scholarly journals Effects of Short-Term Phosphate Loading on Aerobic Capacity under Acute Hypoxia in Cyclists: A Randomized, Placebo-Controlled, Crossover Study

Nutrients ◽  
2022 ◽  
Vol 14 (2) ◽  
pp. 236
Author(s):  
Kamila Płoszczyca ◽  
Małgorzata Chalimoniuk ◽  
Iwona Przybylska ◽  
Miłosz Czuba
Keyword(s):  
Crossover Study ◽  
Aerobic Capacity ◽  
Acute Hypoxia ◽  
Hypoxia Inducible Factor ◽  
Oxygen Affinity ◽  
Individual Variability ◽  
Aerobic Performance ◽  
Acid Base Balance ◽  
Phosphate Loading ◽  
2,3 Dpg

The aim of this study was to evaluate the effects of sodium phosphate (SP) supplementation on aerobic capacity in hypoxia. Twenty-four trained male cyclists received SP (50 mg·kg−1 of FFM/day) or placebo for six days in a randomized, crossover study, with a three-week washout period between supplementation phases. Before and after each supplementation phase, the subjects performed an incremental exercise test to exhaustion in hypoxia (FiO2 = 16%). Additionally, the levels of 2,3-diphosphoglycerate (2,3-DPG), hypoxia-inducible factor 1 alpha (HIF-1α), inorganic phosphate (Pi), calcium (Ca), parathyroid hormone (PTH) and acid-base balance were determined. The results showed that phosphate loading significantly increased the Pi level by 9.0%, whereas 2,3-DPG levels, hemoglobin oxygen affinity, buffering capacity and myocardial efficiency remained unchanged. The aerobic capacity in hypoxia was not improved following SP. Additionally, our data revealed high inter-individual variability in response to SP. Therefore, the participants were grouped as Responders and Non-Responders. In the Responders, a significant increase in aerobic performance in the range of 3–5% was observed. In conclusion, SP supplementation is not an ergogenic aid for aerobic capacity in hypoxia. However, in certain individuals, some benefits can be expected, but mainly in athletes with less training-induced central and/or peripheral adaptation.

scholarly journals Is a Four-Week Ketogenic Diet an Effective Nutritional Strategy in CrossFit-Trained Female and Male Athletes?

Nutrients ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 864 ◽  
Author(s):  
Krzysztof Durkalec-Michalski ◽  
Paulina M. Nowaczyk ◽  
Natalia Główka ◽  
Anna Ziobrowska ◽  
Tomasz Podgórski
Keyword(s):  
Ketogenic Diet ◽  
Aerobic Capacity ◽  
Alanine Aminotransferase ◽  
Aerobic Performance ◽  
Entire Group ◽  
Acid Base Balance ◽  
Acid Base ◽  
Relevant Effect ◽  
Increased Risk ◽  
Specific Performance

This single-arm interventional study examined the effect of a 4-week ketogenic diet (KD) on aerobic capacity and discipline-specific performance in female (n = 11) and male (n = 11) CrossFit-trained athletes. The participants performed incremental cycling (ICT) and Fight Gone Bad (FGB) tests after consuming a customary diet and a KD. Pre- and post-ICT exercise blood samples were also analysed. Consuming a KD had a slight impact on aerobic capacity and no relevant effect on CrossFit-specific performance. In females, consuming a KD led to an 10.4% decrease in peak oxygen uptake during the ICT (p = 0.027) and resulted in certain alterations in haematological parameters (haemoglobin (HGB), mean corpuscular HGB, and mean corpuscular HGB concentration). Furthermore, in males, alanine aminotransferase activity increased with a simultaneous improvement in the post-ICT blood acid–base balance after consuming a KD. The pre-exercise bilirubin concentration was also elevated in the entire group after consuming a KD. In conclusion, female CrossFit-trained athletes seem to be prone to aerobic performance decrements and increased risk of developing haematological disturbances when consuming a KD. In males who consumed a KD, there was an undesirable alanine aminotransferase elevation and a small tendency towards improved acid–base status. Moreover, consuming a KD had no effect on discipline-specific performance in CrossFit-trained athletes.

scholarly journals Hypoxia Performance Curve: Assess a Whole-Organism Metabolic Shift from a Maximum Aerobic Capacity towards a Glycolytic Capacity in Fish

