Lower VO2 Research Articles

Device-measured physical activity and cardiovascular disease risk in adolescent childhood cancer survivors. A physical activity in childhood cancer survivors (PACCS) study.

ObjectivesWe aimed to compare cardiovascular disease (CVD) risk factors in childhood cancer survivors (CCS) with age- and sex-stratified reference material and examine the association between physical activity (PA) intensities and CVD risk factors in CCS.Materials and methodsWithin the cross-sectional, multicenter Physical Activity in Childhood Cancer Survivors (PACCS) study, we collected data on CVD risk factors [VO2–peak (mL⋅kg–1⋅min–1), body mass index (BMI, kg/m2), systolic blood pressure (SBP, mmHg), and total-cholesterol/HDL-cholesterol (Total/HDL)] among CCS aged 9–18 years. CVD risk factors were compared to references with immediate t-tests. We transformed CVD risk factors into z-scores based on international references and generated an individual CVD risk score: [inverse ZVO2–peak + ZBMI + ZSBP + ZTotal/HDL)/4]. Multivariable mixed linear regression models were used to analyze the associations between device-measured PA intensities and CVD risk factors.ResultsWe included 157 CCS aged on average 13.4 years at inclusion and 8.2 years from diagnosis. Male CCS had lower VO2–peak compared to references (45.4 vs. 49.4 mL⋅kg–1⋅min–1, P = 0.001), higher diastolic BP (67 vs. 63 mmHg, P < 0.001), lower HDL (1.35 vs. 1.44 mmol/L, P = 0.012), as well as a tendency to higher CVD risk score (z-score=0.14 vs. 0.00, P = .075). Female CCS’ CVD risk factors were comparable to references. Vigorous-intensity PA (VPA) was associated with CVD risk factors. A 10-min increase in VPA was associated with higher VO2–peak (β = 4.9, 95% CI, 2.1–7.7), lower Total/HDL (β = −0.3, 95% CI, −0.6 to −0.1) and a lower CVD risk score (β = −0.4, 95% CI, −0.6 to −0.2).ConclusionMale adolescent CCS had less favorable values of CVD risk factors compared to references. VPA in adolescent CCS is associated with clinically meaningful favorable values of CVD risk factors.

Obesity in male volcano mice Neotomodon alstoni affects the daily rhythm of metabolism and thermoregulation.

The mouse N. alstoni spontaneously develops the condition of obesity in captivity when fed regular chow. We aim to study the differences in metabolic performance and thermoregulation between adult lean and obese male mice. The experimental approach included indirect calorimetry using metabolic cages for VO2 intake and VCO2 production. In contrast, the body temperature was measured and analyzed using intraperitoneal data loggers. It was correlated with the relative presence of UCP1 protein and its gene expression from interscapular adipose tissue (iBAT). We also explored in this tissue the relative presence of Tyrosine Hydroxylase (TH) protein, the rate-limiting enzyme for catecholamine biosynthesis present in iBAT. Results indicate that obese mice show a daily rhythm persists in estimated parameters but with differences in amplitude and profile. Obese mice presented lower body temperature, and a low caloric expenditure, together with lower VO2 intake and VCO2 than lean mice. Also, obese mice present a reduced thermoregulatory response after a cold pulse. Results are correlated with a low relative presence of TH and UCP1 protein. However, qPCR analysis of Ucp1 presents an increase in gene expression in iBAT. Histology showed a reduced amount of brown adipocytes in BAT. The aforementioned indicates that the daily rhythm in aerobic metabolism, thermoregulation, and body temperature control have reduced amplitude in obese mice Neotomodon alstoni.

