Total VO2 Research Articles

Direct electron transfer double-defect core–shell LaVCuOδ@CeOx nanoreactors boosting hydrogen peroxide activation for enhanced quinoline removal

Double oxygen vacancies (VO) tuned core–shell LaVCuOδ@CeOx (VO-LCO@CeOx) nanoreactors with direct electron transfer (DET) structure was synthesized as an effective heterogeneous Fenton-like catalyst for the quinoline removal. The DET structure was constructed by electron-rich ≡Cu center of VO-LCO core and electron-capture center of CeOx shell for electrons supplying and consuming. This structure elevated total VO levels of catalyst through the removal of oxygen atoms in CeO2 from attice to interface sites. Meanwhile, the ≡Ce(III) acted as reactive sites for the adsorption of hydrogen peroxide (H2O2) to form surface peroxide species, and then the electron-rich ≡Cu center was further provided electrons to surface peroxide species by DET to produce hydroxyl radical. Moreover, the newly formed surface VO would also be further promote hydroxyl radical production through self-activation of H2O2. This catalyst displayed excellent catalytic activity and stability. The density functional theory (DFT) results further pointed out that this structure had excellent adsorption energy, and generable electron transfer from VO-LCO to CeOx. This work provided a novel approach for the development of heterogeneous Fenton-like catalysts to degrade quinoline wastewater.

Suppression of Strain Relaxation in VO2/TiO2 Multilayered Films

Strained VO2 films grown on (001) rutile TiO2 exhibit an abrupt insulator-to-metal transition (IMT) around room temperature. The transition temperature (Tc) increases when the critical thickness of ∼15 nm is exceeded. The strain relaxation is responsible for crack formation. Here, we show that inserting thin TiO2 layers suppresses the strain relaxation of VO2. We fabricated several VO2/TiO2/VO2 trilayer films on (001) TiO2 substrates. Each film had a VO2 film of 8 nm, but the TiO2 thickness was varied. Strained VO2/TiO2 multilayer films show IMT with clear hysteresis around room temperature when the TiO2 thickness exceeds 4 nm. In addition, we fabricated 8 nm thick VO2/9 nm thick TiO2 multilayered films. Tc is maintained around room temperature even though the total VO2 thickness is ∼50 nm. The present results provide a useful design concept of thin-film materials for thermochromic applications of strained VO2.

High-Intensity Interval Training for Rowing: Acute Responses in National-Level Adolescent Males.

Background: This study investigated the acute effects of two high-intensity interval training (HIIT) programs on physiological responses and internal workload. Methods: Ten national-level adolescent male rowers (age: 15.7 ± 0.2 years; maximal oxygen uptake (VO2max): 60.11 ± 1.91 mL∙kg−1∙min−1) performed two HIIT testing sessions: short (S-HIIT) and long (L-HIIT). In S-HIIT, the rowers performed 25 reps of 30 s at 100% power at VO2max (Pmax) interspersed with 30 s at P@20% Pmax; whereas in L-HIIT, the rowers executed 4 × 4 min at P@90% Pmax interspersed with 3 min of active recovery (P@30% Pmax). Results: The acute physiological responses and internal workload were evaluated. The significance level was set at p < 0.05. Oxygen uptake (VO2) (p < 0.05), time spent per session at ~90% VO2max (p < 0.01), total VO2 consumed (p < 0.01), total distance (p < 0.001), the rating of perceived exertion, blood lactate concentration and heart rate (always p < 0.0001) were significantly higher in L-HIIT than in S-HIIT. However, peak power output was significantly lower in L-HIIT compared to S-HIIT (p < 0.0001). Conclusion: In adolescent rowers, both HIIT tests stimulated aerobic and anaerobic systems. The L-HIIT test was associated with acute cardiorespiratory and metabolic responses, as well as higher perceptions of effort than the S-HIIT test. In adolescent rowers, HIIT emerges as an asset and could be introduced into a traditional in-season, moderate-intensity and endurance-based rowing program once a week.