Metabolites ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 447
Author(s):  
Yangfan Zhang ◽  
Bog E. So ◽  
Anthony P. Farrell
Keyword(s):  
Metabolic Rate ◽  
Aerobic Capacity ◽  
Metabolic Response ◽  
Anaerobic Capacity ◽  
Standard Metabolic Rate ◽  
Individual Variability ◽  
Aerobic Performance ◽  
Performance Curve ◽  
Individual Fish ◽  
O2 Supply

The utility of measuring whole-animal performance to frame the metabolic response to environmental hypoxia is well established. Progressively reducing ambient oxygen (O2) will initially limit maximum metabolic rate as a result of a hypoxemic state and ultimately lead to a time-limited, tolerance state supported by substrate-level phosphorylation when the O2 supply can no longer meet basic needs (standard metabolic rate, SMR). The metabolic consequences of declining ambient O2 were conceptually framed for fishes initially by Fry’s hypoxic performance curve, which characterizes the hypoxemic state and its consequences to absolute aerobic scope (AAS), and Hochachka’s concept of scope for hypoxic survival, which characterizes time-limited life when SMR cannot be supported by O2 supply. Yet, despite these two conceptual frameworks, the toolbox to assess whole-animal metabolic performance remains rather limited. Here, we briefly review the ongoing debate concerning the need to standardize the most commonly used assessments of respiratory performance in hypoxic fishes, namely critical O2 (the ambient O2 level below which maintenance metabolism cannot be sustained) and the incipient lethal O2 (the ambient O2 level at which a fish loses the ability to maintain upright equilibrium), and then we advance the idea that the most useful addition to the toolbox will be the limiting-O2 concentration (LOC) performance curve. Using Fry & Hart’s (1948) hypoxia performance curve concept, an LOC curve was subsequently developed as an eco-physiological framework by Neil et al. and derived for a group of fish during a progressive hypoxia trial by Claireaux and Lagardère (1999). In the present review, we show how only minor modifications to available respirometry tools and techniques are needed to generate an LOC curve for individual fish. This individual approach to the LOC curve determination then increases its statistical robustness and importantly opens up the possibility of examining individual variability. Moreover, if peak aerobic performance at a given ambient O2 level of each individual is expressed as a percentage of its AAS, the water dissolved O2 that supports 50% of the individual’s AAS (DOAAS-50) can be interpolated much like the P50 for an O2 hemoglobin dissociation curve (when hemoglobin is 50% saturated with O2). Thus, critical O2, incipient lethal O2, DOAAS-50 and P50 and can be directly compared within and across species. While an LOC curve for individual fish represents a start to an ongoing need to seamlessly integrate aerobic to anaerobic capacity assessments in a single, multiplexed respirometry trial, we close with a comparative exploration of some of the known whole-organism anaerobic and aerobic capacity traits to examine for correlations among them and guide the next steps.

scholarly journals The Effect of Eight-Week Sprint Interval Training on Aerobic Performance of Elite Badminton Players

2021 ◽  
Vol 18 (2) ◽  
pp. 638
Author(s):  
Haochong Liu ◽  
Bo Leng ◽  
Qian Li ◽  
Ye Liu ◽  
Dapeng Bao ◽  
...  
Keyword(s):  
Oxygen Uptake ◽  
Anaerobic Threshold ◽  
Aerobic Capacity ◽  
Interval Training ◽  
Lactate Clearance ◽  
Aerobic Performance ◽  
Sprint Interval Training ◽  
Control Groups ◽  
Ventilatory Anaerobic Threshold ◽  
And Control

