Peak Oxygen Research Articles

The independent effects of hypovolaemia and pulmonary vasoconstriction on ventricular function and exercise capacity during acclimatisation to 3800m.

We sought to determine the isolated and combined influence of hypovolaemia and hypoxic pulmonary vasoconstriction on the decrease in left ventricular (LV) function and maximal exercise capacity observed under hypobaric hypoxia. We performed echocardiography and maximal exercise tests at sea level (344m), and following 5-10days at the Barcroft Laboratory (3800m; White Mountain, California) with and without (i) plasma volume expansion to sea level values and (ii) administration of the pulmonary vasodilatator sildenafil in a double-blinded and placebo-controlled trial. The high altitude-induced reduction in LV filling and ejection was abolished by plasma volume expansion but to a lesser extent by sildenafil administration; however, neither intervention had a positive effect on maximal exercise capacity. Both hypovolaemia and hypoxic pulmonary vasoconstriction play a role in the reduction of LV filling at 3800m, but the increase in LV filling does not influence exercise capacity at this moderate altitude. We aimed to determine the isolated and combined contribution of hypovolaemia and hypoxic pulmonary vasoconstriction in limiting left ventricular (LV) function and exercise capacity under chronic hypoxaemia at high altitude. In a double-blinded, randomised and placebo-controlled design, 12 healthy participants underwent echocardiography at rest and during submaximal exercise before completing a maximal test to exhaustion at sea level (SL; 344m) and after 5-10days at 3800m. Plasma volume was normalised to SL values, and hypoxic pulmonary vasoconstriction was reversed by administration of sildenafil (50mg) to create four unique experimental conditions that were compared with SL values: high altitude (HA), Plasma Volume Expansion (HA-PVX), Sildenafil (HA-SIL) and Plasma Volume Expansion with Sildenafil (HA-PVX-SIL). High altitude exposure reduced plasma volume by 11% (P<0.01) and increased pulmonary artery systolic pressure (19.6±4.3 vs. 26.0±5.4, P<0.001); these differences were abolished by PVX and SIL respectively. LV end-diastolic volume (EDV) and stroke volume (SV) were decreased upon ascent to high altitude, but were comparable to sea level in the HA-PVX trial. LV EDV and SV were also elevated in the HA-SIL and HA-PVX-SIL trials compared to HA, but to a lesser extent. Neither PVX nor SIL had a significant effect on the LV EDV and SV response to exercise, or the maximal oxygen consumption or peak power output. In summary, at 3800m both hypovolaemia and hypoxic pulmonary vasoconstriction contribute to the decrease in LV filling, but restoring LV filling does not confer an improvement in maximal exercise performance.

Left ventricular function and exercise capacity after arterial switch operation for transposition of the great arteries: a systematic review and meta-analysis.

The arterial switch operation for transposition of the great arteries was initially believed to be an anatomical correction. Recent evidence shows reduced exercise capacity and left ventricular function in varying degrees in the long term after an arterial switch operation. To perform a meta-analysis on long-term exercise capacity and left ventricular ejection fraction after an arterial switch operation. A literature search was performed to cover all studies on patients who had undergone a minimum of 6 years of follow-up that reported either left ventricular ejection fraction, peak oxygen uptake, peak workload, and/or peak heart rate. A meta-analysis was performed if more than three studies reported the outcome of interest. A total of 21 studies reported on the outcomes of interest. Oxygen uptake was consistently lower in patients who had undergone an arterial switch operation compared with healthy controls, with a pooled average peak oxygen uptake of 87.5±2.9% of predicted. The peak heart rate was also lower compared with that of controls, at 92±2% of predicted. Peak workload was significantly reduced in two studies. Pooled left ventricular ejection fraction was normal at 60.7±7.2%. Exercise capacity is reduced and left ventricular ejection fraction is preserved in the long term after an arterial switch operation for transposition of the great arteries.