Pulmonary 99mTc-HMDP uptake correlates with restrictive ventilatory defects and abnormal lung reactance in transthyretin cardiac amyloidosis patients

BackgroundPulmonary involvement in individuals with transthyretin cardiac amyloidosis is unclear. The aim of this study was to quantify 99mTc-hydroxy methylene diphosphonate (HMDP) lung retention in hereditary transthyretin (ATTRv) cardiac amyloidosis patients and to relate tracer uptake intensity to pulmonary function and aerobic capacity.MethodsWe prospectively enrolled 20 patients with biopsy-proven ATTRv cardiac amyloidosis and 20 control subjects. Cardiac involvement was confirmed by echocardiography and nuclear imaging using 99mTc-HMDP. Semi-quantitative analysis of the heart, rib and lung retention was assessed using a simple region of interest technique. Pulmonary function was evaluation by the means of whole-body plethysmography, diffusing capacity of the lung for carbon monoxide, forced oscillation technique and cardiopulmonary exercise testing.ResultsPulmonary tracer uptake estimated by lung to rib retention ratio was higher in ATTRv amyloidosis patients compared with control subjects: median 0.62 (0.55–0.69) vs 0.51 (0.46–0.60); p = 0.014. Analysis of relation between lung 99mTc-HMDP retention and pulmonary function parameters shown statistically significant correlations with total lung volume (% predicted), lung reactance (Xrs 5 Hz) and peak VO2, suggesting total lung capacity restriction impaired elastic properties of the lung and poor aerobic capacity.ConclusionOur study suggests that some grade of pulmonary retention of 99mTc-HMDP may occur in patients with cardiac ATTRv amyloidosis, which can elicit deleterious effects on patient’s lung function and aerobic capacity.

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.

Effects of the exercise training on skeletal muscle oxygen consumption in heart failure patients with reduced ejection fraction

AimsSkeletal muscle dysfunction is a systemic consequence of heart failure (HF) that correlates with functional capacity. However, the impairment within the skeletal muscle is not well established. We investigated the effect of exercise training on peripheral muscular performance and oxygenation in HF patients. Methods and resultsHF patients with ejection fraction ≤40% were randomized 2:1 to exercise training or control for 12 weeks. Muscle tissue oxygen was measured noninvasively by near-infrared spectroscopy (NIRS) during rest and a symptom-limited cardiopulmonary exercise test (CPET) before and after intervention. Measurements included skeletal muscle oxygenated hemoglobin concentration, deoxygenated hemoglobin concentration, total hemoglobin concentration, VO2 peak, VE/VCO2 slope, and heart rate. Muscle sympathetic nerve activity by microneurography, and muscle blood flow by plethysmography were also assessed at rest pre and post 12 weeks. Twenty-four participants (47.5 ± 7.4 years, 58% men, 75% no ischemic) were allocated to exercise training (ET, n = 16) or control (CG, n = 8). At baseline, no differences between groups were found. Exercise improved VO2 peak, slope VE/VCO2, and heart rate. After the intervention, significant improvements at rest were seen in the ET group in muscle sympathetic nerve activity and muscle blood flow. Concomitantly, a significant decreased in Oxy-Hb (from 29.4 ± 20.4 to 15.7 ± 9.0 μmol, p = 0.01), Deoxi-Hb (from 16.3 ± 8.2 to 12.2 ± 6.0 μmol, p = 0.003) and HbT (from 45.7 ± 27.6 to 27.7 ± 13.4 μmol, p = 0.008) was detected at peak exercise after training. No changes were observed in the control group. ConclusionExercise training improves skeletal muscle function and functional capacity in HF patients with reduced ejection fraction. This improvement was associated with increased oxygenation of the peripheral muscles, increased muscle blood flow, and decreased sympathetic nerve activity.

Knee Extensor Power Predicts Six-Minute Walk Test Performance In Transfemoral Amputees

