Oxygen Uptake Research Articles

The effect of ischemic preconditioning on physical fitness and performance: a meta-analysis in healthy adults.

This meta-analysis aims to assess the impact of ischemic preconditioning (IPC) on physical fitness and performance, with a focus on its specific role in aerobic endurance, anaerobic endurance, explosive power and strength. Systematic searches were conducted across multiple databases (CNKI, CBM, Cochrane Library, Web of Science, PubMed, and Embase) up to September 6, 2023. We included studies that employed randomized controlled trial methods and sham ischemic preconditioning as the placebo group, and two reviewers independently screened literature and extracted data, using Review Manager 5.3 for analysis. This meta-analysis comprises 27 articles with 405 individuals, selected according to specified criteria. IPC significantly increased the blood lactate concentration after anaerobic speed endurance exercise (MD = 0.74, P = 0.03), the blood lactate concentration after incremental exercise (MD = 0.49, P = 0.04), the blood lactate concentration after muscular endurance exercise (MD = 0.68, P = 0.02), and the one-repetition maximum (MD = 1.38, P = 0.00001). Furthermore, it also significantly shortened completion time of the exercises primarily powered by glycolysis (MD = - 0.49, P = 0.01) and completion time of the exercises primarily powered by aerobic system (MD = - 7.27, P = 0.05), while marginally prolonging time to exhaustion (MD = 22.68, P = 0.08). However, IPC had no significant effect on maximum oxygen uptake, blood lactate concentration in fixed-load aerobic endurance exercise, peak power, or peak aerobic power, nor on completion time of the exercises primarily powered by phosphagen system. IPC could serve as a method to enhance physical performance, particularly for exercises primarily powered by aerobic system and glycolysis. Future research might explore how various cycles, locations, and widths of IPC affect the physical performance of participants with different activity levels.

Comparing cadence-based energy expenditure and oxygen cost indices in able-bodied male people.

Walking is a fundamental aspect of daily life and exercise, with clinical benefits for cardiovascular health and muscle strength. However, accurately measuring energy efficiency during walking poses challenges due to equipment and spatial constraints. In this study, we proposed the cadence-based energy expenditure index (cEEI) and analyzed its correlation with the previously proposed index for measuring energy expenditure under various gait conditions. We enrolled 15 healthy participants and conducted an experimental protocol on a treadmill to measure the following energy expenditure-related indices: oxygen cost index (OCI), energy expenditure index (EEI), and cEEI. The participants underwent stages of walking at different speeds and inclinations that comply with the modified Bruce protocol while their heart rate, oxygen uptake, and cadence were recorded. Participants showed significant increases in heart rate, oxygen uptake, and cadence with higher walking speeds and inclinations. Correlation analysis revealed strong associations between cEEI and OCI, especially during walking conditions. Bland-Altman plots and interclass correlation coefficient analysis demonstrated a favorable agreement between cEEI and OCI, outperforming EEI. In conclusion, this study proposes cEEI as a reliable metric for estimating energy expenditure during walking by proving a strong correlation and agreement with OCI across various gait conditions. This suggests the potential for cEEI to provide real-time, individualized feedback on energy expenditure during walking, facilitating more personalized exercise prescriptions.

Confidence intervals estimator of the kinetic parameters: do its reliability depend on the assembling method of the oxygen uptakes?

Gas exchange data acquired repeatedly under the same exercise conditions are assembled together to improve the kinetic parameters of breath-by-breath oxygen uptake. The latter are provided by the non-linear regression procedure, together with the corresponding estimators of the width of the Confidence Intervals (i.e., the Asymptotic Standard Errors; ASEs). We tested, for two different assembling procedures, whether the range of values identified by the ASE actually correspond to the 95% Confidence Interval. Ten O2 uptake responses were acquired on 10 healthy volunteers performing a square-wave moderate-intensity exercise. Kinetic parameters were estimated running the non-linear regression with a mono-exponential model on an increasingly greater number of responses (Nr, from 1 to 10), assembled together using the "stacking" and the "1-s-bins" procedures. Kinetic values obtained assembling together the 10 repetitions were assumed as "true" values. The time constant was not affected by Nr or by the assembling procedure (ANOVA; p>0.54 and p>0.16, respectively). The corresponding ASE decreased according to Nr (ANOVA; p=0.000), being significantly smaller for the "1-s-bins" procedure compared to the "stacking" one (ANOVA; p<0.001). Excluding 20s at the start of the fitting window, the range of values identified with the ASE provided by the "1-s-bins" and the "stacking" procedures included the "true" value in 85% and in 95% of cases, respectively. The "stacking" procedure should be preferred since it yielded ASEs for the time constant that provided a range of values satisfying the statistical meaning of the width of the Confidence Intervals, at the given degree of probability.