Sport-Specific Repeated Sprint Training Improves Punching Ability and Upper-Body Aerobic Power in Experienced Amateur Boxers

Kamandulis, S, Bruzas, V, Mockus, P, Stasiulis, A, Snieckus, A, and Venckunas, T. Sport-specific repeated sprint training improves punching ability and upper-body aerobic power in experienced amateur boxers. J Strength Cond Res 32(5): 1214-1221, 2018-High-intensity interval training improves endurance and performance, but it is unclear whether sprint-type upper-body interval training is similarly effective. This study explored the effects of 4-week sport-specific sprint interval training on punch characteristics and endurance capacity in boxers. Experienced male amateur boxers (n = 18) participated in this 4-week training study and were divided into an experimental group (EG) and a control group (CG) (n = 9 per group). Both groups completed standard low-intensity training. The EG also completed 3 rounds (14 sets of 3-second all-out punching with a 10-second rest) of a simulated fight using a punching bag with a 1-minute rest between rounds 3 times per week, whereas the CG performed the same 3 rounds of a simulated fight at low intensity. Three rounds of 14 sets of 3-second all-out punching of a bag ergometer with a 10-second rest were performed to measure punching abilities. Peak oxygen consumption and peak power were measured during progressive arm cranking before and after training. In response to training peak oxygen consumption and peak power in arm-cranking test increased in EG, also punching force increased and maintenance of punching frequency and punch force improved during the simulated fight, which resulted in greater cumulative force throughout the 3 rounds. There were no changes in the CG. The study shows that 1 month of all-out punching training (3 sessions per week with ∼2 minutes of all-out punching per session) improved both upper-body aerobic power and punching abilities in experienced amateur boxers.

The Effects of HIIT on Maximal Oxygen Uptake and Peak Power in Sedentary, Obese Women

The Effects of HIIT on Maximal Oxygen Uptake and Peak Power in Sedentary, Obese Women

Relative peak exercise oxygen pulse is related to sudden cardiac death, cardiovascular and all-cause mortality in middle-aged men.

Background Preliminary evidence suggests that peak exercise oxygen pulse - peak oxygen uptake/heart rate-, a variable obtained during maximal cardiopulmonary exercise testing and a surrogate of stroke volume, is a predictor of mortality. We aimed to assess the associations of peak exercise oxygen pulse with sudden cardiac death, fatal coronary heart disease and cardiovascular disease and all-cause mortality. Design A prospective study. Methods Peak exercise oxygen pulse was assessed in a maximal cycling test at baseline in 2227 middle-aged men of the Kuopio Ischaemic Heart Disease cohort study using expired gas variables and electrocardiograms. Relative peak exercise oxygen pulse was obtained by dividing the absolute value by body weight. Results During a median follow-up of 26.1 years 1097 subjects died; there were 220 sudden cardiac deaths, 336 fatal coronary heart diseases and 505 fatal cardiovascular diseases. Relative peak exercise oxygen pulse (mean 19.5 (4.1) mL per beat/kg/102) was approximately linearly associated with each outcome. Comparing extreme quartiles of relative peak exercise oxygen pulse, hazard ratios (95% confidence intervals) for sudden cardiac death, fatal coronary heart disease and cardiovascular disease, and all-cause mortality on adjustment for cardiovascular risk factors were 0.55 (0.36-0.83), 0.58 (0.42-0.81), 0.60 (0.46-0.79) and 0.59 (0.49-0.70), respectively ( P < 0.001 for all). The hazard ratios were unchanged on further adjustment for C-reactive protein and the use of beta-blockers. The addition of relative peak exercise oxygen pulse to a cardiovascular disease mortality risk prediction model significantly improved risk discrimination (C-index change 0.0112; P = 0.030). Conclusion Relative peak exercise oxygen pulse measured during maximal exercise was linearly and inversely associated with fatal cardiovascular and all-cause mortality events in middle-aged men. In addition, relative peak exercise oxygen pulse provided significant improvement in cardiovascular disease mortality risk assessment beyond conventional risk factors.

