Measurement Of Oxygen Uptake Research Articles

Norwegian upper secondary students’ experiences of their teachers’ assessment of and for learning in physical education: examining how assessment is interpreted by students of different physical abilities

ABSTRACT Teachers’ assessment enhances students’ learning in many situations in physical education (PE). The present study aims to examine the issue of potential unequal assessment of students due to their different physical abilities in PE in upper secondary school, where the research question is: What experiences do students with high or low levels of physical fitness have of their PE teacher’s assessment of and for learning? Individual interviews were conducted with thirteen boys and thirteen girls in the second year in upper secondary school to answer the question. Respondents were recruited on the basis of scores on physical fitness tests (measurement of oxygen uptake). Thirteen respondents scored on the lowest level and thirteen on the highest level of the fitness scale. Two main themes emerged from the analysis, revealing an unequal assessment of learning given to the students in the two groups, but a shared, equal experience of assessment for learning. Unfortunately, assessment for learning was experienced ‘rarely or never’, and the unequal assessment of learning did not favour the students with low physical fitness, who perhaps need more assessment than the students with high physical fitness. The study contributes new insight into students’ experience of assessment due to unequal conditions for learning. The analysis revealed elements that were lacking in the PE teaching and assessment, especially for the students with low physical fitness. Another finding is that few students experienced that they owned their learning process, even though some students experienced to be in a learning environment, wherein the teacher gave them learning-promoting assessment. The study reinforces the finding in earlier research to integrate assessment for learning in theories of teaching in PE, and from this perspective we support further exploration of assessment for learning as well as the concept of assessment literacy.

Effect of Dynamic Hyperinflation on Cardiac Response to Exercise of Patients With Chronic Obstructive Pulmonary Disease

IntroductionAlthough the major limitation to exercise performance in patients with COPD is dynamic hyperinflation (DH), little is known about its relation with cardiac response to exercise. Our objectives were to compare the exercise response of stroke volume (SV) and cardiac output (CO) between COPD patients with or without DH and control subjects, and to assess the main determinants. MethodsFifty-seven stable COPD patients without cardiac comorbidity and 25 healthy subjects were recruited. Clinical evaluation, baseline function tests, computed tomography and echocardiography were conducted in all subjects. Patients performed consecutive incremental exercise tests with measurement of operating lung volumes and non-invasive measurement of SV, CO and oxygen uptake (VO2) by an inert gas rebreathing method. Biomarkers of systemic inflammation and oxidative stress, tissue damage/repair, cardiac involvement and airway inflammation were measured. ResultsCOPD patients showed a lower SV/VO2 slope than control subjects, while CO response was compensated by a higher heart rate increase. COPD patients with DH experienced a reduction of SV/VO2 and CO/VO2 compared to those without DH. In COPD patients, the end-expiratory lung volume (EELV) increase was related to SV/VO2 and CO/VO2 slopes, and it was the only independent predictor of cardiac response to exercise. However, in the regression models without EELV, plasma IL-1β and high-sensitivity cardiac troponin T were also retained as independent predictors of SV/VO2 slope. ConclusionDynamic hyperinflation decreases the cardiac response to exercise of COPD patients. This effect is related to systemic inflammation and myocardial stress but not with left ventricle diastolic dysfunction.

Kinetics of oxygen uptake during unassisted breathing trials in prolonged mechanical ventilation: a prospective pilot study

