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Arquivos Brasileiros de Cardiologia Dec 2023Central Illustration : Prediction of Peak Oxygen Consumption in Patients with Heart Disease Based on Performance on the Timed Up and Go Test CPET: cardiopulmonary...
BACKGROUND
Central Illustration : Prediction of Peak Oxygen Consumption in Patients with Heart Disease Based on Performance on the Timed Up and Go Test CPET: cardiopulmonary exercise test; TUG: timed up and go test; VO2peak: peak oxygen consumption.
BACKGROUND
The use of the timed up and go (TUG) test to assess cardiorespiratory fitness in patients with heart disease has not been well defined in the literature.
OBJECTIVES
Test the association between TUG and peak oxygen consumption (VO2peak), construct an equation based on TUG to predict VO2peak, and determine a cutoff point to estimate VO2peak ≥ 20 mL/kg/min.
METHODS
This cross-sectional study included 201 patients with coronary artery disease or heart failure, between 36 and 92 years of age, who underwent TUG and cardiopulmonary exercise test. Correlation, ROC curve, multiple linear regression, and Bland-Altman analyses were performed. The significance level was set at p < 0.05.
RESULTS
The mean age of the total sample was 67 ± 13 years, and 70% of participants were male. The mean VO2peak was 17 ± 6 mL/kg/min, and the mean TUG time was 7 ± 2.5 seconds. The correlation between VO2peak and TUG was r = -0.54 (p < 0.001), and R2 was 0.30. The following equation was developed based on TUG: V O 2 peak = 33.553 + ( - 0.149 × age ) + ( - 0.738 × TUG ) + ( - 2.870 × sex ) ; a value of 0 was assigned to the male sex and 1 to the female sex (adjusted R: 0.41; adjusted R2: 0.40). The VO2peak estimated by the equation was 18.81 ± 3.2 mL/kg/min, and the VO2peak determined by cardiopulmonary exercise test was 18.18 ± 5.9 mL/kg/min (p > 0.05). The best cutoff point in the TUG for VO2peak ≥ 20 mL/kg/min was ≤ 5.47 seconds (area under the curve: 0.80; 95% confidence interval: 0.74 to 0.86).
CONCLUSIONS
TUG and VO2peak showed a significant association. A prediction equation for VO2peak was developed and validated internally with good performance. The cutoff point in the TUG to predict VO2peak ≥ 20 mL/kg/min was ≤ 5.47 seconds.
Topics: Humans; Male; Female; Middle Aged; Aged; Aged, 80 and over; Cross-Sectional Studies; Postural Balance; Time and Motion Studies; Exercise Test; Heart Failure; Oxygen Consumption
PubMed: 38126569
DOI: 10.36660/abc.20230338 -
Methods in Molecular Biology (Clifton,... 2024An analysis of the mitochondrial respiration function represented by the oxygen consumption rate is necessary to assess mitochondrial bioenergetics and redox function....
An analysis of the mitochondrial respiration function represented by the oxygen consumption rate is necessary to assess mitochondrial bioenergetics and redox function. This protocol describes two alternative techniques to evaluate mitochondrial respiration function in situ: (1) measure oxygen consumption rates via an electrode; (2) measure oxygen consumption rates via a seahorse instrument. These in situ approaches provide more physiological access to mitochondria to evaluate mitochondrial respiration function in a relatively integrated cellular system.
Topics: Oxygen Consumption; Respiration; Mitochondria; Electrodes; Respiratory Function Tests
PubMed: 38319581
DOI: 10.1007/978-1-0716-3633-6_16 -
International Journal of Sports... Nov 2023The aim of this study was to describe individual training characteristics, racing strategies, and periodization in preparation for the Tour de France in 2 world-class...
PURPOSE
The aim of this study was to describe individual training characteristics, racing strategies, and periodization in preparation for the Tour de France in 2 world-class road cyclists finishing in the top 5 of the general classification.
METHODS
Week-by-week power meter training and racing data of 2 (A and B) road cyclists (age: 29 and 23 y; maximum oxygen consumption: 83 and 81 mL·min-1·kg-1; and relative 20-min record power output: 6.9 and 6.5 W·kg-1) in the preparation phase (December-July/August) leading up to the Tour de France were retrospectively analyzed. Weekly volume and intensity distribution in power zones were considered.
RESULTS
Cyclists A and B completed 46 and 19 races, 22.5 (6.3) and 18.2 (5.1) h·wk-1, with a pyramidal intensity distribution of 81.0%-13.3%-5.7%, and 88.8%-7.9%-3.3% in zone 1-zone 2-zone 3. Cyclist B spent 14 days at altitude. Increased high-intensity volume and polarization index occurred during race weeks. During periods without racing, training intensity progressively increased. Strength training was performed during November and December but not during the following months. During tapering, total exercise volume and time at high intensity decreased.