PURPOSE: To quantify the relationship between intact limb quadriceps strength in transfemoral amputees and six-minute walk test (6MWT) performance. METHODS: 11 participants with unilateral transfemoral amputations (4F/7M, 46.21 ± 12.68 years old, 28.24 ± 20.57 years following amputation) completed isokinetic (120 degrees/s) and isometric quadriceps strength testing on the intact limb and the 6MWT on a treadmill with a flowmeter to measure oxygen uptake (VO2). Bivariate Pearson correlations were calculated to identify the relationship between strength and 6MWT performance. Strength measures included mass-normalized peak torque, average torque, and average power. Walking measures included total distance traveled during the 6MWT, average VO2, and total VO2. VO2 measures were normalized to distance traveled and mass. Significant correlations (P < .05) were retained for a multiple regression analysis to identify the proportion of variance explained by the distance traveled (model 1) and the total VO2 (model 2). RESULTS: Peak isokinetic knee extensor torque was correlated with total VO2 (r = -.60, P = .05) and distance traveled (r = .84, P = .001). Average isokinetic knee extensor torque was correlated with total VO2 (r = -.61, P = .046) and distance traveled (r = .85, P = .001). Average knee extensor power was correlated with total VO2 (r = -.67, P = .026) and distance traveled (r = .88, P < 0.001). Peak isometric knee extensor torque was correlated with distance traveled (r = .69, P = .019). Average knee extensor power had the strongest correlation with both distance and total VO2 and was significantly correlated with all other strength variables, therefore was the only variable entered into the linear regression models. Average power explained 77.2% of the variance in distance traveled during the 6MWT (P < .001). In the second model, average power explained 44.2% of the variance in total VO2 during the 6MWT (P = .026). CONCLUSIONS: Knee extensor strength was correlated with performance on the 6MWT in individuals with unilateral transfemoral amputation. The strongest relationship was between quadriceps power and distance traveled, which suggests that developing quadriceps power in the intact limb following amputation may be an important factor to reduce metabolic cost of walking and support a return to an active lifestyle.

Knee extensor power predicts six-minute walk test performance in people with transfemoral amputations.

Lower-limb amputees have increased metabolic costs during walking that may be mitigated by maintaining quadriceps strength and power following amputation. However, there are no current studies investigating the relationship between thigh strength and walking performance in individuals with transfemoral amputation. To quantify the relationship between intact limb quadriceps strength in transfemoral amputees and six-minute walk test (6MWT) performance. Descriptive laboratory study. Laboratory. Eleven participants with unilateral transfemoral amputations from trauma or osteosarcoma (4 women/7 men, 46.21 ± 12.68 years old, 28.24 ± 20.57 years following amputation). Strength and power testing on the intact limb followed by 6MWT with a flowmeter to measure oxygen uptake (VO2 ). Strength included mass-normalized peak torque, average torque, and average power. 6MWT measures included total distance traveled and VO2 normalized to distance and mass. Significant correlations (P ≤ .05) were retained for a regression analysis. Peak isokinetic knee extensor torque was correlated with total VO2 (r = -.60, P = .05) and distance traveled (r = .84, P = .001). Average isokinetic knee extensor torque was correlated with total VO2 (r = -.61, P = .046) and distance traveled (r = .85, P = .001). Average knee extensor power was correlated with total VO2 (r = -.67, P = .026) and distance traveled (r = .88, P < .001). Peak isometric knee extensor torque was correlated with distance traveled (r = .69, P = .019). Average power explained 77.2% of the variance in distance traveled during the 6MWT (P < .001) and average power explained 44.2% of the variance in total VO2 during the 6MWT (P = .026). Knee extensor strength was correlated with performance on the 6MWT in individuals with unilateral transfemoral amputation. The strongest relationship was between isokinetic quadriceps power and distance traveled, which suggests that developing quadriceps power in the intact limb following amputation may be an important factor to reduce metabolic cost of walking and support a return to an active lifestyle.

A role for cardiopulmonary exercise testing in detecting physiological changes underlying health status in Idiopathic pulmonary fibrosis: a feasibility study