Effect of interfacial SiO2−y layer and defect in HfO2−x film on flat-band voltage of HfO2−x/SiO2−y stacks for backside-illuminated CMOS image sensors

In this study, the effect of oxygen gas fraction during deposition of a hafnium oxide (HfO2−x) film and the influence of the quality of the SiO2−y interlayer on the nature of flat-band voltage (Vfb) in TiN/HfO/SiO2−y/p-Si structures were investigated. X-ray photoemission spectroscopy analysis showed that the non-lattice oxygen peak, indicating an existing oxygen vacancy, increased as the oxygen gas fraction decreased during sputtering. From C–V and J–E analyses, the Vfb behavior was significantly affected by the characteristics of the SiO2−y interlayer and the non-lattice oxygen fraction in the HfO2−x films. The HfO2−x/native SiO2−y stack presented a Vfb of − 1.01 V for HfO2−x films with an oxygen gas fraction of 5% during sputtering. Additionally, the Vfb of the HfO2−x/native SiO2−y stack could be controlled from − 1.01 to − 0.56 V by changing the deposition conditions of the HfO2−x film with the native SiO2−y interlayer. The findings of this study can be useful to fabricate charge-accumulating layers for backside-illuminated image sensor devices.

Catalytic Oxidation of Hydrogen Sulfide on Fe/WSAC Catalyst Surface Modification via NH3-NTP: Influence of Gas Gap and Dielectric Thickness

Surface modification of the Fe/WSAC catalyst with NH3-NTP could enhance its catalytic oxidation ability toward H2S. Influences of discharge gaps and dielectric thicknesses were indicated. The H2S catalytic oxidation performance of Fe/WSAC catalyst was increased first and then decreased with increasing of discharge gap or dielectric thickness. The SEM images showed significant changes in the surface topography after treatment at low discharge gaps or large dielectric thicknesses, after which the surface was clear and smooth. The BET results showed that the surface area increased after the plasma treatment at low discharge gas gaps or large dielectric thicknesses. From the XPS spectra, the nitrogen content increased after the plasma treatment, and the deconvolution of the O 1s lattice oxygen peak revealed the oxygen content to increase at short discharge gas gaps. NH3-plasma treatment is an efficient modification method for the improvement of the catalytic oxidation performance of activated carbon catalysts.

Investigation of cardiopulmonary exercise testing using a dynamic leg press and comparison with a cycle ergometer

BackgroundLeg-press machines are widely employed for musculoskeletal conditioning of the lower-limbs and they provide cardiovascular benefits for resistance training in cardiac patients. The aim of this study was to assess the feasibility of a dynamic leg press (DLP) for incremental cardiopulmonary exercise testing (CPET) and to compare the results with those obtained using a cycle ergometer (CE).MethodsTwelve healthy participants aged 27±4 years (mean ± standard deviation) performed incremental cardiopulmonary exercise tests on a DLP and on a CE. To facilitate CPET, the DLP was augmented with force and angle sensors, a work rate estimation algorithm, and a visual feedback system. Gas exchange variables and heart rate were recorded breath-by-breath using a cardiopulmonary monitoring system.ResultsPeak oxygen uptake and peak heart rate were significantly lower for the DLP than for the CE: peak oxygen uptake was 3.2±0.5 vs. 4.1±0.5 L/min (DLP vs. CE, p=6.7×10−6); peak heart rate was 174±14 vs. 182±13 bpm (DLP vs. CE, p=0.0016). Likewise, the sub-maximal cardiopulmonary parameters, viz. the first and second ventilatory thresholds, and ramp duration were significantly lower for the DLP.ConclusionsThe dynamic leg press was found to be feasible for CPET: the approach was technically implementable and all peak and sub-maximal cardiopulmonary parameters were able to be identified. The lower outcome values observed with the DLP can be attributed to a peripheral factor, namely the earlier onset of muscular fatigue.

Peak Velocity as an Alternative Method for Training Prescription in Mice.