CONCLUSION
These data provide novel insights into the periodization of world-class road cyclists in advance of a top 5 placing in the Tour de France general classification.
Topics: Humans; Physical Endurance; Retrospective Studies; Bicycling; Competitive Behavior; Oxygen Consumption; France
PubMed: 37709277
DOI: 10.1123/ijspp.2023-0142 -
Marine Environmental Research Oct 2023Pest management strategies to reduce sea lice infestations in the salmon aquaculture industry include in-feed treatments with ivermectin (IVM) and SLICE® (active...
Pest management strategies to reduce sea lice infestations in the salmon aquaculture industry include in-feed treatments with ivermectin (IVM) and SLICE® (active ingredient [AI] emamectin benzoate [EMB]), which can result in local contamination of the environment. These compounds partition to sediments, have moderate persistence, and may pose a risk to non-target benthic organisms. The sub-lethal effects of EMB, IVM and a combination of both (EMB/IVM) on the benthic amphipod Eohaustorius estuarius and polychaete Nereis virens at environmentally relevant sediment concentrations were examined in subchronic exposures (28-30-d). E. estuarius avoided sediment containing >50 μg/kg IVM alone and in combination with EMB. N. virens avoided sediment with >50 μg/kg IVM and >0.5 μg/kg EMB/IVM and exhibited impaired burrowing and locomotory behaviour with both treatments. Oxygen consumption was significantly decreased in E. estuarius (up to 50% compared to controls) and increased in N. virens (by ∼ 200%) when exposed to EMB, IVM and EMB/IVM at concentrations <5 μg/kg. IVM, SLICE® and combination exposures at environmentally relevant concentrations caused adverse effects in E. estuarius and N. virens which could significantly alter organism fitness near salmon aquaculture operations.
Topics: Animals; Ivermectin; Antiparasitic Agents; Avoidance Learning; Aquatic Organisms; Oxygen Consumption; Invertebrates; Geologic Sediments; Water Pollutants, Chemical
PubMed: 37690394
DOI: 10.1016/j.marenvres.2023.106155 -
American Journal of Physiology.... Dec 2023Exercise is associated with the development of oxidative stress, but the specific source and mechanism of production of pro-oxidant chemicals during exercise has not...
Exercise is associated with the development of oxidative stress, but the specific source and mechanism of production of pro-oxidant chemicals during exercise has not been confirmed. We used equine skeletal muscle mitochondria to test the hypothesis that hyperthermia and acidosis affect mitochondrial oxygen consumption and production of reactive oxygen species (ROS). Skeletal muscle biopsies were obtained at rest, after an acute episode of fatiguing exercise, and after a 9-wk conditioning program to increase aerobic fitness. Mitochondrial oxygen consumption and ROS production were measured simultaneously using high-resolution respirometry. Both hyperthermia and acidosis increased nonphosphorylating (LEAK) respiration (5.8× and 3.0×, respectively, < 0.001) and decreased efficiency of oxidative phosphorylation. The combined effects of hyperthermia and acidosis resulted in large decreases in phosphorylating respiration, further decreasing oxidative phosphorylation efficiency from 97% to 86% ( < 0.01). Increased aerobic fitness reduced the effects of acidosis on LEAK respiration. Hyperthermia increased and acidosis decreased ROS production (2× and 0.23×, respectively, < 0.001). There was no effect of acute exercise, but an aerobic conditioning program was associated with increased ROS production during both nonphosphorylating and phosphorylating respiration. Hyperthermia increased the ratio of ROS production to O consumption during phosphorylating respiration, suggesting that high-temperature impaired transfer of energy through the electron transfer system despite relatively low mitochondrial membrane potential. These data support the role of skeletal muscle mitochondria in the development of exercise-induced oxidative stress, particularly during forms of exercise that result in prolonged hyperthermia without acidosis. The results of this study provide evidence for the role of mitochondria-derived ROS in the development of systemic oxidative stress during exercise as well as skeletal muscle diseases such as exertional rhabdomyolysis.
Topics: Animals; Horses; Reactive Oxygen Species; Mitochondria; Mitochondria, Muscle; Muscle, Skeletal; Acidosis; Oxygen Consumption; Hyperthermia; Hyperthermia, Induced
PubMed: 37811714
DOI: 10.1152/ajpregu.00177.2023 -
Eye (London, England) Aug 2023Clinical methods examining oxygenation parameters in humans have been used in many different care settings, but concerns have been raised regarding their clinical...