IntroductionThere is limited data available on the use of CPET as a predictive tool for disease outcomes in the setting of IPF. We investigated the feasibility of undertaking CPET and the relationship between CPET and quality of life measurements in a well-defined population of mild and moderate IPF patients.MethodsA prospective, single-centre observational study.ResultsThirty-two IPF patients (mild n = 23, moderate n = 9) participated in the study, n = 13 mild patients attended for repeat CPET testing at 12 months. At baseline, total K-BILD scores and total IPF-PROM scores significantly correlated with 6MWT distance, but not with baseline FVC % predicted, TLco % predicted, baseline or minimum SpO2. VO2 peak/kg at AT positively correlated with total scores, breathlessness/activity and chest domains of the K-BILD questionnaire (p < 0.05). VO2 peak significantly correlated with total IPF PROM scores and wellbeing domains (p < 0.05), with a trend towards statistical significance for total IPF-PROM and VO2 peak/kg at anaerobic threshold (p = 0.06).There was a statistically significant reduction in FVC% predicted at 12 months follow up, although the mean absolute decline was < 10% (p < 0.05). During this period VO2 peak significantly reduced (21.6 ml/kg/min ± 2.9 vs 19.1 ± 2.8; p = 0.017), with corresponding reductions in total K-BILD and breathlessness/activity domains that exceeded the MCID for responsiveness. Lower baseline VO2 peak/kg at anaerobic threshold correlated with greater declines in total K-BILD scores (r = − 0.62, 0.024) at 12 months. Whilst baseline FVC% predicted or TLco % predicted did not predict change in health status,ConclusionWe have shown that it is feasible to undertake CPET in patients with mild to moderate IPF.CPET measures of VO2 peak correlated with both baseline and change in K-BILD measurements at 1 year, despite relatively stable standard lung function (declines of < 10% in FVC), suggesting its potential sensitivity to detect physiological changes underlying health status.

High-intensity Interval Exercise While Wearing A Sauna Suit Increases Energy Expenditure

PURPOSE: The use of sauna suits (SS) has increased and claims to enhance weight loss and body temperature during exercise. Whether high-intensity interval exercise (HIIE) with a SS enhances energy expenditure (EE) and excess post-exercise oxygen consumption (EPOC) is unknown. The purpose of this study was to examine changes in EE and EPOC in response to HIIE while wearing a SS. METHODS: Seven recreationally active men and women (mean age, mass, and VO2max = 29.7 ± 6.9 yr, 68.8 ± 17.3 kg, and 46.2 ± 8.10 mL/kg/min, respectively) initially completed assessment of resting metabolic rate (RMR) and maximal oxygen uptake (VO2max). During the VO2max test, exercise began at 60 W for two minutes and work rate increased 25 - 30 W/min until volitional fatigue. Heart rate (HR) and breath-by-breath gas exchange were continuously measured. At least 48 hr later, subjects completed HIIE consisting of 10 x 1 min intervals at 85% peak power output, followed by 75 s of active recovery, with or without a SS. During exercise, HR, core temperature (Tc), and gas exchange data were continuously measured, and thermal sensation and rating of perceived exertion (RPE) were also recorded. For 1 hr post-exercise, subjects rested while changes in EPOC, Tc, and HR were determined. Blood lactate concentration was measured pre-exercise, 5 min post-exercise, and 1 hr post-exercise. Subjects returned 1 wk later and completed the other condition whose order was randomized RESULTS: Compared to no SS (NSS), total VO2 (57.3 ± 13.8 L vs. 60.4 ± 13.5 L, p = 0.028) and EE (286.8 ± 69.2 kcal vs. 302.0 ± 67.3 kcal, p = 0.048) were significantly higher for SS. However, EPOC was not significantly different 1 hr post-exercise between NSS (5.1 L ± 4.3 L) and SS (7.5 L ± 5.1, p = 0.16). End-exercise HR was not different between conditions (p = 0.42), but Tc was significantly higher (p = 0.046) for SS (38.6 ± 0.5 °C) compared to NSS (38.4 ± 0.4 °C). Post-exercise blood lactate concentration was not significantly different (p = 0.20) between conditions (9.6 ± 3.5 vs. 10.8 ± 3.4 in NSS vs. SS). End-exercise thermal sensation (p = 0.60) and RPE (p = 0.17) were not significantly different between conditions. CONCLUSIONS: Wearing a SS during HIIE elicits greater EE and Tc versus not wearing a SS. Therefore, a SS may aid in weight loss by increasing the total amount of calories expended during HIIE.