Few studies have investigated the measurement of oxygen uptake ({dot{text{V}}}O2) in tracheostomized patients undergoing unassisted breathing trials (UBTs) for liberation from mechanical ventilation (MV). Using an open-circuit, breath-to-breath method, we continuously measured {dot{text{V}}}O2 and relevant parameters during 120-min UBTs via a T-tube in 49 tracheostomized patients with prolonged MV, and calculated mean values in the first and last 5-min periods. Forty-one (84%) patients successfully completed the UBTs. The median {dot{text{V}}}O2 increased significantly (from 235.8 to 298.2 ml/min; P = 0.025) in the failure group, but there was no significant change in the success group (from 223.1 to 221.6 ml/min; P = 0.505). In multivariate logistic regression analysis, an increase in {dot{text{V}}}O2 > 17% from the beginning period (odds ratio [OR] 0.084; 95% confidence interval [CI] 0.012–0.600; P = 0.014) and a peak inspiratory pressure greater than − 30 cmH2O (OR 11.083; 95% CI 1.117–109.944; P = 0.04) were significantly associated with the success of 120-min UBT. A refined prediction model combining heart rate, energy expenditure, end-tidal CO2 and oxygen equivalent showed a modest increase in the area under the receiver operating characteristic curve of 0.788 (P = 0.578) and lower Akaike information criterion score of 41.83 compared to the traditional prediction model including heart rate and respiratory rate for achieving 48 h of unassisted breathing. Our findings show the potential of monitoring {dot{text{V}}}O2 in the final phase of weaning in tracheostomized patients with prolonged MV.

Oxygen Pulse Is Reduced In Individuals With Down Syndrome

Individuals with Down syndrome (DS) have lower peak oxygen uptake (VO2peak) in comparison to individuals without DS. This is partly explained by autonomic dysfunction with lower peak heart rates observed during maximal exercise in DS compared to controls. Oxygen (O2) pulse is the measure of oxygen uptake per heartbeat and is a product of stroke volume and arterial-venous difference. As such, it is widely used as an indicator of deconditioning and could provide unique information about exercise intolerance in individuals with DS. PURPOSE: To compare O2 pulse between individuals with DS and a sex- and age-matched control group. METHODS: Individuals with DS (n=17; male n=11; age (mean± standard deviation) = 25 ± 4 years) and controls (n=17; male, n =11; age 24 ± 3 years) completed a maximal exercise treadmill test with a previously validated protocol. Heart rate and oxygen uptake were averaged over 15-second intervals. O2 pulse was calculated by dividing peak oxygen uptake by peak heart rate. Group differences were analyzed with independent t-tests. RESULTS: Individuals with DS had lower height, absolute VO2peak (p<.001), relative VO2peak (p<0.001), peak heart rate (p<0.001), and O2 pulse (p= 0.017) compared to controls. CONCLUSION: Individuals with DS demonstrated lower O2 pulse in comparison to individuals without DS, potentially explained by deconditioning or population-specific physiologic limitations. This research is partly supported by NIH K99R01 HD092606-01.Data presented as mean ± standard deviation. BMI: Body Mass Index, RER: Respiratory Exchange Ratio, HR: Heart Rate, VO2: Oxygen Uptake * p < 0.05

Efficacy of a Six-Week Dispersed Wingate-Cycle Training Protocol on Peak Aerobic Power, Leg Strength, Insulin Sensitivity, Blood Lipids and Quality of Life in Healthy Adults.

Background: The aim of this study was to evaluate the efficacy of a six-week dispersed Wingate Anaerobic test (WAnT) cycle exercise training protocol on peak aerobic power (VO2peak), isokinetic leg strength, insulin sensitivity, lipid profile and quality of life, in healthy adults. Methods: We conducted a match-controlled cohort trial and participants were assigned to either the training (intervention, INT, N = 16) or non-training (control, CON, N = 17) group. INT performed 30-s WAnT bouts three times a day in the morning, afternoon and evening with each bout separated by ~4 h of rest, performed for 3 days a week for 6 weeks. Criterion measures of peak oxygen uptake (VO2peak), leg strength, insulin markers such as homeostatic model assessment (HOMA) and quantitative insulin-sensitivity check index (QUICKI), blood lipids profile and health-related quality of life (HRQL) survey were assessed before and after 6 weeks in both groups. Results: Absolute VO2peak increased by 8.3 ± 7.0% (p < 0.001) after INT vs. 0.9 ± 6.1% in CON (p = 0.41) group. Maximal voluntary contraction at 30°·s−1 of the dominant lower-limb flexors in INT increased significantly post-training (p = 0.03). There were no changes in the INT individuals’ other cardiorespiratory markers, HOMA, QUICKI, blood lipids, and HRQL measures (all p > 0.05) between pre- and post-training; but importantly, no differences were observed between INT and CON groups (all p > 0.05). Conclusions: The results indicate that 6 weeks of dispersed sprint cycle training increased cardiorespiratory fitness and dynamic leg strength but had minimal impact on insulin sensitivity, blood lipids and quality of life in the exercising individuals.