Aerobic capacity of professional soccer players before and after COVID-19 infection

This investigation aimed to assess the aerobic capacity of professional soccer players pre-and post-COVID-19 infection. Twenty-one division-1 elite soccer players (age 24.24 ± 5.75 years, height 178.21 ± 5.44 cm, weight 74.12 ± 5.21 kg) participated in this study. This observational study compared the same players' aerobic capacity pre-, and 60-days post COVID-19 recovery. The statistical analysis demonstrated that the infected players had significantly lower VO2max values [t(20) = 5.17, p < 0.01, d = 0.613 (medium effect)], and significantly lower VO2 values at respiratory compensation point (RC) [t(20) = 2.97, p < 0.05, d = 0.39 (small effect)] after recovery. Furthermore, results indicated a significantly lower running time (RT) on the treadmill [t(20) = 4.84, p < 0.01, d = 0.46 (small effect)] when compared to the results that were obtained before they got infected. In addition, velocity at VO2max (VVO2max) was significantly lower [t(20) = 2.34, p < 0.05, d = 0.41 (small effect)] and the heart rate values at ventilatory threshold (VT) [t(20) = −2.79, p < 0.01, d = 0.55 (medium effect)] and RC [t(20) = −3.72, p < 0.01, d = 0.52 (medium effect)] were significantly higher post-recovery. The aforementioned findings indicate that post COVID-19 soccer players may not reach full recovery at two months. Therefore, our results highlight that further adaptations and improvements are needed with regard to aerobic capacity before soccer players return to professional games.

남성 심부전 환자의 넙다리 네갈래근 근력이 최대 유산소 능력과 재입원에 미치는 영향

Purpose: The cardiopulmonary exercise test (CPET) is widely used to evaluate the clinical prognosis in patients with heart failure (HF). However, some patients with HF cannot perform CPET at maximal exercise intensity because of unstable medical condition or musculoskeletal problems. Thus, the study aimed to investigate the effects of quadriceps maximal voluntary isometric contraction (Q-MVIC) strength on aerobic capacity and re-hospitalization (RH). Methods: Patients with HF (n = 60, 59.03 ± 13.4 years, male 100%) were recruited in this study. We evaluated the Q-MVIC strength and aerobic capacity after discharge from hospitalization and followed up the RH rate during home-based self-care periods. Results: The RH (n = 15, 64.00 ± 14.69) group showed significantly lower Q-MVIC strength (p = .028) than the no RH(NRH, n = 45, 57.78 ± 13.15) group. In addition, the RH group showed significantly lower peak VO2 (p &lt; .001) than the NRH group. Moreover, the Q-MVIC strength and peak VO2 demonstrated significant correlation (r = .414, p &lt; .001). Conclusion: Our study showed that the knee extensor strength has strong predictive values on aerobic capacity and RH rate in patients with HF.

Factors Determining the Resistive Switching Behavior of Transparent InGaZnO‐Based Memristors

The overarching goal herein is to identify the factors dominating the performance of a‐IGZO‐based memristors. Despite the highest on/off ratio, greater than 104 with a preferred minimal set/reset bias achieved from a‐IGZO‐based memristors, it is observed that the switching performance and stability/reliability of the devices is significantly dominated by the VO·· density and metallization material, depending on their reactivity with IGZO. As the first governing factor, ensuring optimal VO·· concentration in the switching layer IGZO (VO··/OOx ratio 24.3% in this study) is crucial to obtain the tractable formation and rupture of conduction filament. Neither higher nor lower VO·· density than the optimized results in detrimental reliability issues, which may be ascribed to an uncontrollable filament in an abundant vacancy environment or a weak conducting path, respectively. As the second governing mechanism determining the memristor performance and reliability, it is suggested that metallization materials need to be carefully selected based on the thermodynamic redox potential and interfacial stability of the metallization material with IGZO. Metallization materials with larger reduction potential and interfacial stability are found to yield higher switching on/off ratio and greater device performance reliability.