Effectiveness of lower limb robotic rehabilitation on peak of oxygen uptake among patients with stroke: a systematic review and meta-analysis

ObjectivesTo evaluate the effectiveness of lower limb robotic rehabilitation (LLRR) on cardiovascular health among individuals with stroke undergoing rehabilitation.DesignSystematic reviews and meta-analysis.Data sourcesPubMed, Web of Science, Science Direct, Embase, China...

Effect of Sarcobesity Index and Body Adipose Tissue Variables on Cardiopulmonary Exercise Testing Performance in Colorectal Surgery Setting: A Retrospective Cohort Study.

Aims/Background The prognostic significance of body composition variables has become a popular area of research over the recent years. This study aimed to determine whether adipose tissue variables and sarcobesity index measured by computed tomography (CT) could predict cardiopulmonary exercise testing (CPET) performance and long-term mortality in patients undergoing major colorectal surgery. Methods The Strengthening the Reporting of Cohort Studies in Surgery (STROCSS) statement standards were followed to conduct a retrospective cohort study of consecutive patients who had CPET prior to major colorectal surgery between January 2011 and January 2017. Receiver Operating Characteristic curve analysis was conducted to assess the discriminative performances of adipose tissue variables. The association between CT-derived adipose tissue variables (sarcobesity index, visceral adipose tissue, subcutaneous adipose tissue, and total adipose tissue) and CPET performance and mortality were assessed using regression analyses. Results 457 patients were included. Total adipose tissue evaluated via 2-dimensional (2D) and 3-dimensional (3D) approaches predicted oxygen uptake (V̇O2) Rest, V̇O2 anaerobic threshold (AT), ventilatory equivalents for carbon dioxide (V̇E/V̇CO2) AT, ventilatory equivalents for oxygen (V̇E/V̇O2) AT, V̇O2 peak, exercise time, maximum work, peak metabolic equivalents (METS), peak respiratory rate (RER), and peak oxygen pulse. Sarcobesity index (2D and 3D) predicted V̇O2 Rest, V̇O2 AT, V̇E/V̇CO2 AT, V̇O2 peak, maximum work, peak METS, maximum heart rate, and peak RER. Neither total adipose tissue nor sarcobesity index (2D and 3D) predicted 1-year, 3-year, or 5-year mortality. There was no difference in the discriminative performance of adipose tissue variables in predicting mortality. Conclusion The CPET performance may be predicted by radiologically measured adipose tissue variables and sarcobesity index. However, the prognostic value of the variables may not be significant in this setting.

Does greater adherence to a healthy dietary pattern correspond to a better body composition and cardiorespiratory fitness in adults with overweight and primary hypertension? Data from the EXERDIET-HTA study.

Cardiovascular events are positively associated with primary hypertension (HTN), obesity, and low cardiorespiratory fitness (CRF) and negatively with healthy dietary patterns, such as Healthy Diet Indicator (HDI), Mediterranean diet (MD), and the Dietary Approaches to Stop Hypertension (DASH). The aim is to analyze the association between healthy dietary patterns with body composition and CRF. Body composition (bioimpedance) and CRF [peak oxygen uptake (V̇O2peak)] were assessed in 165 participants with HTN and overweight/obesity. There were (1) a positive association (unadjusted) between fat-free mass (%) with DASH and MD (P = 0.03) and a negative association between fat mass (%) and MD (P = 0.03); (2) positive associations (adjusted) between V̇O2peak (l·min-1) with DASH (P = 0.007), HDI (P = 0.017), and MD (P = 0.010) and V̇O2peak (ml·kg-1·min-1) with DASH (P = 0.005); (3) a negative relationship (unadjusted and adjusted) between energy intake and DASH (P = 0.004). In conclusion, these findings highlight the cardiovascular health protection provided by healthy dietary patterns associated with healthier CRF and body composition in people with a profile of HTN and overweight.