Energy Cost Of Selected Household Physical Activities In Adults

According to the 2018 American Time Use Survey, nearly 78% of US adults spend from 2.0-2.5 hours/day in housework activities that include cleaning, laundry, straightening up, cooking, washing dishes and other activities. Another 11% of adults spend nearly 1.0 hour/day caring for older household adults. As many adults do household activities, there is interest in knowing the energy costs of such activities. PURPOSE: To update the MET values in the 2011 Adult Compendium of Physical Activities (Compendium) with measured oxygen uptake MET values for selected household physical activities (PAs) in adults. METHODS: The energy costs of six meal-related, five household cleaning, and two other care PAs were measured in 20 adults ages 20-59 (10 males, 10 females). Each simulated PA was performed in a laboratory setting for 8-min with a 4-min rest between PAs. Submaximal VO2 (ml/kg/min) and heart rate (beats/min) were measured with a Cosmed K4b2 portable indirect calorimetry system. METs were computed as VO2 in ml/kg/min divided by 3.5 ml/kg/min. Subjects self-rated their PA and physical fitness level as low, middle or high. RESULTS: Subject characteristics were averaged for age (33.7 + 11.2 yrs.), weight (67.9 + 12.0 kg), and height (166.1 + 7.4 cm). MET values were averaged up or down to reflect terminal digit values as presented in the 2011 Compendium (0, 3, 5, 8). MET values: carrying groceries on level surface (3.5), putting away groceries (2.5), food prep and cooking while standing (1.8), food prep and cooking while sitting (1.8), setting the table (2.3), clearing the table and washing dishes (2.0), folding and putting away laundry (2.0), putting away household items (3.0), major cleaning (3.0), sweeping sidewalk (3.0), watering plants (1.8), other care feeding/grooming (1.8), other care bathing/dressing (2.8). Heart rates ranged from 74 to 92 beats/min across all PAs. PA and fitness levels were rated as middle. CONCLUSIONS: Measured MET values were generally lower (on the order of 0.3 to 1.2 METs) than estimated MET values presented in the 2011 Compendium. Measured MET values were the same as the 2011 Compendium for putting away groceries and putting away household items. Overall, measured MET values for frequently performed household activities are rated as low- to moderate intensity. Supported by the Shanghai University of Sport

Exercise Training Effects on the Relationship of Physical Function and Health-Related Quality of Life Among Older Heart Failure Patients With Preserved Ejection Fraction.

Although exercise training (ET) has been shown to improve both physical function and health-related quality of life (HRQOL) in older patients with heart failure and preserved ejection fraction (HFpEF), the relationship between changes in these important patient-centered outcome measures has not been adequately investigated. Patients (n = 116) with HFpEF (from 2 previous randomized controlled trials) were assigned to either 16 wk of endurance ET or attention control (CON). The ET in both trials consisted of ≤ 60 min of moderate-intensity endurance ET 3 time/wk. Peak exercise oxygen uptake (V˙o2peak) and other exercise capacity measures were obtained from a cardiopulmonary exercise test on an electronically braked cycle ergometer and 6-min walk test (6MWT). HRQOL was assessed using the Minnesota Living with Heart Failure (MLHF) Questionnaire and the 36-item Short Form Health Survey (SF-36). Compared with CON, the ET group demonstrated significant improvement in measures of physical function (V˙o2peak and 6MWT) at 16 wk of follow-up. There were no significant differences observed between the groups for MLHF scores, but the ET group showed significant improvements on the SF-36. There were no significant correlations between change in any of the physical function and HRQOL measures in the ET group. While endurance ET improved both physical function and some domains of HRQOL, the lack of significant correlations between changes in these measures suggests the effects of ET on physical function and HRQOL are largely independent of one another. Since these measures assess important and unique patient-centered outcomes in HFpEF patients, both physical function and HRQOL should be assessed in exercise-based programs and clinical trials.