Non-metabolic VCO 2, Recovery Off-kinetics, And Performance Fatigability Following Chronic Exercise

PURPOSE: This study characterized the role of non-metabolic expired carbon dioxide (nm-VCO2) in the relationship between recovery and performance fatigability (PF). METHODS: Twenty adults (men, n=9, age=44.7±13.9 years; women, n=11, age=50.3±11.1 years) completed peak cardiopulmonary exercise tests (CPET) and submaximal constant work rate tests (CWRT) on the cycle ergometer on separate days before and after a vigorous, 4-week aerobic exercise training (AET) regimen. Each test was followed by a 10-minute passive recovery and endurance test at 70% of peak watts attained during CPET. PF was indexed by endurance test duration following both peak CPET (End1) and CWRT (End2), peak CPET time (pk-Time) and watts (pk-Watts). Metabolic indices were total VCO2 (tVCO2), metabolic VCO2 (m-VCO2), nm-VCO2, and recovery VO2 and VCO2 off-kinetics response indices (ORI). Data were analyzed using paired t-tests and correlations and compared before and after AET. RESULTS: Significant improvements in recovery and PF measures were observed after AET, along with significant increases in tVCO2 and nm-VCO2. No significant change in m-VCO2 was observed.Relationships between measures of recovery and PF were observed, though the strength of the relationships were diminished (pk-Time, pk-Watts) or became non-significant (End1, End2) after controlling analyses for the effect of nm-VCO2.CONCLUSION: The current study suggests nm-VCO2 may moderate the relationship between recovery and PF and may have implications regarding AET induced buffering dynamics and its role in fatigue resistance during activity above moderate intensities.

Characterization of CO2 Expiration and its Relationship with Performance Fatigability in Adaptation to Chronic Exercise Perturbation

PurposeThis study characterized components of carbon dioxide expiration (VCO2) and their relationship with performance fatigability (PF) in adaptation to chronic exercise perturbation.Methods20 healthy men (n=9, age=44.7±13.9 ) and women (n=11, age=50.3±11.1) completed peak cardiopulmonary exercise (CPET) and constant work rate tests (CWRT) on separate days before and after a vigorous, 4‐week aerobic exercise training (AET) regimen. Each test was followed by 10‐minutes of passive recovery and an endurance test at 70% of the peak watts attainted during the CPET. PF was indexed by the endurance test durations following both the peak CPET (End1) and CWRT (End2), peak CPET time (pk‐Time), and peak CPET watts (pk‐Watts). Metabolic indices were calculated as total VO2 (tVO2), total VCO2 (tVCO2), metabolic VCO2 (m‐VCO2), and non‐metabolic VCO2 (nm‐VCO2). Data were analyzed for significant (p&lt;0.05) changes and determinant relationships using paired t‐tests, and Pearson coefficients of determination (r2).ResultsSignificant reductions (Table ) in PF measures along with significant increases in tVO2, tVCO2, and nm‐VCO2 were observed after AET. A change in m‐VCO2 was not observed. End1 (s) End2 (s) pk‐Time (s) pk‐Watts tVO2 (ml) tVCO2 (ml) m‐VCO2 (ml) nm‐VCO2 (ml) 265±337 p&lt;0.01* 321±392 p&lt;0.01* 63±40 p&lt;0.001* 24±19 p&lt;0.001* 1127±1569 p&lt;0.01* 1512±2225 p&lt;0.01* 904±2255 p=0.089 608±666 p&lt;0.001* nm‐VCO2 was strongly determinant of performance fatigability (pk‐Time r2=0.858, pk‐Watts r2=0.832, end1 r2=0.533, end2 r2=0.682, p&lt;0.001*).ConclusionThe current study demonstrated significant increases in the buffering component of total carbon dioxide expiration but not in the component associated with energy repletion. The buffering component was directly associated with measures of performance, providing plausibility that the buffering component may be a determinant of performance fatigability. End1 (s) End2 (s) pk‐Time (s) pk‐Watts tVO2 (ml) tVCO2 (ml) m‐VCO2 (ml) nm‐VCO2 (ml) 265±337 321±392 63±40 24±19 1127±1569 1512±2225 904±2255 608±666 p&lt;0.01* p&lt;0.01* p&lt;0.001* p&lt;0.001* p&lt;0.01* p&lt;0.01* p=0.089 p&lt;0.001*

Effects of Three Months of Detraining on the Health Profile of Older Women after a Multicomponent Exercise Program.