Acute cardiovascular responses of postmenopausal women to resistance training sessions differing in set configuration: A study protocol for a crossover trial.

Resistance training is hardly recommended for postmenopausal women to counteract negative effects of hormonal changes. However, some concern exists about the marked hemodynamic responses caused by high-load resistance exercises. In this regard, studies on young, healthy, physically active individuals suggest that set configuration can modulate acute cardiovascular, metabolic, and cardiac autonomic responses caused by resistance training sessions, but this has not yet been explored in postmenopausal women. A sample of 60 physically active postmenopausal women (30 normotensive, 30 hypertensive) will participate in this crossover study. After a medical exam, ergometry, familiarization session, and two testing sessions, participants will complete three experimental sessions and one control session in a randomized order. Each experimental session includes 36 repetitions of four exercises (horizontal leg press, bench press, prone leg curl, and lat pull-down) differing in set configuration: 9 sets of 4 repetitions (i.e., 33% intensity of effort) with 45 s of inter-set recovery, 6 sets of 6 repetitions (50% intensity of effort) with 72 s, and 4 sets of 9 repetitions (75% intensity of effort) with 120 s; with 4 min rest between exercises. Before and immediately after each session, arterial stiffness, hemodynamic variables, cardiac autonomic modulation, baroreflex sensitivity, sympathetic vasomotor tone, and resting oxygen uptake will be evaluated. Furthermore, perceived effort, mechanical performance (e.g., power, velocity), heart rate, and lactatemia will be collected throughout sessions. The impact of set configuration on these variables will be analyzed, along with comparisons between normotensive and hypertensive women. Cardiovascular responses to resistance exercise have been scarcely studied in females, particularly postmenopausal women. The results of this study will provide information about the modulating role of set structure on metabolic and cardiovascular responses of normotensive and hypertensive postmenopausal women to resistance training. NCT05544357 on 7 December 2022.

The Relationship between Inflammatory Factors, Hemoglobin, and VO2 Max in Male Amateur Long-Distance Cross-Country Skiers in the Preparation Period

Background: Identifying factors affecting heart health in amateur athletes can significantly impact their health and help them achieve high performance. The current knowledge of these predictors is insufficient. The purpose of this study was to identify the biochemical determinants of maximal oxygen uptake (VO2 max) in male amateur long-distance cross-country skiers (37.9 ± 6.58 years, 51.08 ± 4.61 VO2 max ml/kg/min) in the preparation period. Methods: In this cross-sectional study, a time trial test was used to determine VO2 max and venous blood via biochemical markers. Descriptive statistics and Pearson correlation were used to analyze the data. The regression model determined the predictors. Results: VO2 max was significantly correlated with nine moderate or weak variables. Two regression models (R2 = 0.94 and R2 = 0.9) each identified two determinants of VO2 max, hemoglobin (p &lt; 0.001) and C-reactive protein (p &lt; 0.001), as well as erythrocyte sedimentation (p &lt; 0.001) and platelets (p = 0.03). Only hemoglobin positive affected VO2 max. Conclusions: The results may indicate, in addition to results regarding hemoglobin concentration and its changes, the necessity to monitor the immune system, which may affect the capacity for amateur exercise. Biochemical monitoring is an essential tool for evaluating the individual adaptation to exercise and developing an effective training plan. The application of this knowledge can facilitate the achievement of optimal individual performance capabilities among cross-country skiing amateurs.

Impairment of Cardiovascular Functional Capacity in Mild-to-Moderate Kidney Dysfunction.