Warburg’s method as a simple tool for measuring oxygen uptake in spray-dried emulsions

• An apparatus was built to measure the oxygen uptake of FO and spray-dried emulsions. • Oxygen consumption was correlated with physicochemical properties. • WPI and GE-contaning powders presented higher oxidative stability MS-powders. Lipid oxidation is usually responsible for oil downgrading of spray-dried powders and it is strongly dependent on the storage conditions. Direct measurements of the oxygen uptake using cost-effective methods combined with the study of water adsorption of the powders allow evaluating their barrier properties against oxidation. Therefore, a low-cost and simple apparatus based on the Warburg’s manometric technique was built, and its results were compared to Rancimat and Oxipres methods. Firstly, free unsaturated oil (fish oil) was evaluated and data showed a strong positive correlation between the oxygen uptakes for the new apparatus (0.015 mL O 2 /h) and Oxipres method (Pearson’s coefficient = 0.97). After, different surface-active compounds (SAC) (whey protein isolate – WPI, gelatin – GE, or modified starch – MS) mixed to maltodextrin (MD) were used to encapsulate the fish oil via spray drying. The lowest oxygen uptake was obtained by MD + WPI (0.0018 mL O 2 /h), followed by MD + GE (0.0103 mL O 2 /h) and MD + MS (0.0291 mL O 2 /h), with similar behavior obtained by Rancimat method. The lowest protective barrier of MD + MS-powders was confirmed by the comparatively higher susceptibility to water adsorption, and consequently the lower glass transition temperature (∼58.7 °C at water activity = 0.3−0.4). This study presented a successful creation of an apparatus to provide useful, fast and effective information about oxygen consumption by fish oil and encapsulated fish oil, allowing the understanding of the protection of SAC against oxidation in spray-dried emulsions. The proposed apparatus can be easily implemented in laboratories, with potential application for other oxygen-sensitive products.

The effects of stride frequency manipulation on physiological and perceptual responses during backward and forward running with body weight support.

We investigated the influence of a change in stride frequency on physiological and perceptual responses during forward and backward running at different body weight support (BWS) levels. Participants ran forward and backward at 0% BWS, 20% BWS, and 50% BWS conditions on a lower body positive pressure treadmill. The stride frequency conditions consisted of forward and backward running at preferred stride frequency (PSF), PSF + 10%, and PSF-10%. We measured oxygen uptake ([Formula: see text]O2), carbon dioxide production, heart rate (HR), muscle activity from the lower extremity, and rating of perceived exertion (RPE). Furthermore, we calculated the metabolic cost of transport (CoT). [Formula: see text]O2, HR, CoT, and muscle activity from the rectus femoris were significantly different between stride frequency conditions (P < 0.05). [Formula: see text]O2, HR, and CoT during running at PSF + 10% were significantly higher than when running at PSF, regardless of running direction and BWS (P < 0.05). However, RPE was not different between stride frequency conditions (P > 0.05: e.g., 12.8-13.8 rankings in RPE for backward running at 0% BWS). Manipulation of stride frequency during running may have a greater impact on physiological responses than on perceptual responses at a given speed, regardless of running direction and BWS. Individuals who need to increase their physiological demands during running may benefit from a 10% increase in stride frequency from the PSF, regardless of BWS and running direction.

Non-invasive estimation of stroke volume during exercise from oxygen in heart failure patients.