Physical exercise results in very important benefits including preventing disease and promoting the quality of life of older individuals. Common interruptions and training cessation are associated with the loss of total health profile, and specifically cardiorespiratory fitness. Would detraining (DT) promote different effects in the cardiorespiratory and health profiles of trained and sedentary older women? Forty-seven older women were divided into an experimental group (EG) and a control group (CG) (EG: n = 28, 70.3 ± 2.3 years; CG: n = 19, 70.1 ± 5.6 years). Oxygen uptake (VO2) and health profile assessments were conducted after the exercise program and after three months of detraining. The EG followed a nine-month multicomponent exercise program before a three-month detraining period. The CG maintained their normal activities. Repeated measures ANOVA showed significant increases in total heath and VO2 (p < 0.01) profile over a nine-month exercise period in the EG and no significant increases in the CG. DT led to greater negative effects on total cholesterol (4.35%, p < 0.01), triglycerides (3.89%, p < 0.01), glucose (4.96%, p < 0.01), resting heart rate (5.15%, p < 0.01), systolic blood pressure (4.13%, p < 0.01), diastolic blood pressure (3.38%, p < 0.01), the six-minute walk test (7.57%, p < 0.01), Pulmonary Ventilation (VE) (10.16%, p < 0.01), the Respiratory Exchange Ratio (RER) (9.78, p < 0.05), and VO2/heart rate (HR) (16.08%, p < 0.01) in the EG. DT may induce greater declines in total health profile and in VO2, mediated, in part, by the effectiveness of multicomponent training particularly developed for older women.

75 Assessment of allometric changes of visceral organs in pigs from birth to 10 kg bodyweight at 14 days post-weaning

Abstract Visceral organs (VO) play a crucial role in nutrient metabolism needed for growth and development. Although many studies have documented selected VO growth during early development or around the time of weaning, few studies have documented complete VO growth from birth through the post-weaning (PW) period. The objective of this study was to assess allometric changes of VO growth from birth through d 14 PW. Crossbred pigs were randomly assigned to slaughter (n = 6, 3 male and 3 female) for tissue collection at birth (pre-suckle), 1 and 7 days after birth, at weaning (20.0 ± 1.3 d), and days 1, 2, 5, 7, and 14 PW. Pigs were fed a common PW diet formulated to meet or exceed NRC (2012) estimates. Body weight (BW) and VO were collected and measured (Table 1). Data were analyzed by ANOVA using GLM procedure of SAS with linear and quadratic effects of age determined by contrast statements. BW, absolute small intestine length (SIL), and absolute large intestine length (LIL) increased (linear, P &lt; 0.001) with age. Absolute stomach, liver, pancreas, and total VO weight (including the previously mentioned organs in addition to heart, lungs, kidneys, and spleen) increased (linear and quadratic, P &lt; 0.0001) with pig age and BW. Relative weight (relative to BW) for stomach (0.52 - 0.82%, respectively), liver (2.99 - 3.17%, respectively), pancreas (0.14 - 0.22 %, respectively), and total VO weight (9.95 - 17.64%, respectively) also increased (linear and quadratic, P &lt; 0.0008) over time (d 0 - 14 PW). The SIL relative to total intestinal length (83.79 - 82.14%, respectively) and relative LIL (16.21 - 17.86, respectively) did not change (P &gt; 0.05) from birth to d 14 PW. In conclusion, the weight of the assessed VO increased hyperallometrically from birth to d 14 PW.

Exercise energy expenditure in patients with idiopathic pulmonary arterial hypertension: Impact on clinical severity and survival

Patient with idiopathic pulmonary hypertension (IPAH) develop peripheral inefficiency which could lead to an increase total energy expenditure and that could have a significant prognostic impact.To test the hypothesis, fifty-five consecutive stable IPAH patients (mean age 51±17 years) and 24 matched controls underwent an incremental exercise test and followed for a 5 years’ period. Total energy expenditure was assessed as the ratio between total VO2 uptake (during both effort and recovery) and total external work (VO2 TOT/WTOT).Patients with IPAH had a lower exercise capacity and a significantly higher VO2 TOT/WTOT than controls (VO2 TOT/WTOT 0.33 ± 0.09 ml/j vs 0.22 ± 0.04 ml/j, p < 0.0001). Among patients, VO2 TOT/WTOT was higher in whom died during follow up compared to survivors (0.41 ± 0.11 ml/j vs 0.30 ± 0.06 ml/j, p < 0.0001).In multivariate Cox regression analysis VO2 TOT/WTOT, gender, PETCO2 peak, V˙O2 peak were independent risk factors for death.Patients with IPAH have shown a less efficient muscular oxygen utilization than controls. Notably the high energy expenditure has a relevant independent prognostic impact.