Purpose: To compare the efficiency of an aerobic physical training program prescribed according to either velocity associated with maximum oxygen uptake (vVO2max) or peak running speed obtained during an incremental treadmill test (Vpeak_K) in mice.Methods: Twenty male Swiss mice, 60 days old, were randomly divided into two groups with 10 animals each: 1. group trained by vVO2max (GVO2), 2. group trained by Vpeak_K (GVP). After the adaptation training period, an incremental test was performed at the beginning of each week to adjust training load and to determine the amount of VO2 and VCO2 fluxes consumed, energy expenditure (EE) and run distance during the incremental test. Mice were submitted to 4 weeks of aerobic exercise training of moderate intensity (velocity referring to 70% of vVO2max and Vpeak_K) in a programmable treadmill. The sessions lasted from 30 to 40 min in the first week, to reach 60 min in the fourth week, in order to provide the mice with a moderate intensity exercise, totaling 20 training sessions.Results: Mice demonstrated increases in VO2max (ml·kg−1·min−1) (GVO2 = 49.1% and GVP = 56.2%), Vpeak_K (cm·s−1) (GVO2 = 50.9% and GVP = 22.3%), EE (ml·kg−0,75·min−1) (GVO2 = 39.9% and GVP = 51.5%), and run distance (cm) (GVO2 = 43.5% and GVP = 33.4%), after 4 weeks of aerobic training (time effect, P < 0.05); there were no differences between the groups.Conclusions: Vpeak_K, as well as vVO2max, can be adopted as an alternative test to determine the performance and correct prescription of systemized aerobic protocol training to mice.

Different Training Modalities Improve Energy Cost and Performance in Master Runners.

Purpose: The aim of this study was to compare the effects of continuous moderate-intensity and discontinuous high-intensity training on running performance in master runners.Methods: Thirty-four male master runners (47.2 ± 7.4 years) were assigned to three different groups: continuous moderate-intensity training (CMIT), discontinuous high-intensity training (DHIT), and control group (CON). CMIT and DHIT performed 8-week of supervised training (3 session·wk−1; ~35 km·wk−1) while CON maintained their normal training habits (3–4 session·wk−1; ~50 km·wk−1). Peak oxygen consumption (O2peak) and peak running speed (vpeak) during incremental treadmill exercise, gas exchange threshold (GET), speed at GET, energy cost of running (Cr), and 5-km performance were evaluated before and after training.Results: Following the training period, both CMIT and DHIT significantly reduced Cr (−4.4 and −4.9%, respectively, P < 0.05), increased speed at GET (3.4 and 5.7%, P < 0.05) and improved 5-km time-trial performance (3.1 and 2.2%, P < 0.05) whereas no differences were found for O2peak and GET (as %O2peak). After training, vpeak improved only for DHIT (6%, P < 0.05). No differences were found in any variable for CON.Conclusions: This study indicates that both CMIT and DHIT may positively affect running performance in middle-aged master runners. This improvement was achieved despite a significant reduction of the amount of weekly training volume.

The Physiological Effects of Combined Training with Breathing Resistance and Sustained Physical Exertion in Healthy Young Adults

Purpose: The aim of the present study was to describe the physiological effects of a combined training with breathing resistance and sustained physical exertion (CBS) program, which is a respiratory muscle training program designed to improve respiratory function and cardiorespiratory endurance, in young adults.Methods: Pre-and post-intervention measurements were comparatively examined between a group that completed an endurance exercise training program combined with a breathing resistance component (CBS group) and a group that underwent an endurance exercise training program only (control group). Data for these participants were analyzed together with similar data obtained in a previous study, where the effects of the CBS program on the respiratory and circulatory systems of nine healthy young subjects were evaluated with preliminary position of present research. The participants of the present study additionally underwent measurements related to respiratory muscle endurance. All participants were healthy young men and women.Results: In total, 18 participants were analyzed. After the 6-week program, the maximum oxygen uptake and peak ventilatory threshold in the CBS group showed a significant improvement relative to the baseline measurements. The maximal voluntary ventilation and respiratory muscle endurance capacity also exhibited an improvement.Conclusions: The results of this study indicate that our CBS program improves respiratory function more effectively than conventional training programs. Furthermore, they strongly support the findings of our previous study, where it was reported that CBS improves cardiorespiratory endurance more effectively than conventional training programs. Condensed AbstractWe described the physiological effects of a combined training with breathing resistance and sustained physical exertion program in healthy young adults. The obtained data were combined with existing comparable data. We found that the improvements in respiratory muscle function and cardiorespiratory endurance were greater with our combined program than with conventional programs.