CARDIOPULMONARY TEST PARAMETERS USEFUL FOR ADDRESSING PATIENTS WITH PECTUS EXCAVATUM TO PROMOTION OF PHYSICAL ACTIVITY

Objective: Exercise training increases muscle VO2 by increasing O2 transport and O2 uptake positively affecting cardiac output. In subjects with pectus excavatum cardiac output increase during exercise might be limited by the conformation of the chest. In this condition, the psychological impact of the deformity can further reduce the propensity to physical activity, leading to a sedentary lifestyle. Surgery is the preferred choice in severe cases. However, many patients with milder deformities can benefit from exercise-based treatment. The choice of the therapeutic strategy is fundamental, but the functional parameters on which to base this choice are not yet well defined. Therefore, we investigated the relationships between habitual physical activity and functional physiological parameters obtained from the cardiopulmonary exercise test (exercise performance and stroke volume at peak exercise) in pectus excavatum. Design and method: A cohort of adolescents (15 with pectus excavatum and 15 age- and sex-matched healthy controls) underwent Cardiopulmonary Exercise Test to estimate exercise performance (VO2 max) and stroke volume at peak exercise (VO2/HR, O2 pulse). Habitual weekly physical activity, estimated with International Physical Activity Questionnaire – Short Form (IPAQ-SF), was expressed as METs h-1·week-1. Determinants of exercise performance and stroke volume at peak exercise were investigated in the whole group with multivariable linear regression analysis adjusted for sex, body mass index, forced expiratory volume in the first second, and presence of pectus excavatum. Results: When compared to healthy controls, subjects with pectus excavatum had lower VO2 max (37.2 ± 6.6 vs 45.4 ± 6.4 mL·kg-1·min-1, p &lt; 0.05), and O2 pulse (12.1 ± 2.4 vs 16.2 ± 3.6 mL·min-1·bpm-1, p &lt; 0.05). Importantly, physical activity level was a predictor of VO2 max (B = 0.085; 95% Cl 0.010 to 0.160) while it did not affect O2 pulse (B = 0.035; 95% Cl -0.004 to 0.074). Conclusions: Training programs should be encouraged to increase cardiopulmonary performance in subjects with pectus excavatum. A marked reduction in O2 pulse at peak exercise might be considered as a criteria to address a subject towards surgery.

Real‐world estimate of the value of one metabolic equivalent in a population of patients planning major surgery

One metabolic equivalent (MET) is equal to resting oxygen consumption. The average value for one MET in humans is widely quoted as 3.5 mL/kg/min. However, this value was derived from a single male participant at the end of the 19th century and has become canonical. Several small studies have identified varied estimates of one MET from widely varying populations. The ability of a patient to complete 4 MET (or 14 mL/kg/min) is considered an indicator of their fitness to proceed to surgery. To define a typical value of one MET from a real-world patient population, as well as determine factors that influenced the value. A database of cardiopulmonary exercise testing (CPET) was interrogated to find a total of 1847 adult patients who had undergone CPET testing in the previous 10 years. From this database, estimates of oxygen consumption (VO2 ) at rest and at the anaerobic threshold and several other variables were obtained. The influence of age, body mass index (BMI), sex and the use of beta-blockers was tested. The median resting VO2 at rest was 3.6 mL/kg/min (interquartile range (IQR): 3.0-4.2). Neither sex, age >65 years or the use of beta-blockers produced a significant difference in resting VO2 , while those with a BMI >25 kg/m2 had a significantly lower VO2 at rest (3.4 mL/kg/min vs 4.0 mL/kg/min; P < 0.001). The estimate of 3.6 mL/kg/min for resting VO2 presented here is consistent with the previous literature, despite this being the first large study of its kind. This estimate can be safely used for pre-operative risk stratification.

Associations between food portion sizes, insulin resistance, VO2 max and metabolic syndrome in European adolescents: The HELENA study

Background and aimsThis study aims to examine the associations of food portion size (PS) with markers of insulin resistance (IR) and clustered of metabolic risk score in European adolescents. MethodsA total of 495 adolescents (53.5% females) from the Healthy Lifestyle in Europe by Nutrition in Adolescence (HELENA) study were included. The association between PS from food groups and homeostasis model assessment of insulin resistance (HOMA-IR) index, VO2 max, and metabolic risk score was assessed by multilinear regression analysis adjusting for several confounders. Analysis of covariance (ANCOVA) was used to determine the mean differences of food PS from food groups by HOMA-IR cutoff categories by using maternal education as a covariable. ResultsLarger PS from vegetables in both gender and milk, yoghurt, and milk beverages in males were associated with higher VO2 max, while larger PS from margarines and vegetable oils were associated with lower VO2 max (p < 0.05). Males who consumed larger PS from fish and fish products; meat substitutes, nuts, and pulses; cakes, pies, and biscuits; and sugar, honey, jams, and chocolate have a higher metabolic risk score (p < 0.05). Males with lower HOMA-IR cutoff values consumed larger PS from vegetables, milk, yoghurt, and milk beverages (p < 0.05). Females with lower HOMA-IR cutoff values consumed larger PS from breakfast cereals, while those with higher HOMA-IR cutoff values consumed larger PS from butter and animal fats (p = 0.018). ConclusionThe results show that larger PS from dairy products, cereals, and high energy dense foods are a significant determinant of IR and VO2 max, and larger PS from food with higher content of sugar were associated with higher metabolic risk score.