Oxygen consumption, rate of perceived exertion and enjoyment in high-intensity interval eccentric cycling

The objectives of this article are to compare oxygen consumption (VO2) and perceptual responses between continuous and interval eccentric cycling protocols in order to test the hypothesis that metabolic demand and enjoyment would be greater for interval than continuous eccentric cycling protocols. Eleven recreationally active men (n = 9) and women (32.6 ± 9.4 years) performed a concentric cycling test to determine peak power output (PPO) followed by five eccentric cycling protocols on separate occasions: continuous eccentric cycling at 60% of PPO for 20 min at 60 rpm (CONT20@60%) and 13.2 min at 90 rpm (CONT13@60%), 4 × 4 min at 75% of PPO with 2-min rest (INT4×4@75%), 12 × 1 min at 100% of PPO with 1-min rest (INT1×12@100%) and 10 × 1 min at 150% of PPO with 1-min rest (INT1×10@150%). Gas exchange and power output were recorded continuously, and rate of perceived exertion (RPE) and enjoyment were assessed after each exercise. Total VO2 including the rest periods was the greatest (p < 0.0001) during INT1×10@150% (382 ± 73 ml kg−1) and lowest (p < 0.0001) during CONT13@60% (146 ± 27 ml kg−1). Total VO2 during INT1×12@100% (312 ± 59 ml kg−1) was greater (p < 0.0001) than CONT20@60% (246 ± 63 ml kg−1) and INT4×4@75% (257 ± 42 ml kg−1). RPE was greater (p < 0.0001) after INT1×10@150% (17 ± 2) than other conditions, but perceived enjoyment was not significantly different between protocols. It was concluded that the interval protocols increased metabolic demand without increasing RPE and enjoyment. It appears that high-intensity interval protocols can be used in eccentric cycling prescription.

Muscle Pain as a Regulator of Cycling Intensity: Effect of Caffeine Ingestion.

Caffeine ingestion improves endurance time trial performance. However, the ergogenic mechanism of action remains unresolved. One potential explanation for caffeine's performance-enhancing effect is an improvement in work for a given amount of muscle pain. To test this hypothesis, participants performed two studies in which they regulated exercise intensity based on feelings of muscle pain. Thirteen young men were asked to regulate exercise intensity based on feelings of "moderate" muscle pain (a "3" on a 0-10 pain scale). After three familiarization trials, either caffeine (∼ 5 mg · kg(-1) body weight) or placebo were administered before a moderate pain trial. Nine caffeine "responders" were retested and ask to regulate their exercise intensity at a "strong" pain level (a "5" on a 0-10 pain scale). A caffeine (∼ 5 mg · kg(-1) body weight) or placebo was again ingested before exercise. Participants performed more work (P = 0.008) and covered more distance (P = 0.008) at a higher average power output (P = 0.009) and VO2 (P = 0.019), for an identical amount of "moderate" muscle pain in the caffeine condition. When exercising at a rating of a "5," caffeine did not increase total work, distance covered, or VO2 for an identical amount of "strong" pain in the nine caffeine "responders." Our findings indicate caffeine increases work performed during exercise, eliciting a moderate amount of a pain. However, a threshold level of muscle pain may exist above which antagonism of adenosine receptors alone does not induce a hypoalgesic effect.

Strength and aerobic training in overweight females in Gdansk, Poland.

We compared the effects of 16-week-training on rest metabolic rate, aerobic power, and body fat, and the post-exercise effects upon rest oxygen uptake and respiratory exchange ratio in overweight middle-aged females. Twenty nine overweight women (BMI 29.9 ± 1.2 kg*m−2) participated in training (3 days a week). The subjects were divided onto groups of aerobic (AT) and strength (ST) training. The results showed that the total body mass decrease and VO2 max increase did not differ in both groups. Decrease in waist circumference after 16 weeks was higher in the ST group. In the ST group fat-free mass increased during the first 8 weeks. Rest metabolic rate was increased significantly at 16th week compared to initial value in ST group only. Significant increase in post-exercise resting VO2 and respiratory exchange ratio at 12 and 36 h was observed after the strength training session only. Increase in rest metabolic rate and post-exercise rest energy expenditure occurred after strength training but not after aerobic training despite the similar increase in aerobic power. The effect of 8–16 weeks of strength training on body mass decrease was higher in comparison to aerobic training.