Carbohydrate mouth rinse reduces rating of perceived exertion but does not affect performance and energy systems contribution during a high-intensity exercise

ABSTRACT Aim The study aimed to verify the effect of carbohydrate (CHO) mouth rinse on time to exhaustion, energy systems contribution and rating of perceived exertion (RPE) during a high-intensity exercise. Methods Fourteen men performed an incremental exercise test to determine their maximal oxygen uptake and peak power output (PPO) and two time-to-exhaustion tests at 110% of PPO. Participants rinsed their mouth with 25ml of 6.4% of CHO or placebo (PLA) solution immediately before the time-to-exhaustion test, using a crossover design. The contribution of the energy systems was calculated using the free software GEDAE-LaB®. Results Time to exhaustion was similar between the conditions (CHO:174.3±42.8s; PLA:166.7±26.3s; p=0.33). In addition, there was no difference between the CHO and PLA condition for aerobic (CHO:135.1±41.2kJ and PLA:129.8±35.3kJ, p=0.34), anaerobic lactic (CHO:57.6±17.1kJ and PLA:53.4±15.1kJ, p=0.10), and anaerobic alactic (CHO:10.4±8.4kJ and PLA:13.2±9.2kJ, p=0.37) contribution. Consequently, total energy expenditure was similar between conditions (CHO:203.2±46.4kJ and PLA:196.5±45.2kJ, p=0.15). However, CHO mouth rinse reduced the RPE at the moment of exhaustion (CHO:18.2±1.0units and PLA:19.1±1.1units; p=0.02). Conclusion CHO mouth rinse neither increased time to exhaustion nor altered energy systems contribution during a high-intensity exercise, but reduced the perceived effort at the exhaustion.

Trp64Arg polymorphism of the ADRB3 gene associated with maximal fat oxidation and LDL-C levels in non-obese adolescents

ObjectiveTo analyze the association between the Trp64Arg polymorphism of the ADRB3 gene, maximal fat oxidation rates and the lipid profile levels in non-obese adolescents. Methods72 schoolchildren, of both genders, aged between 11 and 17 years, participated in the study. The anthropometric and body composition variables, in addition to total cholesterol, HDL-c, LDL-c, triglycerides, insulin, and basal glycemia, were evaluated. The sample was divided into two groups according to the presence or absence of the polymorphism: non-carriers of the Arg64 allele, i.e., homozygous (Trp64Trp: n=54), and carriers of the Arg64 allele (Trp64Arg+Arg64Arg: n=18), in which the frequency of the Arg64 allele was 15.2%. The maximal oxygen uptake and peak of oxygen uptake during exercise were obtained through the symptom-limited, submaximal treadmill test. Maximal fat oxidation was determined according to the ventilatory ratio proposed in Lusk's table. ResultsAdolescents carrying the less frequent allele (Trp64Arg and Arg64Arg) had higher LDL-c levels (p=0.031) and lower maximal fat oxidation rates (p=0.038) when compared with non-carriers (Trp64Trp). ConclusionsAlthough the physiological processes related to lipolysis and lipid metabolism are complex, the presence of the Arg 64 allele was associated with lower rates of FATMAX during aerobic exercise, as well as with higher levels of LDL-c in adolescents.

Growth Hormone Improves Cardiopulmonary Capacity and Body Composition in Children With Growth Hormone Deficiency.