Traditional diagnostic tools that assess resting cardiac function and structure fail to accurately reflect cardiovascular alterations in patients with chronic kidney disease (CKD). This study sought to determine whether multidimensional exercise response patterns related to cardiovascular functional capacity can detect abnormalities in mild-to-moderate CKD. In a cross-sectional study, we examined 3,075 participants from the Framingham Heart Study (FHS) and 451 participants from the Massachusetts General Hospital Exercise Study (MGH-ExS) who underwent cardiopulmonary exercise testing (CPET). Participants were stratified by estimated glomerular filtration rate (eGFR): eGFR ≥90; eGFR 60-89; eGFR 30-59. Our primary outcomes of interest were peak oxygen uptake (VO 2 Peak),VO 2 at anaerobic threshold (VO 2 AT), and the ratio of minute ventilation to carbon dioxide production (VE/VCO 2 ). Multiple linear regression models were fitted to evaluate the associations between eGFR group and each outcome variable adjusted for covariates. In the FHS cohort, N=1,712 (56%) had an eGFR ≥90 ml/min/1.73m 2 , N=1,271 (41%) had an eGFR 60-89 ml/min/1.73m 2 , and N=92 (3%) had an eGFR 30-59 ml/min/1.73m 2 . In the MGH-ExS cohort, N=247 (55%) had an eGFR ≥90 ml/min/1.73m 2 , N=154 (34%) had an eGFR 60-89 ml/min/1.73m 2 , and N=50 (11%) had an eGFR 30-59 ml/min/1.73m 2 . In FHS, VO 2 Peak and VO 2 AT were incrementally impaired with declining kidney function ( p <0.001); however this pattern was attenuated following adjustment for age. Percent-predicted VO 2 Peak at AT was higher in the lower eGFR groups ( p <0.001). In MGH-ExS, VO 2 Peak and VO 2 AT were incrementally impaired with declining kidney function in unadjusted and adjusted models ( p <0.05). VO 2 Peak was associated with eGFR ( p <0.05) in all models even after adjusting for age. On further mechanistic analysis, we directly measured cardiac output (CO) at peak exercise via right heart catheterization and found impaired CO in the lower eGFR groups ( p ≤0.007). CPET-derived indices may detect impairment in cardiovascular functional capacity and track cardiac output declines in mild to moderate CKD.

Effects of acetazolamide on exercise performance in patients with COPD going to high altitude: randomised controlled trial

BackgroundIn patients with chronic obstructive pulmonary disease (COPD), preventive treatment with acetazolamide reduces adverse health effects during altitude travel. We investigated whether preventive acetazolamide treatment modifies exercise performance in COPD patients going to high altitude.MethodsIn this randomized, double-blind trial, lowlanders with COPD, FEV1 40–80%predicted, were assigned to acetazolamide (375 mg/24 h) or placebo treatment starting 24 h before ascent and while staying at 3100 m. Patients performed progressive cycling exercise to exhaustion at 760 m, before taking the study drug, and within 4 h after arrival at 3100 m. Primary outcome was the maximal power output (Wmax). ClinicalTrials.govNCT03177837.Results103 patients (32 women), mean ±sdage 57.2±8.1y, FEV1 66±11% predicted, were included in per protocol analyses. In 53 patients receiving acetazolamide, Wmax and oxygen uptake (V'O2max) at 760 m and 3100 m were 105±40 and 91±40watts, and 18.0±6.8 and 15.5±6.8 ml·min−1·kg−1(p&lt;0.001, both changes). Corresponding Wmax and V'O2max in 50 patients receiving placebo were 107±41 and 97±41watts, and 18.9±7.0 and 17.2±7.0 ml·min−1·kg−1(p&lt;0.001, both changes). Between-group differences (95%CI) in altitude-induced Wmax-changes were −3.0 watts (−8.7 to +2.7, p=0.305) and in V'O2max-changes were −0.8 ml·min−1·kg−1(−2.1 to +0.5, p=0.213). Acetazolamide mitigated the altitude-induced reduction of end-exercise PaO2by 0.7kPa (0.1 to 1.3, p=0.016). At 3100 m, maximal work rate with respiratory exchange ratio ≤1 was greater with acetazolamide than with placebo by 10.1 watts (4.0 to 16.2, p=0.022).ConclusionsIn lowlanders with COPD, preventive treatment with acetazolamide did not modify the altitude-induced reduction in maximal work rate. However, acetazolamide enhanced arterial oxygenation and submaximal, moderate-intensity work capacity compared to placebo.

Rhythm and rate control strategies in patients with long-standing persistent atrial fibrillation treated with cardiac resynchronization: the results of the randomized Pilot-CRAfT study.