In heart failure, oxygen uptake and cardiac output measurements at peak and during exercise are important in defining heart failure severity and prognosis. Several cardiopulmonary exercise test-derived parameters have been proposed to estimate stroke volume during exercise, including the oxygen pulse (oxygen uptake/heart rate). Data comparing measured stroke volume and the oxygen pulse or stroke volume estimates from the oxygen pulse at different stages of exercise in a sizeable population of healthy individuals and heart failure patients are lacking. We analysed 1007 subjects, including 500 healthy and 507 heart failure patients, who underwent cardiopulmonary exercise testing with stroke volume determination by the inert gas rebreathing technique. Stroke volume measurements were made at rest, submaximal (∼50% of exercise) and peak exercise. At each stage of exercise, stroke volume estimates were obtained considering measured haemoglobin at rest, predicted exercise-induced haemoconcentration and peripheral oxygen extraction according to heart failure severity. A strong relationship between oxygen pulse and measured stroke volume was observed in healthy and heart failure subjects at submaximal (R2 = 0.6437 and R2 = 0.6723, respectively), and peak exercise (R2 = 0.6614 and R2 = 0.5662) but not at rest. In healthy and heart failure subjects, agreement between estimated and measured stroke volume was observed at submaximal (-3 ± 37 and -11 ± 72 ml, respectively) and peak exercise (1 ± 31 and 6 ± 29 ml, respectively) but not at rest. In heart failure patients, stroke volume estimation and oxygen pulse during exercise represent stroke volume, albeit with a relevant individual data dispersion so that both can be used for population studies but cannot be reliably applied to a single subject. Accordingly, whenever needed stroke volume must be measured directly.

Allometrically scaled explosive strength, but not static strength or maximal oxygen uptake is associated with better central processing time in young males.

We aimed to examine the associations of cardiorespiratory fitness (CRF), static strength and explosive strength with cognitive functions in young males. Eighty-six young males (age 16-24 years) participated in the study and took part in a number of tests including: static strength (grip strength test), explosive strength (Sargent jump test), and CRF (via direct measure of maximal oxygen uptake [VO2max]). Static strength and explosive strength were scaled by allometrically modeled skeletal muscle mass (SMM) and height while VO2max was scaled by SMM and body mass (BM). Cognition was assessed by inhibitory control, simple and choice reaction time tasks using computerized Cambridge Neuropsychological Test Battery (CANTAB). Central processing time was measured by surface electromyography changes in isometric contraction response to an audio stimulus. VO2max scaled by BM (but not SMM), was associated with better central processing time and stop-signal reaction time (SSRT). Explosive strength was also associated with better central processing time independent of VO2max. However, static strength was not associated with cognition. The results suggest that explosive strength is a better predictor of central processing than static strength or VO2max in young males. Longitudinal studies are needed to examine whether explosive strength training in youth would improve central processing time.

Exercising control over signs and symptoms of stress and depression

300 million people worldwide suffer from depression. A poorly understood stress‐related pathophysiology is compounded by frequent treatment‐resistance.Undertaking regular exercise has consistently shown to prevent, protect and increase resilience against the development of aberrant stress‐related responses seen in depression, whereas sedentary behaviour tends to heighten symptoms. Despite the promise shown by exercise its clinical use is undermined by poor understanding of how beneficial effects are produced.Stress exposure can dysregulate important physiological pathways such as the hypothalamic‐pituitary‐adrenal (HPA) axis and the sympathetic nervous system. Disruption of tryptophan metabolism, including increased metabolism along the kynurenine pathway, is a neurobiological hallmark of depressed patients. Recent studies have shown that the beneficial impact of exercise for mood and cognition may be linked to reduced kynurenine production.Aimto examine the benefits of a 12‐week exercise programme in healthy but sedentary adults across mood, stress, anxiety and depression were mediated by the regulation of tryptophan metabolism in a dose dependent manner.32 healthy sedentary participants (16 female) were analysed. To establish a baseline profile each participant undertook a battery of psychometric assessments, cognitive assessments and a cycle ergometer‐based incremental fitness assessment. Measures of oxygen uptake and capillary blood lactate levels were taken at the end of each stage during the fitness assessment.After the baseline assessment, participants were randomised into one of four groups (high, moderate, low dose exercise, or sedentary control group). Exercise was administered over 3 sessions/week based on individual fitness and group. Monthly fitness and psychometric assessments were performed throughout to monitor change across the 12‐week exercise programme. Analyses performed using SPSS.As expect, participants showed a positive increase in fitness and performance with an increase in maximal oxygen uptake (F(1,28)=14.62, p=.001, ηp2=.343) after 12‐weeks exercise training, accompanied by an increased relative peak power output (rPPO) (F(1,28)=16.93, p=.000, ηp2=.377) and an increased time to exhaustion (T2Ex) (F(1,28)=31.07, p=.000, ηp2=.526). Post hoc paired T‐tests revealed that the most pronounced effects on rPPO and T2Ex occurred in the moderate or high intensity groups There was a reduction in scores on the Beck Depression Inventory (BDI) (F(1,28)=6.50, p=.017, ηp2=.189) and the Perceived Stress Scale (PSS) (F(1,28)=4.09, p=.053, ηp2=.127) scores after 12 weeks of exercise.In sum, these results confirm that exercise training beneficially influences measures of stress and depression. Further work is required to understand the role of exercise‐induced alterations in tryptophan metabolism in mediating these effects.Support or Funding InformationAPC Microbiome Ireland is a research center funded by Science Foundation Ireland (SFI), through the Irish Government’s National Development Plan (grant no. 12/RC/2273). GC, JFC and TD are supported by the Irish Health Research Board (Grant number ILP‐POR‐2017‐013). CEG is supported by European Foundation for the Advancement in Neurosciences, Geneva, Switzerland.