P295 EXERCISE OXYGEN KINETIC IN HYPERTROPHIC CARDIOMYOPATHY: RESULTS FROM A MULTICENTER CARDIOPULMONARY EXERCISE TESTING STUDY

Abstract Aims Reduced cardiac output (CO) has been considered crucial in symptoms’ genesis in hypertrophic cardiomyopathy (HCM). We evaluated the cardiopulmonary exercise testing (CPET) response in HCM focusing on parameters strongly associated with stroke volume (SV) and cardiac output (CO), such as oxygen uptake (VO2) and O2–pulse, considering both their absolute values and temporal behavior during physical exercise. Methods and Results We enrolled 312 non–end stage HCM patients, divided according to left ventricle outflow tract obstruction (LVOTO) at rest or during Valsalva maneuver (72% with LVOTO&amp;lt;30; 10% between 30 and 49 and 18% ≥ 50mmHg). Peak VO2 (percent of predicted), O2–pulse and ventilation to carbon dioxide production (VE/VCO2) slope did not change across LVOTO groups. Ninety–six (31%) HCM patients presented an abnormal O2–pulse temporal behavior, irrespective of LVOTO values. These patients showed lower peak systolic pressure, workload (106±45 vs. 130±49W), VO2 (74±17 vs. 80±20%) and O2–pulse (12 [9–14] vs. 14 [11–17]ml/beat), with higher VE/VCO2 slope (28 [25–31] vs. 27 [24–31]) (p &amp;lt; 0.005 for all). Only 2 patients had an abnormal VO2/work slope. Conclusion None of CPET parameters, either as absolute values or dynamic relationships, were associated with LVOTO. Differently, an abnormal O2–pulse exercise behavior, which is strongly related to inadequate SV during exercise, correlates with reduced functional capacity (peak and anaerobic threshold VO2 and workload) and increased VE/VCO2 slope, helping identifying more advanced disease irrespectively of LVOTO. Adding O2–pulse kinetics evaluation to standard CPET could lead to a potential incremental benefit in terms of HCM prognostic stratification and, then, therapeutic management.

Association of sarcopenia and oxygen uptake efficiency slope in male patients with heart failure: The skeletal muscle hypothesis in practice