Atrial fibrillation (AF) is common in cardiac resynchronization therapy (CRT) recipients. It is a marker of impaired CRT response mainly mediated by the reduction of effectively captured biventricular paced beats (BiVp). There are no randomized trials comparing strategies to maintain high BiVp percentage. To compare the efficacy of rhythm vs rate control strategies in CRT recipients with long-standing persistent AF. We performed a randomized trial including CRT recipients with persistent AF resulting in low BiVp%. All patients received amiodarone, the rhythm control group received external electrical cardioversion (EC), and the rate control group received atrioventricular node ablation, if needed. The primary end-point was 12-month BiVp% (NCT). 43 patients were included in the analysis. The mean age was 68.4 (SD: ± 8.3) years and the mean BiVp% 82.4% ± 9.7%. AF lasted 25 ± 19 months. The mean baseline left ventricular ejection fraction (LVEF), left atrium area, and the maximal oxygen uptake (VO2max) were: 30 ± 8%, 33 ± 7 cm2, and 14 ± 5 mL/(kg*min), respectively. The EC success rate was 58%. 38% patients remained in sinus rhythm (SR) after 12 months. BiVp% increased similarly in both arms reaching 99% [95% CI 97.3-99.8] and 98% [94.0-99.0], P = 0.14 in rhythm and rate control groups, respectively. LVEF raised significantly only in the rhythm control group (ΔLVEF 4.1 (± 7.3), P = 0,018) which was driven by the patients who maintained SR. No differences in VO2max, QoL, clinical and safety end-points were observed. Despite comparable BiVp% in both groups, only restoration of SR led to improved left ventricular ejection fraction in CRT patients with long-standing AF. NCT01850277 registered on 22/04/2013.

The influence of temperature on oxygen uptake of red alga Hildenbrandia rivularis – the next step of the indicatory potential revision

Hildenbrandia rivularis belongs to the freshwater red algae and is cosmopolitan. In some European countries, this species is protected, e.g., in Poland, where it mainly inhabits highly oxygenated, fast-flowing ecosystems. This alga is often considered both a bioindicator of oligotrophic waters and a relatively rare species in Europe. However, the expansion and ecological tolerance of H. rivularis have increased over the last decades; thus, there is an urgent call to retest its environmental optima and significance for bioindicative potential. In this paper, H. rivularis from Welna River (Poland) growing on hard substrates was tested. In addition to genetic, microscopic, and physicochemical analyses, we also delivered for the first time the relationship between the transient temperature changes (15 – 45 °C, with 5 °C intervals) and oxygen uptake of H. rivularis (based on ex situ measurements of O2 consumption by thalli). Interestingly, for the eurythermal H. rivularis, at the lowest temperature (15 °C) treatment, the O2 uptake was undetectable, but the respiratory rate reached maximal velocity at the two highest temperatures (40 and 45 °C). Importantly, the respiration of this alga was relatively stable across temperature gradient 20 – 35 °C. This observation could explain why this species has been disappearing from colder waters of uplands and mountains and started to prefer warmer lowland water ecosystems. The further increase in global warming can significantly accelerate this tendency, thus causing a significant change in the H. rivularis distribution pattern known from the previous literature. Finally, our research sheds new light on the bioindicative potential of H. rivularis.

The higher the fraction of maximal oxygen uptake is during interval training, the greater is the cycling performance gain.

It has been suggested that time at a high fraction (%) of maximal oxygen uptake (VO2max) plays a decisive role for adaptations to interval training. Yet, no study has, to date, measured the % of VO2max during all interval sessions throughout a prolonged training intervention and subsequently related it to the magnitude of training adaptations. Thus, the present study aimed to investigate the relationship between % of VO2max achieved during an interval training intervention and changes in endurance performance and its physiological determinants in well-trained cyclists. Twenty-two cyclists (VO2max 67.1 (6.4) mL·min-1·kg-1; males, n=19; females, n=3) underwent a 9-week interval training intervention, consisting 21 sessions of 5×8-min intervals conducted at their 40-min highest sustainable mean power output (PO). Oxygen uptake was measured during all interval sessions, and the relationship between % of VO2max during work intervals and training adaptations were investigated using linear regression. A performance index was calculated from several performance measures. With higher % of VO2max during work intervals, greater improvements were observed for maximal PO during the VO2max test (R2 adjusted=0.44, p=0.009), PO at 4mmol·L-1 [blood lactate] (R2 adjusted=0.25, p=0.035), the performance index (R2 adjusted=0.36, p=0.013), and VO2max (R2 adjusted=0.54, p=0.029). Other measures, such as % of maximal heart rate, were related to fewer outcome variables and exhibited poorer session-to-session repeatability compared to % of VO2max. In conclusion, improvements in endurance measures were positively related to the % of VO2max achieved during interval training. Percentage of VO2max was the measure that best reflected the magnitude of training adaptations.