Agreement between ACSM’s equation and cardiopulmonary exercise test in determine maximal oxygen uptake in individuals with metabolic syndrome

PurposeLow functional capacity is associated with cardiovascular risk factors. Cardiopulmonary exercise test (CPET) is the gold standard evaluation to determine functional capacity through maximal oxygen uptake (VO2max) measurement. However, the high financial cost, the material and the time spent on this method difficult its use in a large number of clinicals. In this sense, it is possible to determine VO2max via the equivalence formulas. The aim of this study was to verify the agreement between indirect calculation of VO2max using American College of Sports Medicine (ACSM) equation and the directly measure of maximal oxygen uptake in metabolic syndrome (MetS) patients.MethodsSixty non‐diabetic and without medication patients with MetS (ATP‐III) were divided in 2 groups, according to gender: Male (n=32; 46±9 y; 31.2±3.0 kg/m2); and Female (n=28; 49±9 y; 32.7±3.1 kg/m2). VO2max was measured during CPET in a cycle ergometer with ramp protocol and estimated by ACSM’s equation [VO2= 7.0+ (1.8 x work rate)/body mass].ResultsAll patients included achieved respiratory exchange rate (RER=VCO2/VO2) &gt;1.10 at maximal exercise. In Male group, despite correlation between methods (R=0.78; P=0.0001), VO2max estimated by ACSM’s equation was higher than the VO2max of the direct measurement (28.7±3.1 vs. 26.9±6.0 ml/kg/min; P=0.049). Similarly, in Female group there was correlation (R=0.79; P=0.0001), however VO2max estimated by ACSM’s equation was higher than direct measured VO2max (20.3±3.3 vs. 18.8±3.3 ml/kg/min; P=0.0008). In both genders, Bland‐Altman plot analysis suggested a lack of agreement between predicted and direct VO2max.ConclusionIn bout groups, Male and Female, the ACSM’s equation overestimates the VO2max. It seems that ACSM’s equation is not capable of accurately predicting VO2max in men and women with MetS.

Long-term effects of ivacaftor on nonpulmonary outcomes in individuals with cystic fibrosis, heterozygous for a S1251N mutation.

ObjectivesTo describe the long‐term effects of ivacaftor (Kalydeco®) in individuals with cystic fibrosis (CF) on body mass index (BMI), body composition (BC), pulmonary function (PF), resting energy expenditure (REE), and exercise capacity (EC) after ≥12 months of treatment.Working HypothesisBMI, lean and fat mass, PF, and EC will increase and REE will decrease after treatment.Study DesignObservational study.MethodologySeven individuals with CF (mean age 15.4 ± 5.8 years) heterozygous for S1251N mutation, starting with ivacaftor, were included. Paired t tests were performed to assess the effects of ivacaftor. Height and weight were used to calculate BMI and BMI Z‐scores. Dual‐energy X‐ray absorptiometry was used to assess BC. Spirometry and body plethysmography were used to assess PF. Indirect calorimetry was used to measure REE and cardiopulmonary exercise testing (CPET) was used to measure oxygen uptake (VO2peak), peak work rate (Wpeak), and other CPET variables.ResultsAfter a median of 15 (interquartile range: 13‐16) months of treatment, BMI increased significantly (P = .03), but not BMI Z‐score (P = .23) or BC. Significant improvements were found for several PF variables, especially measures of hyperinflation (P = .02). Absolute VO2peak (P = .01), VO2peak related to body weight (P = .00), and oxygen cost of work (P = .01) decreased. Absolute Wpeak (P = .59) and Wpeak related to body weight (P = .31) remained stable.ConclusionsThe results showed that long‐term treatment of ivacaftor is associated with improvement of BMI and PF, but not of BC and REE. Oxygen uptake reduced after treatment, which may be due to a decrease in work of breathing.