Abstract Funding Acknowledgements Type of funding sources: Foundation. Main funding source(s): Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Background Sarcopenia, a generalized loss of muscle mass and function, is a common comorbidity in patients with heart failure (HF). The skeletal muscle, through afferent nerve pathways, modulates the respiratory response during physical efforts. However, whether ventilatory behavior is affected by the presence of sarcopenia is still unknown. Purpose To evaluate the impact of sarcopenia in ventilatory parameters of patients with HF. Methods We enrolled 169 male patients with stable chronic HF with left ventricular ejection fraction &amp;lt;40% (LVEF). Muscle strength was measured by handgrip dynamometer. Body composition was measured with dual-energy X-ray absorptiometry (DXA). Appendicular skeletal muscle (ASM) was comprised by lean muscle mass of both arms and legs. Sarcopenia was defined by handgrip strength and ASM/height2 lower than 27 kg and 7.0 kg/m2, respectively. Ventilation (VE), oxygen consumption (VO2), and carbon dioxide output (VCO2) were evaluated using breath-by-breath measurements during a cardiopulmonary exercise test performed on a cycle ergometer. Oxygen uptake efficiency slope (OUES) was calculated from data taken at exercise peak. Results Sarcopenia was identified in 29 patients (17.2%). Patients with sarcopenia had lower body mass index (BMI; 21.2±2.4 vs. 26.5±3.8 kg/m2, p&amp;lt;0.0001) with higher C-reactive protein [CRP; 12.4 (2.8-22.4) vs. 2.4 (1.0-6.3) mg/L, p&amp;lt;0.001] and brain natriuretic peptide [BNP; 949 (446-1722) vs. 374 (127-885) pg/mL, p&amp;lt;0.001] compared to patients without sarcopenia, respectively. At the first ventilatory threshold, VE/VO2 (36.9±5.9 vs. 32.7±6.5, p=0.003) and VE/VCO2 (39.8±7.2 vs. 35.3±6.9, p=0.004) were higher in sarcopenic patients compared to those without sarcopenia. At the exercise peak, comparing to patients without sarcopenia, sarcopenic patients had lower OUES (1,186±295 vs. 1,634±564, p&amp;lt;0.001), absolute VO2 (0.93±0.25 vs. 1.43±0.47 L/min, p&amp;lt;0.0001), relative VO2 (16.2±5.0 vs. 19.5±6.5 ml/kg/min, p=0.011), and VE (47.3±10.1 vs. 63.0±18.2 L/min, p&amp;lt;0.001), while VE/VCO2 (42.9±8.9 vs. 38.7±8.4, p=0.025) was increased and VE/VO2 (49.6±11.5 vs. 45.1±10.8, p=0.066) showed a tendency to be higher. OUES was positively correlated with total lean body mass (r=0.38; p&amp;lt;0.0001), ASM/height2 (r=0.36; p&amp;lt;0.0001), and handgrip strength (r=0.31; p&amp;lt;0.001). In a multivariate logistic regression model using OUES as the dependent variable, ASM/height2 (OR, 1.466; 95% CI, 1.003–2.141; p=0.048), haemoglobin (OR, 0.346; 95% CI, 0.135–0.886; p=0.027), and creatinine (OR, 0.391; 95% CI, 0.166–0.918; p=0.031) were independently associated with OUES adjusted by age, BMI, LVEF, BNP, CRP, and beta-blocker use. Conclusion Our results suggest that sarcopenia, possibly by reducing thoracic skeletal muscle mass or inefficiently modulating ventilation through afferent pathways, is related to impaired ventilatory response during exercise in patients with HF.

Exercise Oscillatory Ventilation in Hypertrophic Cardiomyopathy.

To assess the prevalence and clinical correlates of exercise oscillatory ventilation (EOV) in patients with hypertrophic cardiomyopathy (HCM). Retrospective single-center study. Thirty-six consecutive HCM patients who underwent cardiopulmonary exercise testing. Two patients (5.6%) had EOV. Both patients with peak oxygen consumption (VO2) less than or equal to 9.1 ml/kg/min had EOV. Left atrial size was greater in patients with EOV. Of the 2 patients in the study population with an abnormal blood pressure response to exercise, 1 had EOV. Both patients with New York Heart Association Class 3 heart failure had EOV. This is the first report of EOV in HCM. EOV is uncommon in patients with HCM. EOV appears to be a marker of disease severity as evidenced by overt heart failure, left atrial enlargement, and low peak VO2.

Impact of moderately reduced renal function on the diagnostic and prognostic value of galectin-3 in patients with exertional dyspnea.

Blood concentration of galectin-3 (Gal-3) - a biomarker of fibrosis useful in diagnostics and prognostication in heart failure (HF) - is known to be elevated in patients with renal impairment, a condition which often accompanies cardiac insufficiency. To investigate the effect of moderately reduced renal function (estimated glomerular filtration rate (eGFR) 30-60 mL/min/1.73 m2) on the diagnostic and prognostic utility of circulating Gal-3 in patients with HF with preserved ejection fraction (HFpEF). Clinical, biochemical and echocardiographic variables were collected at baseline in 154 patients with HFpEF: 101 with normal and 53 with moderately reduced renal function, who were followed up for 48 (24-60) months for HF hospitalization and cardiovascular (CV) death (composite endpoint). Patients with moderately impaired renal function were characterized by higher age, Meta-Analysis Global Group in Chronic Heart Failure (MAGGIC) risk score, Gal-3, B-type natriuretic peptide (BNP) and New York Heart Association (NYHA) class, lower hemoglobin, and more advanced left ventricular diastolic dysfunction. Older age, female sex and deeper impairment of renal performance were determinants of higher Gal-3 blood concentrations. Lower exercise capacity (lower peak VO2) was associated with higher Gal-3 level and more pronounced renal impairment. Multivariable regression analysis demonstrated the significance of renal dysfunction as a determinant of lower exercise capacity and revealed a significant interaction between Gal-3 and eGFR with respect to peak VO2. The addition of Gal-3 to the prognostic models based on clinical data improved their predictive power for the study endpoint. The Kaplan-Meier analysis revealed that the presence of moderately reduced renal function with eGFR 30-60 mL/min/1.73 m2 did not enhance the increased risk of adverse outcome associated with Gal-3 above the median. In patients with HFpEF, the coexistence of moderate renal dysfunction does not deteriorate the prognostic usefulness of circulating Gal-3. However, renal impairment modifies the association between Gal-3 and exercise capacity, which supports the need to adjust for kidney function when interpreting the contribution of Gal-3 to exercise intolerance in this population.