BACKGROUND
Clinical methods examining oxygenation parameters in humans have been used in many different care settings, but concerns have been raised regarding their clinical utility when assessing people with darker skin pigmentation. While saturation values can be crucial in emergency medicine, they are equally valuable in assessing disease mechanisms and monitoring change in disease progression. Retinal pigmentation varies across individuals and hence, can impact on retinal oxygen parameters. The objective of this study was to quantify and eliminate the impact of retinal pigmentation on retinal vessel oxygen saturation parameters measured in the superficial retinal arterioles and venules.
METHODS
105 healthy individuals of varying skin colour, iris colour and heritage were included. Following a full eye exam to exclude any ocular abnormality, all participants underwent intraocular pressure, systemic blood pressure measurements and dilated dual wavelength retinal photography. Rotation matrices were employed to minimise the dependency of retinal pigmentation on arterial and venous oxygen saturation measurements determined in a concentric measurement annulus.
RESULTS
Retinal oxygen saturation in venules showed a linear correlation with retinal pigmentation (y = 0.34 × x + 38.598), whereas arterial saturation followed a polynomial pattern (y = 0.0089 × x + 0.7499 × x + 85.073). Both arterial and venous saturation values were corrected using local fundus pigmentation. Pre-correction retinal arterial and venous oxygen saturation were 89.0% (±13.1) and 43.7% (±11.5), respectively, and post- correction values were 94.8% (±8.7) for arteries and 56.3% (±7.0) veins.
CONCLUSIONS
When assessing multi-ethnic cohorts, it is important to consider the impact of pigmentation on imaging parameters and to account for it prior to clinical interpretation.
Topics: Humans; Oximetry; Retinal Vessels; Oxygen; Retina; Fundus Oculi; Oxygen Consumption
PubMed: 36460856
DOI: 10.1038/s41433-022-02325-7 -
Scientific Reports Sep 2023Some of the prominent features of long-term memory formation include protein synthesis, gene expression, enhanced neurotransmitter release, increased excitability, and...
Some of the prominent features of long-term memory formation include protein synthesis, gene expression, enhanced neurotransmitter release, increased excitability, and formation of new synapses. As these processes are critically dependent on mitochondrial function, we hypothesized that increased mitochondrial respiration and dynamics would play a prominent role in memory formation. To address this possibility, we measured mitochondrial oxygen consumption (OCR) in hippocampal tissue punches from trained and untrained animals. Our results show that context fear training significantly increased basal, ATP synthesis-linked, and maximal OCR in the Shaffer collateral-CA1 synaptic region, but not in the CA1 cell body layer. These changes were recapitulated in synaptosomes isolated from the hippocampi of fear-trained animals. As dynamin-related protein 1 (Drp1) plays an important role in mitochondrial fission, we examined its role in the increased mitochondrial respiration observed after fear training. Drp1 inhibitors decreased the training-associated enhancement of OCR and impaired contextual fear memory, but did not alter the number of synaptosomes containing mitochondria. Taken together, our results show context fear training increases presynaptic mitochondria respiration, and that Drp-1 mediated enhanced energy production in CA1 pre-synaptic terminals is necessary for context fear memory that does not result from an increase in the number of synaptosomes containing mitochondria or an increase in mitochondrial mass within the synaptic layer.
Topics: Animals; Biological Transport; Oxygen Consumption; Synapses; Memory Disorders; Mitochondria
PubMed: 37660191
DOI: 10.1038/s41598-023-40877-0 -
Physiological Genomics Aug 2023Maximal aerobic exercise capacity [maximal oxygen consumption (V̇o)] is one of the strongest predictors of morbidity and mortality. Aerobic exercise training can... (Randomized Controlled Trial)
Randomized Controlled Trial
Maximal aerobic exercise capacity [maximal oxygen consumption (V̇o)] is one of the strongest predictors of morbidity and mortality. Aerobic exercise training can increase V̇o, but inter-individual variability is marked and unexplained physiologically. The mechanisms underlying this variability have major clinical implications for extending human healthspan. Here, we report a novel transcriptome signature related to ΔV̇o with exercise training detected in whole blood RNA. We used RNA-Seq to characterize transcriptomic signatures of ΔV̇o in healthy women who completed a 16-wk randomized controlled trial comparing supervised, higher versus lower aerobic exercise training volume and intensity (4 training groups, fully crossed). We found significant baseline gene expression differences in subjects who responded to aerobic exercise training with robust versus little/no ΔV̇o, and differentially expressed genes/transcripts were mostly related to inflammatory signaling and mitochondrial function/protein translation. Baseline gene expression signatures associated with robust versus little/no ΔV̇o were also modulated by exercise training in a dose-dependent manner, and they predicted ΔV̇o in this and a separate dataset. Collectively, our data demonstrate the potential utility of using whole blood transcriptomics to study the biology of inter-individual variability in responsiveness to the same exercise training stimulus.