Estimating an individual's oxygen uptake during cycling exercise with a recurrent neural network trained from easy-to-obtain inputs: A pilot study.

Measurement of oxygen uptake during exercise () is currently non-accessible to most individuals without expensive and invasive equipment. The goal of this pilot study was to estimate cycling from easy-to-obtain inputs, such as heart rate, mechanical power output, cadence and respiratory frequency. To this end, a recurrent neural network was trained from laboratory cycling data to predict values. Data were collected on 7 amateur cyclists during a graded exercise test, two arbitrary protocols (Prot-1 and -2) and an “all-out” Wingate test. In Trial-1, a neural network was trained with data from a graded exercise test, Prot-1 and Wingate, before being tested against Prot-2. In Trial-2, a neural network was trained using data from the graded exercise test, Prot-1 and 2, before being tested against the Wingate test. Two analytical models (Models 1 and 2) were used to compare the predictive performance of the neural network. Predictive performance of the neural network was high during both Trial-1 (MAE = 229(35) mlO2min-1, r = 0.94) and Trial-2 (MAE = 304(150) mlO2min-1, r = 0.89). As expected, the predictive ability of Models 1 and 2 deteriorated from Trial-1 to Trial-2. Results suggest that recurrent neural networks have the potential to predict the individual response from easy-to-obtain inputs across a wide range of cycling intensities.

Disadvantages of Automated Respiratory Gas Exchange Analyzers.

The use of automated gas exchange analysis systems in exercise studies is common throughout the industrialized world and are frequently used in sports medicine laboratories for the measurement of maximal oxygen uptake (VO2max), as an integrative parameter that allows the physical condition to be assessed, in spite of its limitations. Actually, the fundamental principles behind the measurement of respiratory gas exchange (RGE) have not changed for a century. It was used a manual Douglas bag method together with separate chemical analyses. The need for faster and more efficient techniques, has conditioned the traditional procedures and determined the emergence of automated systems. However, the validity and reliability of all these different systems is not well known. The common features associates with these systems, also have disadvantages that must be evaluated at the time of the acquisition of an automated equipment: (1) regular quality control checks, which entails other added economic costs, (2) the validity and reliability of the results, which it is necessary to verify, and (3) the user does not know the equations that determine the values of oxygen consumption and carbon dioxide production. This work aims to clarify the disadvantages of these automated systems. At maximum intensities, the variation of VO2max or VO2peak can be very significant in athletes and even more relevant in sick people undergoing a training program. Therefore, considerable care is needed when comparing RGE data with automated systems.New and NoteworthyActually, stress tests are more conveniently performed with automated systems. It is necessary to examine the validity and reliability of automated respiratory gas exchange systems. The algorithms incorporated in the software, apart from being a “mystery,” show differences with respect to the data provided.

Reproducibility of Different Methodologies to Calculate Oxygen Consumption and Oxygen Cost During Walking in Chronic Stroke Survivors