The Performance, Physiology and Morphology of Female and Male Olympic-Distance Triathletes.

Sex differences in triathlon performance have been decreasing in recent decades and little information is available to explain it. Thirty-nine male and eighteen female amateur triathletes were evaluated for fat mass, lean mass, maximal oxygen uptake (VO2 max), ventilatory threshold (VT), respiratory compensation point (RCP), and performance in a national Olympic triathlon race. Female athletes presented higher fat mass (p = 0.02, d = 0.84, power = 0.78) and lower lean mass (p < 0.01, d = 3.11, power = 0.99). VO2 max (p < 0.01, d = 1.46, power = 0.99), maximal aerobic velocity (MAV) (p < 0.01, d = 2.05, power = 0.99), velocities in VT (p < 0.01, d = 1.26, power = 0.97), and RCP (p < 0.01, d = 1.53, power = 0.99) were significantly worse in the female group. VT (%VO2 max) (p = 0.012, d = 0.73, power = 0.58) and RCP (%VO2 max) (p = 0.005, d = 0.85, power = 0.89) were higher in the female group. Female athletes presented lower VO2 max value, lower lean mass, and higher fat mass. However, females presented higher values of aerobic endurance (%VO2 max), which can attenuate sex differences in triathlon performance. Coaches and athletes should consider that female athletes can maintain a higher percentage of MAV values than males during the running split to prescribe individual training.

Comparison of the Beacon and Quark indirect calorimetry devices to measure resting energy expenditure in ventilated ICU patients

Critically ill patients in the Intensive Care Unit (ICU) should receive nutritional support matched to their metabolic needs as both under- and overfeeding energy has been shown to increase mortality. Critical illness can significantly affect metabolism. Consequently, resting energy expenditure (REE) can vary markedly during critical illness. Therefore, indirect calorimetry to estimate REE is recommended to determine energy requirements in individual ICU patients and to guide optimal nutritional support. Currently, the Quark metabolic monitor is considered the gold standard in our ICU, but novel mechanical support devices are also equipped with indirect calorimetry functionalities. This study aimed to evaluate the performance of a currently unevaluated device. A cross-sectional analysis in mechanically ventilated patients was conducted in a mixed medical-surgical ICU. The primary outcome was a numerical and visual comparison of the performance of the Beacon indirect calorimeter to calculate REE compared to the Quark device using Bland Altman plots. Performance was evaluated using bias, precision, accuracy, and reliability. Secondary analysis included a comparison with REE estimated by predictive equations. Seventy-one measurements were obtained in 27 mechanically ventilated subjects. An underestimation by the Beacon device in calculated REE of-96.2kcal/day (4.5%) was found. There was a bias towards higher VCO2 and lower VO2 values with Beacon as compared to Quark. The reliability of the Beacon was good, with an absolute intraclass correlation coefficient of 0.897 (95%CI 0.751-0.955; p=0.000). There was a poor correlation (<0.40) between the separate indirect calorimetry devices and most predictive equations. Only the Faisy predictive equations had good reliability (ICC 0.687, p=0.002). Beacon indirect calorimetry accurately determined REE in mechanically ventilated critically ill patients compared to the gold standard in our ICU (Quark indirect calorimeter), although confidence intervals were wide. There was low bias and good reliability. On the other hand, predictive equations performed poorly compared to both devices, underestimating the true metabolic needs of mechanically ventilated ICU patients.