This study was aimed to: (1) investigate the effects of physiological functions of sprint interval training (SIT) on the aerobic capacity of elite badminton players; and (2) explore the potential mechanisms of oxygen uptake, transport and recovery within the process. Thirty-two elite badminton players volunteered to participate and were randomly divided into experimental (Male-SIT and Female-SIT group) and control groups (Male-CON and Female-CON) within each gender. During a total of eight weeks, SIT group performed three times of SIT training per week, including two power bike trainings and one multi-ball training, while the CON group undertook two Fartlek runs and one regular multi-ball training. The distance of YO-YO IR2 test (which evaluates player’s ability to recover between high intensity intermittent exercises) for Male-SIT and Female-SIT groups increased from 1083.0 ± 205.8 m to 1217.5 ± 190.5 m, and from 725 ± 132.9 m to 840 ± 126.5 m (p < 0.05), respectively, which were significantly higher than both CON groups (p < 0.05). For the Male-SIT group, the ventilatory anaerobic threshold and ventilatory anaerobic threshold in percentage of VO2max significantly increased from 3088.4 ± 450.9 mL/min to 3665.3 ± 263.5 mL/min (p < 0.05),and from 74 ± 10% to 85 ± 3% (p < 0.05) after the intervention, and the increases were significantly higher than the Male-CON group (p < 0.05); for the Female-SIT group, the ventilatory anaerobic threshold and ventilatory anaerobic threshold in percentage of VO2max were significantly elevated from 1940.1 ± 112.8 mL/min to 2176.9 ± 78.6 mL/min, and from 75 ± 4% to 82 ± 4% (p < 0.05) after the intervention, which also were significantly higher than those of the Female-CON group (p < 0.05). Finally, the lactate clearance rate was raised from 13 ± 3% to 21 ± 4% (p < 0.05) and from 21 ± 5% to 27 ± 4% for both Male-SIT and Female-SIT groups when compared to the pre-test, and this increase was significantly higher than the control groups (p < 0.05). As a training method, SIT could substantially improve maximum aerobic capacity and aerobic recovery ability by improving the oxygen uptake and delivery, thus enhancing their rapid repeated sprinting ability.

scholarly journals Association of EGLN1 gene with high aerobic capacity of Peruvian Quechua at high altitude

2019 ◽  
Vol 116 (48) ◽  
pp. 24006-24011 ◽  
Author(s):  
Tom D. Brutsaert ◽  
Melisa Kiyamu ◽  
Gianpietro Elias Revollendo ◽  
Jenna L. Isherwood ◽  
Frank S. Lee ◽  
...  
Keyword(s):  
Natural Selection ◽  
Aerobic Capacity ◽  
Cellular Response ◽  
Hypoxia Inducible Factor ◽  
Total Sample ◽  
Causal Variant ◽  
Analysis Of Covariance ◽  
Adaptation To Hypoxia ◽  
Spurious Association ◽  
Factor Α

Highland native Andeans have resided at altitude for millennia. They display high aerobic capacity (VO2max) at altitude, which may be a reflection of genetic adaptation to hypoxia. Previous genomewide (GW) scans for natural selection have nominated Egl-9 homolog 1 gene (EGLN1) as a candidate gene. The encoded protein, EGLN1/PHD2, is an O2 sensor that controls levels of the Hypoxia Inducible Factor-α (HIF-α), which regulates the cellular response to hypoxia. From GW association and analysis of covariance performed on a total sample of 429 Peruvian Quechua and 94 US lowland referents, we identified 5 EGLN1 SNPs associated with higher VO2max (L⋅min−1 and mL⋅min−1⋅kg−1) in hypoxia (rs1769793, rs2064766, rs2437150, rs2491403, rs479200). For 4 of these SNPs, Quechua had the highest frequency of the advantageous (high VO2max) allele compared with 25 diverse lowland comparison populations from the 1000 Genomes Project. Genotype effects were substantial, with high versus low VO2max genotype categories differing by ∼11% (e.g., for rs1769793 SNP genotype TT = 34.2 mL⋅min−1⋅kg−1 vs. CC = 30.5 mL⋅min−1⋅kg−1). To guard against spurious association, we controlled for population stratification. Findings were replicated for EGLN1 SNP rs1769793 in an independent Andean sample collected in 2002. These findings contextualize previous reports of natural selection at EGLN1 in Andeans, and support the hypothesis that natural selection has increased the frequency of an EGLN1 causal variant that enhances O2 delivery or use during exercise at altitude in Peruvian Quechua.

scholarly journals A possible role for hypoxia-induced apelin expression in enteric cell proliferation

2008 ◽  
Vol 294 (6) ◽  
pp. R1832-R1839 ◽  
Author(s):  
Song Han ◽  
Guiyun Wang ◽  
Xiang Qi ◽  
Heung M. Lee ◽  
Ella W. Englander ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Epithelial Cell ◽  
Intestinal Inflammation ◽  
Acute Hypoxia ◽  
Hypoxia Inducible Factor ◽  
Mrna Levels ◽  
Epithelial Cell Proliferation ◽  
Gi Tract ◽  
Rat Pups