Topics: Humans; Female; Transcriptome; Exercise; Exercise Tolerance; Endurance Training; Oxygen Consumption
PubMed: 37335021
DOI: 10.1152/physiolgenomics.00017.2023 -
Sensors (Basel, Switzerland) Nov 2023New and promising variables are being developed to analyze performance and fatigue in trail running, such as mechanical power, metabolic power, metabolic cost of...
New and promising variables are being developed to analyze performance and fatigue in trail running, such as mechanical power, metabolic power, metabolic cost of transport and mechanical efficiency. The aim of this study was to analyze the behavior of these variables during a real vertical kilometer field test. Fifteen trained trail runners, eleven men (from 22 to 38 years old) and four women (from 19 to 35 years old) performed a vertical kilometer with a length of 4.64 km and 835 m positive slope. During the entire race, the runners were equipped with portable gas analyzers (Cosmed K5) to assess their cardiorespiratory and metabolic responses breath by breath. Significant differences were found between top-level runners versus low-level runners in the mean values of the variables of mechanical power, metabolic power and velocity. A repeated-measures ANOVA showed significant differences between the sections, the incline and the interactions between all the analyzed variables, in addition to differences depending on the level of the runner. The variable of mechanical power can be statistically significantly predicted from metabolic power and vertical net metabolic COT. An algebraic expression was obtained to calculate the value of metabolic power. Integrating the variables of mechanical power, vertical velocity and metabolic power into phone apps and smartwatches is a new opportunity to improve performance monitoring in trail running.
Topics: Male; Humans; Female; Young Adult; Adult; Oxygen Consumption; Running; Energy Metabolism; Fatigue; Biomechanical Phenomena
PubMed: 38067721
DOI: 10.3390/s23239349 -
The Journal of Physiology Dec 2023Late gestational supine positioning reduces maternal cardiac output due to inferior vena caval (IVC) compression, despite increased collateral venous return. However,...
Late gestational supine positioning reduces maternal cardiac output due to inferior vena caval (IVC) compression, despite increased collateral venous return. However, little is known about the impact of maternal position on oxygen (O ) delivery and consumption of the gravid uterus, fetus, placenta and lower limbs. We studied the effects of maternal positioning on these parameters in 20 healthy pregnant subjects at 36 ± 2 weeks using magnetic resonance imaging (MRI); a follow-up MRI was performed 6-months postpartum (n = 16/20). MRI techniques included phase-contrast and T1/T2 relaxometry for blood flow and oximetry imaging, respectively. O transport was measured in the following vessels (bilateral where appropriate): maternal abdominal descending aorta (DAo ), IVC, ovarian, paraspinal veins (PSV), uterine artery (UtA) and external iliacs, and umbilical. Maternal cardiac output was measured by summing DAo and superior vena cava flows. Supine mothers (n = 6) had lower cardiac output and O delivery in the DAo , UtA and external iliac arteries, and higher PSV flow than those in either the left (n = 8) or right (n = 6) lateral positions during MRI. However, O consumption in the gravid uterus, fetus, placenta and lower limbs was unaffected by maternal positioning. The ratio of IVC/PSV flow decreased in supine mothers while ovarian venous flow and O saturation were unaltered, suggesting a major route of pelvic venous return unaffected by maternal position. Placental-fetal O transport and consumption were similar between left and right lateral maternal positions. In comparison to non-pregnant findings, DAo and UtA O delivery and pelvic O consumption increased, while lower-limb consumption remained constant , despite reduced external iliac artery O delivery in late gestation. KEY POINTS: Though sleeping supine during the third trimester is associated with an increased risk of antepartum stillbirth, the underlying biological mechanisms are not fully understood. Maternal cardiac output and uteroplacental flow are reduced in supine mothers due to inferior vena caval compression from the weight of the gravid uterus. This MRI study provides a comprehensive circulatory assessment, demonstrating reduced maternal cardiac output and O delivery (uteroplacental, lower body) in supine compared to lateral positioning; however, O consumption (gravid uterus, fetus, placenta, lower limbs) was preserved. Unlike other mammalian species, the ovarian veins conduct substantial venous return from the human pregnant uterus that is unaffected by maternal positioning. Lumbar paraspinal venous flow increased in supine mothers. These observations may have important considerations during major pelvic surgery in pregnancy (i.e. placenta percreta). Future studies should address the importance of maternal positioning as a potential tool to deliver improved perinatal outcomes in pregnancies with compromised uteroplacental O delivery.
Topics: Female; Humans; Pregnancy; Feasibility Studies; Fetus; Magnetic Resonance Imaging; Oxygen; Oxygen Consumption; Placenta; Vena Cava, Superior
PubMed: 37906114
DOI: 10.1113/JP285097