Exercise testing in patients with tricuspid regurgitation undergoing transcatheter tricuspid valve intervention.

Transcatheter tricuspid valve intervention (TTVI) has shown promising results with persistent reduction of tricuspid regurgitation (TR) and improvements in functional class and quality of life (QOL). To analyze the impact of TTVI on maximal and submaximal exercise capacity (SEC). Constant work-rate exercise-time (CWRET) testing reflects SEC, which is more likely to be relevant for daily life activities and provides more differentiated physiological insight into the nature of exercise intolerance. Thus, 30 patients undergoing TTVI (21 direct annuloplasty and 9 edge-to-edge repair) received cardiopulmonary exercise testing (CPET) and CWRET (at 75% of maximum work rate in the initial CPET) before and 3months after TTVI. Patients' age was 80.5 [74.8-82.3] years and 53.3% were female. TR reduction ≥ 2 grades was achieved in 93.3% (TR grade ≤ moderate in 83.3%). Echocardiography revealed improved right ventricular (RV) characteristics with decreased RV basal diameter (47.0mm [43.0-54.3] vs. 41.5mm [36.8-48.0]; p < 0.001) and decreased inferior caval vein diameter. CWRET testing showed a significantly improved SEC (246.5s [153.8-416.8] vs. 338.5s [238.8-611.8] p = 0.001). Maximum oxygen uptake showed a positive trend without statistically significant differences (9.9ml/min/kg [8.6-12.4] vs. 11.7ml/min/kg [9.7-13.3]; p = 0.31). In contrast to the six-minute-walking distance (6MWD), SEC correlated moderately with effective regurgitation orifice area reduction (r = 0.385; p = 0.036), increased cardiac output (r = 0.378; p = 0.039), and improved QOL (r = 387; p = 0.035). Improvements in exercise capacity after TTVI mainly occur in the submaximal rather than in the maximal exercise range and correlate with hemodynamic effects and QOL. This may have a methodological impact on assessment of exercise capacity in these patients.

Free-swimming bacteria transcriptionally respond to shear flow

Surface-attached cells can sense and respond to shear flow, but planktonic (free-swimming) cells are typically assumed to be oblivious to any flow that carries them. Here, we find that planktonic bacteria can transcriptionally respond to flow, inducing expression changes that are beneficial in flow. Specifically, we use microfluidic experiments and quantitative modeling to show that in the presence of flow, planktonic Pseudomonas aeruginosa induce shear rate-dependent genes that promote growth in low-oxygen environments. Untangling this mechanism revealed that in flow, motile P. aeruginosa spatially redistribute, leading to cell density changes that activate quorum sensing, which in turn enhances the oxygen uptake rate. In diffusion-limited environments, including those commonly encountered by bacteria, flow-induced cell density gradients also independently generate oxygen gradients that alter gene expression. Mutants deficient in this flow-responsive mechanism exhibit decreased fitness in flow, suggesting that this dynamic coupling of biological and mechanical processes can be physiologically significant.

Production and Characterization of Fine-Grained Multielement AlCoxCrFeNi (x = 1, 0.75, 0.5) Alloys for High-Temperature Applications.

