference position. Systematic error or proprioceptive bias was computed as the mean difference between matched and reference position. The respective standard deviation over five trials constituted a measure of random error or proprioceptive precision. Current levels of physical activity and previous sport, musical, or dance training were obtained through a questionnaire. We employed longitudinal mixed effects linear models to calculate the effects of trial number, sex, type of matching task and age on wrist proprioceptive bias and precision. The main results were that relative proprioceptive bias was greater in older when compared to young adults (mean difference: 36% ipsilateral, 88% contralateral, p < 0.01). Proprioceptive precision for contralateral but not for ipsilateral matching was smaller in older than in young adults (mean difference: 38% contralateral, p < 0.01). Longer years of dance training were associated with smaller bias during ipsilateral matching (p < 0.01). Other types of training or physical activity levels did not affect bias or precision. Our findings demonstrate that aging is associated with a decline in proprioceptive bias in distal arm joints, but age does not negatively affect proprioceptive precision. Further, specific types of long-term dance related training may attenuate age-related decline in proprioceptive bias.

Influence of Inhaled Amiloride on Lung Fluid Clearance in Response to Normobaric Hypoxia in Healthy Individuals.

Wheatley, Courtney M., Sarah E. Baker, Bryan J. Taylor, Manda L. Keller-Ross, Steven C. Chase, Alex R. Carlson, Robert J. Wentz, Eric M. Snyder, and Bruce D. Johnson. Influence of inhaled amiloride on lung fluid clearance in response to normobaric hypoxia in healthy individuals. High Alt Med Biol 18:343-354, 2017. AIM: To investigate the role of epithelial sodium channels (ENaC) on lung fluid clearance in response to normobaric hypoxia, 20 healthy subjects were exposed to 15 hours of hypoxia (fraction of inspired oxygen [FiO2] = 12.5%) on two randomized occasions: (1) inhaled amiloride (A) (1.5 mg/5 mL saline); and (2) inhaled saline placebo (P). Changes in lung fluid were assessed through chest computed tomography (CT) for lung tissue volume (TV), and the diffusion capacity of the lungs for carbon monoxide (DLCO) and nitric oxide (DLNO) for pulmonary capillary blood volume (VC). Extravascular lung water (EVLW) was derived as TV-VC and changes in the CT attenuation distribution histograms were reviewed. RESULTS: Normobaric hypoxia caused (1) a reduction in EVLW (change from baseline for A vs. P, -8.5% ± 3.8% vs. -7.9% ± 5.2%, p < 0.05), (2) an increase in VC (53.6% ± 28.9% vs. 53.9% ± 52.3%, p < 0.05), (3) a small increase in DLCO (9.6% ± 29.3% vs. 9.9% ± 23.9%, p > 0.05), and (4) CT attenuation distribution became more negative, leftward skewed, and kurtotic (p < 0.05). CONCLUSION: Acute normobaric hypoxia caused a reduction in lung fluid that was unaffected by ENaC inhibition through inhaled amiloride. Although possible amiloride-sensitive ENaC may not be necessary to maintain lung fluid balance in response to hypoxia, it is more probable that normobaric hypoxia promotes lung fluid clearance rather than accumulation for the majority of healthy individuals. The observed reduction in interstitial lung fluid means alveolar fluid clearance may not have been challenged.