Apelin is the endogenous ligand for the APJ receptor, and apelin and APJ are expressed in the gastrointestinal (GI) tract. Intestinal inflammation increases intestinal hypoxia-inducible factor (HIF) and apelin expression. Hypoxia and inflammation are closely linked cellular insults. The purpose of these studies was to investigate the influence of hypoxia on enteric apelin expression. Exposure of rat pups to acute hypoxia increased hepatic, stomach-duodenal, and colonic apelin mRNA levels 10-, 2-, and 2-fold, respectively ( P < 0.05 vs. controls). Hypoxia also increased colonic APJ mRNA levels, and apelin treatment during hypoxia exposure enhanced colonic APJ mRNA levels further. In vitro hypoxia also increased apelin and APJ mRNA levels. The hypoxia-induced elevation in apelin expression is most likely mediated by HIF, since HIF-activated apelin transcriptional activity is dependent on an intact, putative HIF binding site in the rat apelin promoter. Acute exposure of rat pups to hypoxia lowered gastric and colonic epithelial cell proliferation; hypoxia in combination with apelin treatment increased epithelial proliferation by 50%. In vitro apelin treatment of enteric cells exposed to hypoxia increased cell proliferation. Apelin treatment during normoxia was ineffective. Our studies imply that the elevation in apelin expression during hypoxia and inflammation in the GI tract functions in part to stimulate epithelial cell proliferation.

scholarly journals Adult and fetal haemoglobin J-Sardegna [α50(CE8)His→Asp]: functional and molecular modelling studies

2000 ◽  
Vol 346 (1) ◽  
pp. 193-199 ◽  
Author(s):  
Marcella CORDA ◽  
Maria C. DE ROSA ◽  
Maria G. PELLEGRINI ◽  
Maria T. SANNA ◽  
Alessandra OLIANAS ◽  
...  
Keyword(s):  
Functional Properties ◽  
Computational Modelling ◽  
Oxygen Affinity ◽  
Oxygen Binding ◽  
Structural Level ◽  
Fetal Haemoglobin ◽  
Significant Difference ◽  
Molecular Modelling Studies ◽  
Modelling Studies ◽  
2,3 Dpg

Haemoglobin (Hb) J-Sardegna [α50(CE8)His → Asp] is a haemoglobin variant characteristic of subjects from the island of Sardinia. Here we report a study of the functional properties of both fetal and adult Hb J-Sardegna. The results indicate that adult Hb J-Sardegna displays an oxygen affinity that is higher than that of adult Hb only in the presence of 2,3-diphosphoglycerate (2,3-DPG). On the contrary, at 20 °C, the oxygen affinity of fetal Hb J-Sardegna is identical to that of normal fetal haemoglobin, both in the presence and in the absence of 2,3-DPG. A significant difference between these two systems (i.e. a higher oxygen affinity of fetal Hb J-Sardegna) shows up very clearly only when temperature is increased to 37 °C. Hence in fetal Hb, the main effect of the amino acid substitution is a decrease in the overall enthalpy change of oxygenation. The results outline the role of the α1-β1 interface in assessing the thermodynamics of oxygen binding. The functional properties of both adult and fetal Hb J-Sardegna have been interpreted at the structural level in light of the results obtained by a computational modelling approach performed in comparison with HbA and Hb Aichi, a variant characterized by a different mutation [α50(CE8)His → Arg] at the same position.

Erythrocyte Metabolism in Patients on Haemodialysis and Continuous Ambulatory Peritoneal Dialysis

1982 ◽  
Vol 62 (5) ◽  
pp. 479-488 ◽  
Author(s):  
G. P. Summerfield ◽  
A. J. Bellingham ◽  
L. Manlove ◽  
A. M. Forbes ◽  
H. J. Goldsmith
Keyword(s):  
Peritoneal Dialysis ◽  
Continuous Ambulatory Peritoneal Dialysis ◽  
Base Excess ◽  
Haemoglobin Concentration ◽  
Oxygen Affinity ◽  
Glucose Consumption ◽  
Plasma Phosphate ◽  
Glycolytic Intermediates ◽  
Erythrocyte Metabolism ◽  
2,3 Dpg