Anisocytosis is associated with myocardial fibrosis and exercise capacity in heart failure with preserved ejection fraction

BackgroundRed Blood Cell Distribution Width (RDW), a measure of variability in size of circulating red blood cells and is a marker of inflammation. ObjectivesWe sought to test the hypothesis that RDW reflects an inflammatory milieu permissive for cardiac fibrosis in those with Heart Failure and preserved ejection fraction (HFpEF). MethodsWe analyzed the association between RDW and fibrosis in two separate cohorts. Cohort 1 (n = 200) was a retrospective analysis of blood biomarkers measured in the RELAX trial (Clinicaltrials.gov NCT00763867) and Cohort 2 (n = 160) included a single center cohort of patients with preserved ventricular function referred for cardiac magnetic resonance imaging (cMRI). Linear regression was used to adjust for potential confounders, and a mediation analysis used to explore relationships with exercise intolerance (peak VO2 max). ResultsWithin Cohort 1, anisocytosis (RDW > 14.5) was prevalent (49.5%) and was associated with greater baseline clinical comorbidities, a lower Peak VO2 and more frequent heart failure hospitalizations. The RDW was associated with biomarkers of inflammation and cardiac fibrosis. In Cohort 2, RDW was associated with cMRI myocardial fibrosis (extracellular volume; Spearman's rho=0.38, P<0.001) which was independent of age, sex, LV ejection fraction, and hematocrit (P = 0.026). Individuals with both anisocytosis and myocardial fibrosis identified a subgroup of at high risk for 2-year mortality (HR 16.28 [4.30–61.66], P<0.001). ConclusionsIn two independent cohorts of patients with HFpEF, elevated RDW is associated reduced exercise capacity and greater fibrosis as measured by serum biomarkers and cMRI. Additional studies are needed to validate this novel relationship.

The VIP/VPAC1R Pathway Regulates Energy and Glucose Homeostasis by Modulating GLP-1, Glucagon, Leptin and PYY Levels in Mice.

Simple SummaryThe current study is the first complete characterization of the phenotypic, metabolic, calorimetric, and homeostatic effects of VPAC1R in a null murine model. To evaluate the role of VPAC1R on body phenotype, feeding behavior, glucose/energy homeostasis, metabolic rate and plasma hormones, a long-term study was conducted in VPAC1R−/− and WT mice. The outcome data document that VPAC1R−/− mice have altered metabolism and insulin intolerance, with significant increase of feeding bouts, reduction of total energy expenditure and respiratory gases during both the dark and light cycle, together with elevated fasting levels of GLP-1 and PYY, and higher postprandial levels of GLP-1, glucagon leptin and PYY. These findings suggests that VPAC1R controls glucose homeostasis and energy balance by regulating plasma metabolic hormones.Vasoactive Intestinal Peptide binds with high affinity to VPAC1R and VPAC2R, thus regulating key physiologic functions. Previously, we documented in VIP−/− mice a leaner body phenotype and altered metabolic hormones. Past reports described in VPAC2−/− mice impaired circadian rhythm, reduced food intake, and altered metabolism. To better define the effects of VPAC1R on body phenotype, energy/glucose homeostasis, and metabolism, we conducted a 12-week study in a VPAC1R null model. Our results reveal that VPAC1−/− mice experienced significant metabolic alterations during the dark cycle with greater numbers of feeding bouts (p = 0.009), lower Total Energy Expenditure (p = 0.025), VO2 (p = 0.029), and VCO2 (p = 0.016); as well as during the light cycle with lower Total Energy Expenditure (p = 0.04), VO2 (p = 0.044), and VCO2 (p = 0.029). Furthermore, VPAC1−/− mice had significantly higher levels of GLP-1 and PYY during fasting, and higher levels of GLP-1, glucagon leptin and PYY during postprandial conditions. In addition, VPAC1−/− mice had lower levels of glucose at 60′ and 120′, as assessed by insulin tolerance test. In conclusion, this study supports a key role for VPAC1R in the regulation of body glucose/energy homeostasis and metabolism.

Physiological Responses to Acute Cycling With Blood Flow Restriction.