Reliability and Validity of the Dutch Physical Activity Questionnaires for Children (PAQ-C) and Adolescents (PAQ-A).

BackgroundThis study was designed to validate the Dutch Physical Activity Questionnaires for Children (PAQ-C) and Adolescents (PAQ-A).MethodsAfter adjustment of the original Canadian PAQ-C and PAQ-A (i.e. translation/back-translation and evaluation by expert committee), content validity of both PAQs was assessed and calculated using item-level (I-CVI) and scale-level (S-CVI) content validity indexes. Inter-item and inter-rater reliability of 196 PAQ-C and 95 PAQ-A filled in by both children or adolescents and their parent, were evaluated. Inter-item reliability was calculated by Cronbach’s alpha (α) and inter-rater reliability was examined by percent observed agreement and weighted kappa (κ). Concurrent validity of PAQ-A was examined in a subsample of 28 obese and 16 normal-weight children by comparing it with concurrently measured physical activity using a maximal cardiopulmonary exercise test for the assessment of peak oxygen uptake (VO2 peak).ResultsFor both PAQs, I-CVI ranged 0.67-1.00. S-CVI was 0.89 for PAQ-C and 0.90 for PAQ-A. A total of 192 PAQ-C and 94 PAQ-A were fully completed by both child and parent. Cronbach’s α was 0.777 for PAQ-C and 0.758 for PAQ-A. Percent agreement ranged 59.9-74.0% for PAQ-C and 51.1-77.7% for PAQ-A, and weighted κ ranged 0.48-0.69 for PAQ-C and 0.51-0.68 for PAQ-A. The correlation between total PAQ-A score and VO2 peak – corrected for age, gender, height and weight – was 0.516 (p = 0.001).ConclusionsBoth PAQs have an excellent content validity, an acceptable inter-item reliability and a moderate to good strength of inter-rater agreement. In addition, total PAQ-A score showed a moderate positive correlation with VO2 peak. Both PAQs have an acceptable to good reliability and validity, however, further validity testing is recommended to provide a more complete assessment of both PAQs.Electronic supplementary materialThe online version of this article (doi:10.1186/2049-3258-72-47) contains supplementary material, which is available to authorized users.

Consumo de oxigênio durante ciclismo na máxima fase estável de lactato sanguíneo até a exaustão: modelo contínuo vs. intermitente

ObjectiveThe aim of this study was to analyse the accumulated oxygen uptake (VO2), as well the maintained time (TMcg) at high levels during a maximal lactate steady state (MLSS) exercise, determined in continuous (MLSScon) and intermittent (MLSSint) modes, until exhaustion. MethodFourteen trained cyclists performed an incremental maximal testing; 2‐5 continuous and 2‐4 intermittent constant workload trials, in order to identify the MLSScon and MLSSint, respectively; two tests until exhaustion (TTE) (continuous and intermittent) were conducted using their respective MLSS workloads. ResultsThe continuous TTE was significantly lower than TTE at intermittent protocol (54.7±10.9 vs. 67.8±14.3min; p=0.001). The VO2 at target workload (VO2cg) was higher at intermittent exercise (p<0.05), at both situations (MLSS and TTE). On the other hand, TMcg and the VO2 accumulated in MLSS workloads (VO2ACcg) were higher during continuous mode (p<0.0001), at both situations. The total VO2 accumulated (VO2ACt) was similar between intermittent and continuous cycling (MLSS: 104.7±8.7L vs. 103.9±41.1L and TTE: 193.8±41.1L vs. 226.4±53.0L, respectively). ConclusionWhen MLSS continuous and intermittent were performed with same duration or until exhaustion, the VO2ACt was similar, although the TMcg and VO2ACcg were smaller during intermittent exercise.