In the present work, three different AlCoxCrFeNi (x = 1, 0.75, 0.5) alloys were produced through the mechanical milling of powders and spark plasma sintering. These alloys were characterized in terms of their microstructural, mechanical, and oxidation behaviors. Mechanical milling and spark plasma sintering were chosen to achieve a fine and homogeneous microstructure. Pore-free samples were produced by properly setting the sintering parameters. The unavoidable uptake of oxygen from the powders when exposed to air after milling was advantageously used as a source of oxides, which acted as reinforcing particles in the alloy. Oxidation behavior, studied through TGA tests, showed that decreasing the Co content promotes better oxidation protection due to the formation of a dense, compact Al2O3 layer. The alloy containing the lowest amount of Co is considered a good candidate for high-temperature structural applications.

Oxygen uptake rate analysis to evaluate the impact of hydrodynamic stress on the growth of the avian cell line DuckCelt®-T17

Scale-up of bioprocesses involving animal cell culture is hampered by the sensitivity of the cells to hydrodynamic stress, either from agitation or bubble bursting. Here, the hydrodynamic stress experienced by a recent cell line, the DuckCelt®-T17 avian cells, previously used for viral vaccine production, is investigated in shake flasks and in a 3 L bioreactor. Cell stress was assessed by monitoring the dissolved oxygen in the culture medium, which depends on Oxygen Transfer Rate (OTR) and Oxygen Uptake Rate (OUR) during cultivation. Classical parameters such as the maximum growth rate (µmax) and metabolite profiles were also determined. A dynamic model able to predict nutrient consumption, metabolic waste production, viable cell number and OUR was also developed and validated from the data measured in shake flasks. The experiments performed in the stirred tank bioreactor (STBR) show that OUR depended on both the cell growth phase and the stirring conditions. The oxygen consumption of the cells during the exponential growth phase (where there were no nutrient and O2 limitations) was significantly altered at average and maximum shear rates above 70 and 840 s−1, respectively, indicating highly shear-sensitive cells. OUR is a suitable tool to identify the hydrodynamic conditions for robust cell growth. The scale-up criteria to be favored for the DuckCelt®-T17 cell culture in STBRs would be the shear and/or the tip’s speed.

An alternate to accumulated oxygen deficit (AOD) for measuring anaerobic contribution: 'AOD_alt' is valid in normoxia and hypoxia.

The gold standard measure of anaerobic contribution is accumulated oxygen deficit (AOD). The purpose of this study was to investigate the validity of an alternate measure, AOD_alt. AOD_alt is the sum of the phosphocreatine and glycolytic contributions, which are estimated from post-exercise oxygen uptake and blood lactate concentration, respectively. In Study One, six women and three men performed 6-min bouts of heavy intensity cycle ergometer exercise, once in normoxia (FIO2 ~ 21%) and twice under hypoxic conditions (FIO2 ~ 15% and ~ 12%). In Study Two, four women and two men performed severe intensity tests to exhaustion, once in normoxia (~ 10min) and twice in hypoxia (FIO2 ~ 15% and ~ 10%). Physiological responses were measured during exercise and 7min of recovery. In 6min of heavy exercise, Study One, the alternate and criterion measures of anaerobic contribution (AOD_alt and AOD) were correlated, in normoxia and in hypoxia. In exhaustive severe exercise, Study Two, AOD_alt and AOD were correlated (r = 0.77) and similar, in normoxia and at FIO2 ~ 15%. However, AOD_alt and AOD values were neither correlated (r = 0.27) nor similar (57 ± 5mL·kg-1 vs 51 ± 7mL·kg-1) at FIO2 ~ 10%. These results confirm the validity of AOD_alt as a measure of anaerobic capacity in severe intensity exercise, demonstrate its validity in heavy exercise, and assert its validity in conditions of hypoxia (FIO2 ~ 12%).