Growth hormone deficiency (GHD) in children may be associated with early cardiovascular risk factors and alterations in left ventricular (LV) structure and function; data on cardiopulmonary functional capacity are lacking. Aim of the study was to evaluate the effect of GHD and growth hormone (GH) therapy on cardiopulmonary functional capacity, left and right cardiac structure and function, and body composition in children and adolescents. Prospective, case-control study. Twenty-one untrained GHD children (11.3 ± 0.8 years) underwent cardiopulmonary exercise testing, echocardiography and dual-energy x-ray absorptiometry, before and after 12 months of GH therapy. Twenty-one controls matched for sex, pubertal status, body mass index, and physical activity (PA) were evaluated at baseline and after 1 year. At baseline, GHD patients showed reduced LV mass (LVM; 63.32 ± 7.80 vs 80.44 ± 26.29 g/m2, P = 0.006), peak oxygen consumption (VO2peak; 22.92 ± 4.80 vs 27.48 ± 6.71 mL/Kg/min, P = 0.02), peak workload (80.62 ± 29.32 vs 103.76 ± 36.20 W, P = 0.02), and O2 pulse (4.93 ± 1.30 vs 7.67 ± 2.93 mL/beat, P = 0.0003), compared with controls. GHD patients also exhibited lower lean body mass (LBM 65.36 ± 7.84% vs 76.13 ± 8.23%, P < 0.001), and higher fat mass (FM 30.84 ± 7.92% vs 22.19 ± 8.18%, P = 0.001) than controls. GH therapy resulted in a significant increase of LVM (72.01 ± 15.88, P = 0.03), VO2peak (26.80 ± 4.97; P = 0.01), peak workload (103.67 ± 32.24, P = 0.001), O2 pulse (6.64 ± 1.68, P = 0.0007), and LBM (75.36 ± 7.59%, P = 0.0001), with a reduction in FM (22.62 ± 7.73%, P = 0.001). No difference was found in either left or right ventricular function. Our results suggest that cardiac structure, body composition and cardiopulmonary functional capacity are impaired in children with untreated GHD and can be restored after short-term GH replacement therapy.

Development of primary standard gas mixtures containing 10 µmol/mol oxygen in nitrogen with verification by a two-oven GC-TCD system for effective separation of oxygen from argon in presence of plenty of nitrogen

Primary standard gas mixtures (PSMs) containing 10 µmol/mol oxygen in nitrogen were prepared in aluminum alloy cylinders from pure nitrogen and oxygen gases according to ISO 6142-1. We developed a system consisting of a gas chromatograph with a thermal conductivity detector (GC-TCD) and two ovens to verify precisely the amount-of-substance fraction of oxygen in the PSMs at a level of 10 µmol/mol. As pure nitrogen gas usually contains argon as an impurity, it is necessary to separate the oxygen peak from the argon peak in order to verify the amount-of-substance fraction of oxygen in the PSMs. Although the use of packed columns is essential in order to achieve high precision using a GC-TCD system, it is notoriously difficult to separate oxygen and argon by this method. To overcome this problem, we used two gas chromatograph ovens: The first oven separates oxygen and argon from the nitrogen, whereas the second oven—held at −15 °C or below—separates oxygen and argon. The two-oven GC-TCD system was able to achieve good resolution between the oxygen and argon peaks. The relative uncertainty in the determination of the oxygen fraction obtained using this system was 0.35 %. In order to avoid adsorption of oxygen onto the inner surface of the aluminum cylinder, we pretreated each cylinder by filling it with a standard gas mixture of oxygen in nitrogen at an oxygen partial pressure similar to that of the PSMs. The cylinders were then evacuated and used for the preparation of the target PSMs. From long-term monitoring using the GC-TCD system, we found the PSMs containing 10 µmol/mol oxygen in nitrogen to be stable for at least 30 months. The expanded combined uncertainties for the PSMs (k = 2) were found to be 0.026 µmol/mol to 0.036 µmol/mol, according to ISO 6142-1.

The Effect of Using H4P2O7 as Phosphorus Source for Synthesizing Vanadyl Pyrophosphate Catalysts