Objective: The most common methods to calculate energy costs are based on measured oxygen uptake during walking a standardized distance or time. Unfortunately, it is unclear which method is most reliable to determine energy cost of walking in stroke survivors. The objective of this study was to evaluate the 3 most commonly used methods for calculating oxygen consumption and -cost by assessing test-retest reliability and measurement error in community dwelling chronic stroke survivors during a 6 Minute Walk Test. Methods: In this secondary analysis of a longitudinal study, reproducibility of the outcome of walking distance, walking speed, oxygen consumption and oxygen cost from 3 methods (Kendall's tau, assumed steady-state and total walking time oxygen consumption) were determined using Intraclass Correlation Coefficient, Standard Error of Measurement and Smallest Detectable Change. Results:20 from the 31 participants successfully performed the 6 minute walk test-retest within a timeframe of 1 month. Within the 2 tests the reproducibility of walking distance and walking speed was high. The 3 methods to determine reproducibility for oxygen cost and oxygen consumption were considered good (Kendall's tau), good (assumed steady-state) and excellent (total walking time). Conclusions: The method using oxygen consumption and -cost over the total walking time resulted in the highest reproducibility considering the Intraclass Correlation Coefficient, its 95% Confidence Interval, and smaller absolute differences.

Enzyme response of activated sludge to a mixture of emerging contaminants in continuous exposure.

The relevant information about the impacts caused by presence of emerging pollutants in mixtures on the ecological environment, especially on the more vulnerable compartments such as activated sludge (AS) is relatively limited. This study investigated the effect of ibuprofen (IBU) and triclosan (TCS), alone and in combination to the performance and enzymatic activity of AS bacterial community. The assays were carried out in a pilot AS reactor operating for two-weeks under continuous dosage of pollutants. The microbial activity was tracked by measuring oxygen uptake rate, esterase activity, oxidative stress and antioxidant enzyme activities. It was found that IBU and TCS had no acute toxic effects on reactor biomass concentration. TCS led to significant decrease of COD removal efficiency, which dropped from 90% to 35%. Continuous exposure to IBU, TCS and their mixtures increased the activities of glutathione s-transferase (GST) and esterase as a response to oxidative damage. A high increase in GST activity was associated with non-reversible toxic damage while peaks of esterase activity combined with moderate GST increase were attributed to an adaptive response.

A method for studying the metabolic activity of individual tardigrades by measuring oxygen uptake using microrespirometry.

Studies of tardigrade biology have been severely limited by the sparsity of appropriate quantitative techniques, informative on a single-organism level. Therefore, many studies rely on motility-based survival scoring and quantifying reproductive success. Measurements of O2 respiration rates, as an integrating expression of the metabolic activity of single tardigrades, would provide a more comprehensive insight into how an individual tardigrade is responding to specific environmental factors or changes in life stages. Here, we present and validate a new method for determining the O2 respiration rate (nmolO2mg-1h-1) of single tardigrades under steady state, using O2 microsensors. As an example, we show that the O2 respiration rate determined in MilliQ water for individuals of Richtersius coronifer and of Macrobiotus macrocalix at 22°C was 10.8±1.84 and 13.1±2.19 nmol O2mg-1h-1, respectively.

Respiration rates of herring larvae at different salinities, and effects of previous environmental history

Metabolic rates of early life history stages of marine fishes show considerable inter-individual differences, and are highly influenced by extrinsic factors like temperature or food availability. Measuring oxygen uptake rates is a proxy for estimating metabolic rates. Still, the relationship between respiration rates and ambient or previous salinity conditions as well as parental and developmental acclimation to changes in salinity remains largely unexplored. In the present study, we conducted experiments to investigate the effects of salinity on the routine metabolic rates (RMR) of euryhaline Atlantic herringClupea harenguslarvae at 3 levels of salinity: low (6 psu), intermediate (16 psu) and high (35 psu), reflecting ecologically relevant conditions for herring populations in the Atlantic Ocean and Baltic Sea. The larvae originated from different genetic backgrounds and salinity adaptations to account for cross-generation effects on metabolic rates. Closed respirometry carried out over 24 h on individual fish larvae generally confirmed near isometric respiration rates at all salinity regimes, with rates being 15.4% higher at 6 psu and 7.5% higher at 35 psu compared to 16 psu conditions. However, transgenerational acclimation to different salinity regimes of the parents had no effect on the salinity-specific metabolic rates of their offspring. Our study demonstrates the ability of herring to cope with a wide range of salinity conditions, irrespective of parental environmental history and genetic origin. This phenotypic plasticity is considered to be one of the main contributing factors to the success of herring as a widely distributed fish species in the North Atlantic and adjacent waters.