1. Erythrocyte metabolism was investigated and glycolytic intermediates were measured in nine patients with chronic renal failure who were subsequently treated with haemodialysis. The same' investigations were performed in nine patients on continuous ambulatory peritoneal dialysis (CAPD) who had previously been treated with intermittent peritoneal dialysis (IPD) (eight patients) or dietary restriction (one patient). 2. The patients who received haemodialysis had a partially compensated metabolic acidosis before treatment. With haemodialysis, plasma phosphate (Pi) fell and base excess, erythrocyte 2,3–diphosphoglycerate (2,3–DPG), glucose consumption and lactate production rose significantly. In this group the most important influence on erythrocyte metabolism was base excess. The pattern of erythrocyte glycolytic intermediates showed that the rise in 2,3–DPG with haemodialysis was brought about within the Rapoport—Luebering shunt; there was no statistically significant decrease in haemoglobin—oxygen affinity. 3. The patients who received CAPD were not acidotic before starting this form of treatment. With CAPD, there was a significant increase in haemoglobin and fall in plasma phosphate, erythrocyte 2,3–DPG and glucose consumption. The major factors influencing erythrocyte metabolism in this group were plasma phosphate and haemoglobin concentration. The fall in 2,3–DPG was produced by inhibition of 6-phosphofructokinase (EC 2.7.1.11); despite this fall, haemoglobin-oxygen affinity was not affected.

scholarly journals Physiological insight into the evolution of complex phenotypes: aerobic performance and the O2 transport pathway of vertebrates

2021 ◽  
Vol 224 (16) ◽  
Author(s):  
Graham R. Scott ◽  
Anne C. Dalziel
Keyword(s):  
Aerobic Capacity ◽  
Theoretical Modelling ◽  
Aerobic Performance ◽  
Population Divergence ◽  
Evolutionary Divergence ◽  
Evolutionary Physiology ◽  
Transport Pathway ◽  
O2 Transport ◽  
O2 Extraction ◽  
O2 Diffusion

ABSTRACT Evolutionary physiology strives to understand how the function and integration of physiological systems influence the way in which organisms evolve. Studies of the O2 transport pathway – the integrated physiological system that transports O2 from the environment to mitochondria – are well suited to this endeavour. We consider the mechanistic underpinnings across the O2 pathway for the evolution of aerobic capacity, focusing on studies of artificial selection and naturally selected divergence among wild populations of mammals and fish. We show that evolved changes in aerobic capacity do not require concerted changes across the O2 pathway and can arise quickly from changes in one or a subset of pathway steps. Population divergence in aerobic capacity can be associated with the evolution of plasticity in response to environmental variation or activity. In some cases, initial evolutionary divergence of aerobic capacity arose exclusively from increased capacities for O2 diffusion and/or utilization in active O2-consuming tissues (muscle), which may often constitute first steps in adaptation. However, continued selection leading to greater divergence in aerobic capacity is often associated with increased capacities for circulatory and pulmonary O2 transport. Increases in tissue O2 diffusing capacity may augment the adaptive benefit of increasing circulatory O2 transport owing to their interactive influence on tissue O2 extraction. Theoretical modelling of the O2 pathway suggests that O2 pathway steps with a disproportionately large influence over aerobic capacity have been more likely to evolve, but more work is needed to appreciate the extent to which such physiological principles can predict evolutionary outcomes.

scholarly journals The Circulatory Response to Acute Hypoxia in Octopus

1983 ◽  
Vol 104 (1) ◽  
pp. 59-71 ◽  
Author(s):  
M.J. WELLS ◽  
J. WELLS
Keyword(s):  
Oxygen Uptake ◽  
Acute Hypoxia ◽  
Oxygen Affinity ◽  
Octopus Vulgaris ◽  
Blood Oxygen ◽  
Total Oxygen ◽  
Circulatory Response ◽  
The Central Nervous System ◽  
Blood Oxygen Affinity ◽  
Cutaneous Respiration

Octopus vulgaris can regulate its oxygen uptake in a closed respirometer down to a Poo2 of less than 70 mmHg. As the tankwater Poo2 falls the hearts slow down. Pulse amplitudes and mean pressures fall in the afferent branchial vessels and in the dorsal aorta. Despite behavioural changes - expansion of the interbrachial web and extension of the arms - that might imply this, the proportion of the total oxygen uptake attributable to cutaneous respiration (less than 13%) does not alter as the external Poo2 falls. The response of the hearts to a low Poo2 is not affected by severing the nerve supply from the central nervous system, or by removal of the heart ganglia. It is evidently determined by oxygen lack and not by the accumulation of CO2 or other metabolites, since the same effects are achieved by placing the animals in water where the Poo2 has been reduced by boiling. The conclusion that regulation does not depend upon circulatory responses to hypoxia is considered in the light of recent work on the changes in blood oxygen affinity associated with acute hypoxia in cephalopods.

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