&lt;p&gt;Vanadyl pyrophosphate (VO)&lt;sub&gt;2&lt;/sub&gt;P&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;7&lt;/sub&gt; catalysts synthesized via VOPO&lt;sub&gt;4&lt;/sub&gt;·2H&lt;sub&gt;2&lt;/sub&gt;O were investigated by using BET surface area measurement, X-ray Diffraction (XRD), Scanning Electron Microscope (SEM), and Temperature-Programmed Techniques (TPD and TPRS). H&lt;sub&gt;3&lt;/sub&gt;PO&lt;sub&gt;4&lt;/sub&gt; and H&lt;sub&gt;4&lt;/sub&gt;P&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;7&lt;/sub&gt; were used as the phosphorus source. Only pyrophosphate phase was observed for both final catalysts after 75 hours of calcination in a reaction flow of &lt;em&gt;n&lt;/em&gt;-butane/air mixture (0.75% &lt;em&gt;n&lt;/em&gt;-butane/air). However, catalyst derived from H&lt;sub&gt;4&lt;/sub&gt;P&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;7&lt;/sub&gt; based preparation (denoted VPD&lt;sub&gt;pyro&lt;/sub&gt;) exhibit better crystallinity and slightly higher BET surface area compared to the H&lt;sub&gt;3&lt;/sub&gt;PO&lt;sub&gt;4&lt;/sub&gt; based preparation (denoted VPD&lt;sub&gt;ortho&lt;/sub&gt;). The nature of the oxidants for both catalysts was investigated by O&lt;sub&gt;2&lt;/sub&gt;-TPD. For VPD&lt;sub&gt;pyro&lt;/sub&gt;, TPD showed an oxygen peak maximum at 986 K and a shoulder at 1003 K, whereas for VPD&lt;sub&gt;ortho&lt;/sub&gt;, the oxygen was desorbed as two peaks maxima at 966 and 994 K. The total amount of oxygen desorbed thermally from VPD&lt;sub&gt;pyro&lt;/sub&gt; (3.60×10&lt;sup&gt;20&lt;/sup&gt; atom×g&lt;sup&gt;-1&lt;/sup&gt;) is higher than that obtained for VPD&lt;sub&gt;ortho&lt;/sub&gt; (3.07×10&lt;sup&gt;20&lt;/sup&gt; atom×g&lt;sup&gt;-1&lt;/sup&gt;). VPD&lt;sub&gt;pyro&lt;/sub&gt; displayed a slightly improved activity and selectivity for &lt;em&gt;n&lt;/em&gt;-butane oxidation. A proper amount of V&lt;sup&gt;5+&lt;/sup&gt; species may have an effect on the enhancement of the catalytic activity.&lt;/p&gt;

Physiological Profile and Activity Pattern of Minor Gaelic Football Players.

Cullen, BD, Roantree, M, McCarren, A, Kelly, DT, O'Connor, PL, Hughes, SM, Daly, PG, and Moyna1, NM. Physiological profile and activity pattern of minor Gaelic football players. J Strength Cond Res 31(7): 1811-1820, 2017-The purpose of this study was to evaluate the physiological profile and activity pattern in club- and county-level under-18 (U-18) Gaelic football players relative to playing position. Participants (n = 85) were analyzed during 17 official 15-a-side matches using global positioning system technology (SPI Pro X II; GPSports Systems, Canberra, Australia) and heart rate (HR) telemetry. During the second part of this study, 63 participants underwent an incremental treadmill test to assess their maximal oxygen uptake (V[Combining Dot Above]o2max) and peak HR (HRmax). Players covered a mean distance of 5,774 ± 737 m during a full 60-minute match. The mean %HRmax and %V[Combining Dot Above]O2max observed during the match play were 81.6 ± 4.3% and 70.1 ± 7.75%, respectively. The playing level had no effect on the distance covered, player movement patterns, or %HRmax observed during match play. Midfield players covered significantly greater distance than defenders (p = 0.033). Playing position had no effect on %HRmax or the frequency of sprinting or high-intensity running during match play. The frequency of jogging, cruise running, striding (p = 0.000), and walking (p = 0.003) was greater in the midfield position than in the forward position. Time had a significant effect (F(1,39) = 33.512, p-value = 0.000, and (Equation is included in full-text article.)= 0.462) on distance covered and %HRmax, both of which showed a reduction between playing periods. Gaelic football is predominantly characterized by low-to-moderate intensity activity interspersed with periods of high-intensity running. The information provided may be used as a framework for coaches in the design and prescription of training strategies. Positional specific training may be warranted given the comparatively greater demands observed in the midfield playing position. Replicating the demands of match play in training may reduce the decline in distance covered and %HRmax observed during the second half of match play.