8731 Glucose homeostasis remains normal across a range of adiposity in fit men and women

Abstract Disclosure: A.W. Potter: None. G.C. Chin: None. J.I. Jacques: None. L.J. Nindl: None. D.P. Looney: None. W.J. Tharion: None. C.L. Chapman: None. E.N. Halford: None. K.E. Friedl: None. Introduction. Glucose dysregulation is a major obesity-related comorbidity, affecting mental and physical performance. Glycated hemoglobin (HbA1c) is a validated and stable biomarker representing glucose regulation over 2-3 months. Nearly half of American adults (41%) have elevated HbA1c concentrations representing prediabetes (≥5.7%). In a large cross-sectional sampling of the American population, HbA1c becomes elevated in 33% of individuals at &amp;gt;24% body fat (BF) (men) and &amp;gt;38%BF (women). However, daily physical activity is an important moderator of metabolic health and adiposity - the “fit fat” concept. We evaluated this effect in physically active men and women. Methods. Body composition and metabolic health data were obtained from 36,392 adults (18,130 men and 18,262 women) in the National Health and Nutrition Examination Survey (NHANES) from 1999-2018, for comparison of %BF and HbA1c relationships. Body composition and HbA1c data were obtained from 220 healthy and physically fit active-duty military men and women (188 men, mean ± SD (range): age 25.7 ± 5.9 (18-53) years; height 176.3 ± 7.7 (154.0-201.1) cm; body mass 85.3 ± 11.9 (55.7-134.7) kg, maximal oxygen uptake (VO2max) 49.1 ± 11.9 (33.8-62.5) ml/kg/min; 32 women, age 26.5 ± 7.0 (19-45) years; height 161.4 ± 5.9 (147.1-172.8) cm; body mass 63.9 ± 8.3 (46.7-86.6) kg, VO2max 42.5 ± 8.3 (29.1-52.6) ml/kg/min). Body composition was measured using DXA (iDXA, General Electric Healthcare, Madison, WI) and HbA1c was measured from capillary blood samples using a validated point-of-care analyzer (DCA Vantage Analyzer, Siemens Medical Solutions USA, Inc, Malvern, PA). Results. HbA1c remained within the normal range (&amp;lt;5.7%) for 98% (216/220) of a relatively wide range of %BF in a group of men (9-36%) and women (21-46%) who engaged in daily physical activity. This sample included 64 men (34%) and 4 women (12.5%) that exceeded the 24 and 38%BF thresholds where clinically high HbA1c concentrations have been observed in the civilian population. From this subset, none of the assessed women had HbA1c ≥5.7%. Three men had HbA1c 5.7-5.8% and also high measured physical fitness (VO2max, 50.1-62.5 ml/kg/min) and low %BF (15-17%); while one had lower physical fitness (VO2max 43.87 ml/kg/min) and higher body fat (26%) (HbA1c 6%). Conclusion. Glucose homeostasis remains within normal values across a range of adiposity in fit men and women. These data support the importance of daily physical activity in mitigating elevations in HbA1c, even in individuals with increased relative body fat. Physical activity appears to have a protective effect for metabolism. Presentation: 6/3/2024

Modification of SMWT for remote heart’s functional capacity determination from oxygen consumption rate

Cardiovascular disease (CVD) is series of diseases affects blood circulation and heart which are fatal to human being. CVD patients recorded that every each of them must have at least one among the following behavioural risks: smoking, diabetes, obesity, hypertension, high cholesterol, and sedentary lifestyle. The diagnosis for CVD is commonly through cardiac stress test. It is a test where electrocardiogram will be used to monitor heart activity under induced stress such as walking on treadmill. However, the facilities for the cardiac stress test are very limited and increasing number of patients with potential CVD caused a long queue for an appointment. This situation makes it hard for healthy people living with behavioral risk wanting for their heart to be checked. Therefore, in this paper, we proposed to determine heart functional capacity which can be done anywhere and sufficient to access heart condition. For this proposal, despite using treadmill-test, Six-Minutes Walking Test (SMWT) is utilized. SMWT induces stress while the heart’s endurance parameters such as heart rate is extracted. This study developed an integrated sensor device which comprises of a sensor to detect step count calculate distance, and a pulse sensor that detect heart rate. Then, oxygen consumption rate during the SMWT, is computed. Metabolic equivalent of task (MET) is equal to the oxygen consumption rate during activity over resting oxygen consumption rate. Heart functional capacity classification is about exercise intensity and the MET of SMWT can be compared to the classification which allows this paper to determine heart functional capacity remotely using SMWT. Based on the results, the heart’s functional capacity classification after performing SMWT using sensor device is Class 1, the same when using manual calculation for distance and heart rate. The device sensor somehow produce error at 20.63% when calculating oxygen uptake. Nevertheless, this paper is identified that the SMWT is able to classify the heart’s functional capacity.