Aerobic exercise with blood flow restriction (BFR) can improve muscular function and aerobic capacity. However, the extent to which cuff pressure influences acute physiological responses to aerobic exercise with BFR is not well documented. We compared blood flow, tissue oxygenation, and neuromuscular responses to acute cycling with and without BFR. Ten participants completed four intermittent cycling (6 × 2 min) conditions: low-load cycling (LL), low-load cycling with BFR at 60% of limb occlusion pressure (BFR60), low-load cycling with BFR at 80% of limb occlusion pressure (BFR80), and high-load cycling (HL). Tissue oxygenation, cardiorespiratory, metabolic, and perceptual responses were assessed during cycling and blood flow was measured during recovery periods. Pre- to post-exercise changes in knee extensor function were also assessed. BFR60 and BFR80 reduced blood flow (~33 and ~ 50%, respectively) and tissue saturation index (~5 and ~15%, respectively) when compared to LL (all p < 0.05). BFR60 resulted in lower VO2, heart rate, ventilation, and perceived exertion compared to HL (all p < 0.05), whereas BFR80 resulted in similar heart rates and exertion to HL (both p > 0.05). BFR60 and BFR80 elicited greater pain compared to LL and HL (all p < 0.05). After exercise, knee extensor torque decreased by ~18 and 40% for BFR60 and BFR80, respectively (both p < 0.05), and was compromised mostly through peripheral mechanisms. Cycling with BFR increased metabolic stress, decreased blood flow, and impaired neuromuscular function. However, only BFR60 did so without causing very severe pain (>8 on pain intensity scale). Cycling with BFR at moderate pressure may serve as a potential alternative to traditional high-intensity aerobic exercise.

Oxygen Uptake in Repeated Cycling Sprints Against Different Loads Is Comparable Between Men and Preadolescent Boys.

Children recover faster than adults in repeated sprints, but it is unclear if their aerobic responses differ.PurposeThis study tested the hypothesis that aerobic response (VO2) during repeated sprints is greater in preadolescent boys than in men. Further, this study compared normalization with conventional ratio-scaling and scaling with the use of body mass (BM) as a covariate.MethodsNine boys (age: 11.8 ± 0.6 years, swimmers) and 11 men (age: 21.7 ± 0.6 years, recreational athletes) performed 10 maximal 6-s cycling sprints separated by 24-s of passive recovery, against two loads (optimum and 50% of optimum). Oxygen uptake (VO2) was measured continuously.ResultsMen’s mean power output (MPO) was greater than boys in each sprint, both in absolute (unscaled) values ( p < 0.05) and when adjusted for lean leg volume ( p < 0.05). Children had lower absolute VO2 ( p < 0.05) than men, but when it was adjusted for BM or power-output, VO2 was comparable between men and boys. Thus, most of the difference in VO2 between men and boys was due to body size and power-output differences.ConclusionOur results suggest that men and boys have similar VO2 during repeated sprints when appropriately adjusted to body mass or power output. Results highlight the importance of using appropriate scaling methods to compare adults’ and children’s aerobic responses to high-intensity exercise.

Exercise oxygen pulse kinetics in patients with hypertrophic cardiomyopathy

ObjectivesReduced cardiac output (CO) has been considered crucial in symptoms’ genesis in hypertrophic cardiomyopathy (HCM). Absolute value and temporal behaviour of O2-pulse (oxygen uptake/heart rate (VO2/HR)), and the VO2/work relationship...

Tertiary amino-modified GO/Nafion composite membrane with enhanced ion selectivity for vanadium redox flow batteries

Tertiary amino-modified graphene oxide (GO) nanosheet (named as TAGO) was successfully synthesized by gamma-ray radiation-induced grafting of dimethylaminoethyl methacrylate onto the surface of GO. Then, a novel Nafion-TAGO composite membrane was prepared by solution casting method and TAGO could be dispersed uniformly in the Nafion due to a good compatibility with the Nafion matrix. In the composite membrane, acid-base pairs were formed through hydrogen-bond network among the tertiary amino groups, the carboxylic acid groups and hydroxyl groups in TAGO and/or sulfonic acid groups in Nafion, respectively. Owing to the acid-base pair interactions (such as –SO3H … -N(CH3)2), the ionic channels for proton transport could be provided in the composite membrane. As a result, the Nafion-TAGO composite membrane exhibited excellent thermal stability, high proton conductivity, low VO2+ permeability and high ion selectivity. Therefore, the TAGO is a good candidate for the performance improvement of Nafion used in vanadium redox flow battery.