Stability of nanoclusters in an oxide dispersion strengthened alloy under neutron irradiation

Here, we report atom probe tomography results of the nanoclusters in a neutron-irradiated oxide dispersion strengthened alloy. Following irradiation to 5dpa at target temperatures of 300°C and 450°C, fewer large nanoclusters were found and the residual nanoclusters tend to reach an equilibrium Guinier radius of 1.8nm. With increasing dose, evident decrease in peak oxygen and titanium (but not yttrium) concentrations in the nanoclusters was observed, which was explained by atomic weight, solubility, diffusivity, and chemical bonding arguments. The chemical modifications indicate the equilibrium size is indeed a balance of two competing processes: radiation enhanced diffusion and collisional dissolution.

The effect of adenotonsillectomy on obstructive sleep apnea in children with Down syndrome

Objective: Children with Down syndrome (DS) are liable to develop obstructive sleep apnea (OSA) due to many anatomical airway abnormalities. The tonsils and adenoid occupy part of the airway space, and their removal may be helpful in relieving airway obstruction. The aim of this study was to assess the effectiveness of adenotonsillectomy in the treatment of OSA in those children.Methods: Fifty DS children with difficult breathing were recruited, and they were subjected to polysomnographic examination (PSG). Patients with apnea-hypopnea index (AHI) > 1 were considered to have OSA. Adenotonsillectomy was performed for patients who had OSA and adenotonsillar hypertrophy, and after 3 months PSG was done for them with recording of the same preoperative parameters.Results: Forty-three children demonstrated OSA on PSG, and they were included in the study. The preoperative mean AHI was 9.18 (± 6.17) that improved postoperatively to 2.72 (± 3.80) with its normalization in 72% of patients. Also, significant improvement of arousal index, minimum oxygen saturation, desaturation index, and peak end-tidal CO2 was achieved postoperatively.Conclusion: Adenotonsillectomy is an effective method for the treatment of OSA in children with DS. However, the condition may persist in some children who usually have airway narrowing at multiple levels.

The associations of cardiorespiratory fitness, adiposity and sports participation with arterial stiffness in youth with chronic diseases or physical disabilities.

BackgroundThe evidence on the associations of cardiorespiratory fitness, body adiposity and sports participation with arterial stiffness in children and adolescents with chronic diseases or physical disabilities is limited.MethodsAltogether 140 children and adolescents with chronic diseases or physical disabilities participated in this cross-sectional study. Cardiorespiratory fitness was assessed using maximal exercise test with respiratory gas analyses either using shuttle run, shuttle ride, or cycle ergometer test. Cardiorespiratory fitness was defined as peak oxygen uptake by body weight or fat-free mass. Body adiposity was assessed using waist circumference, body mass index standard deviation score and body fat percentage. Sports participation was assessed by a questionnaire. Aortic pulse wave velocity and augmentation index were assessed by a non-invasive oscillometric tonometry device.ResultsPeak oxygen uptake/body weight (standardised regression coefficient β −0.222, 95% confidence interval (CI) −0.386 to −0.059, P = 0.002) and peak oxygen uptake/fat-free mass (β −0.173, 95% CI −0.329 to −0.017, P = 0.030) were inversely and waist circumference directly (β 0.245, 95% CI 0.093 to 0.414, P = 0.002) associated with aortic pulse wave velocity. However, the associations of the measures of cardiorespiratory fitness with aortic pulse wave velocity were attenuated after further adjustment for waist circumference. A higher waist circumference (β −0.215, 95% CI −0.381 to −0.049, P = 0.012) and a higher body mass index standard deviation score (β 0.218, 95% CI −0.382 to −0.054, P = 0.010) were related to lower augmentation index.ConclusionsPoor cardiorespiratory fitness and higher waist circumference were associated with increased arterial stiffness in children and adolescents with chronic diseases and physical disabilities. The association between cardiorespiratory fitness and arterial stiffness was partly explained by waist circumference.