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.

Effect of flow on O2 consumption during progressive hypoxemia

1988 ◽  
Vol 65 (2) ◽  
pp. 601-607 ◽  
Author(s):  
G. Gutierrez ◽  
R. J. Pohil ◽  
R. Strong
Keyword(s):  
Venous Blood ◽  
Blood Gases ◽  
Low Flow ◽  
Base Line ◽  
O2 Consumption ◽  
Experimental Protocol ◽  
O2 Transport ◽  
O2 Extraction ◽  
O2 Diffusion ◽  
Arterial Po2

Rabbit hindlimb preparations perfused with blood from donor rabbits were used to determine whether O2 consumption (VO2) during hypoxemia is limited by total O2 transport (TO2) or by capillary O2 driving pressure, as reflected by the venous PO2 (PVO2). The preparations were randomized into two groups: low flow (LF) and high flow (HF), perfused at 18 and 32 ml.min-1.kg of preparation wt-1, respectively. After a 1-h base-line period with arterial PO2 (PaO2) greater than 100 Torr, both groups were exposed to progressive decrements in PaO2 to less than 10 Torr. Sequential sets of arterial and venous blood gases were obtained, and VO2, TO2, and O2 extraction ratio (ERO2) were calculated. A plot of PVO2 vs. TO2 showed higher levels of PVO2 (P less than 0.05) in LF than HF, when compared at similar levels of TO2. Therefore the experimental protocol allowed the comparison of the separate effects of TO2 or PVO2 on VO2. Plotting VO2 as a function of TO2 revealed two distinct curves (P less than 0.05), with LF having a greater VO2 than HF at a given TO2. Conversely, a plot of VO2 as a function of PVO2 did not show a difference between the groups. The ERO2 of LF was greater than HF when compared at similar levels of TO2 (P less than 0.05). We conclude from these data that during progressive hypoxemia VO2 appears to be primarily limited by factors that determine capillary O2 diffusion. This conclusion supports the Kroghian theory of capillary O2 exchange.

Increased hemoglobin O2 affinity does not improve O2 consumption in hypoxemia

1989 ◽  
Vol 66 (2) ◽  
pp. 837-843 ◽  
Author(s):  
G. Gutierrez ◽  
J. M. Andry
Keyword(s):  
Hemoglobin Concentration ◽  
Resonance Spectroscopy ◽  
O2 Consumption ◽  
Comparable Rate ◽  
Perfusion Flow ◽  
O2 Transport ◽  
O2 Extraction ◽  
O2 Diffusion ◽  
Arterial O2 Saturation ◽  
Arterial Po2

We perfused an isolated rabbit hindlimb preparation with suspensions of human erythrocytes (RBC) having different O2 affinities. Our objective was to compare the effect of changes in P50, the PO2 at which hemoglobin is 50% saturated, on tissue O2 consumption during severe hypoxemia. A high-affinity (HA) group (n = 9) was perfused with RBC incubated in NaCNO (P50 = 21.4 +/- 1.9 Torr). This was compared with a low-affinity (LA) group (n = 9) perfused with rejuvenated RBC (P50 = 31.1 +/- 1.8 Torr). The arterial PO2 of the perfusate was decreased to approximately 24 Torr in both preparations. Perfusion flow and hemoglobin concentration were maintained constant. During hypoxemia arterial O2 saturation and total O2 transport (TO2) were greater in the HA than the LA group (P less than 0.05). O2 consumption and effluent venous PO2 decreased with hypoxemia in both groups to similar levels. Consequently, the LA group showed a greater O2 extraction ratio than the HA group (P less than 0.05). The ratio of phosphocreatine to inorganic phosphate, measured with 31P magnetic resonance spectroscopy, decreased at a comparable rate in both groups. As shown by a mathematical model of peripheral O2 transport, these experimental results can be explained on the basis of peripheral limitation to O2 diffusion. We conclude that increased hemoglobin affinity does not appreciably improve tissue oxygenation in hypoxemia, since the increase in TO2 is offset by diffusion limitation at the tissues.

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 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.

Phosphate supplementation, cardiovascular function, and exercise performance in humans

1988 ◽  
Vol 65 (4) ◽  
pp. 1821-1826 ◽  
Author(s):  
D. L. Bredle ◽  
J. M. Stager ◽  
W. F. Brechue ◽  
M. O. Farber
Keyword(s):  
Aerobic Capacity ◽  
Work Performance ◽  
Saturation Pressure ◽  
Cardiovascular Function ◽  
Time To Exhaustion ◽  
Vo2 Max ◽  
Maximal Aerobic Capacity ◽  
Double Blind ◽  
O2 Extraction ◽  
Peripheral Effect

The use of oral phosphate (Pi) supplements to improve muscular work performance has long been proposed without substantiating data. In a double-blind, crossover experiment 11 male runners ingested calcium Pi (176 mmol/day) or placebo for 4 days. On the 3rd treatment day, subjects ran an incremental maximal aerobic capacity test (VO2 max) on a treadmill, and on the 4th day a treadmill run to exhaustion at approximately 70% VO2max. By the 4th day of Pi loading, plasma Pi was significantly higher than control (P less than 0.05); however, erythrocyte Pi, 2,3-diphosphoglycerate, and O2 half-saturation pressure of hemoglobin (P50) were not elevated. VO2 max was not changed by the treatments (mean 62.9, 64.2, 64.9 ml.kg-1.min-1 for control, Pi, and placebo bouts, respectively) nor was submaximal run time to exhaustion (61.6 min for Pi, 65.5 min for placebo). Stroke volume at steady-state VO2 was decreased with Pi (P less than 0.05), whereas cardiac output tended (P = 0.07) to be lower. Greater arteriovenous O2 difference (P less than 0.05) with Pi suggested a peripheral effect that increased O2 extraction. We concluded that in healthy individuals Pi loading produced no improvement in work tolerance or aerobic capacity but did alter some aspects of cardiovascular function.

Comparison of the cardiac pumping capability and cardiac pumping reserve in double-muscled and conventional calves

1993 ◽  
Vol 71 (12) ◽  
pp. 946-951 ◽  
Author(s):  
H. Amory ◽  
K. McEntee ◽  
A. S. Linden ◽  
D. J. M. Desmecht ◽  
J. M. L. Beduin ◽  
...  
Keyword(s):  
Heart Rate ◽  
Aerobic Capacity ◽  
Power Output ◽  
Cardiac Performance ◽  
Muscular Hypertrophy ◽  
Transport Pathway ◽  
Cardiac Reserve ◽  
Cardiac Power ◽  
Cardiac Pumping ◽  
Pulmonary Arterial

Hereditary muscular hypertrophy is a character that has been selected in several animal species for industrial meat production. The selection of this character in cattle produces animals of exceptional commercial value but ones with a lower aerobic capacity than that of conventional cattle. The purpose of this work was to study the role of cardiac function as a potential limiting factor of aerobic capacity in double-muscled calves. Two groups of healthy calves were studied, one consisting of nine calves of conventional conformation and the other of nine double-muscled calves. Pulmonary arterial and capillary wedge, central venous, and systemic arterial pressures were measured by fluid-filled catheters and recorded together with the electrocardiogram. Cardiac output was measured by the thermodilution technique. From these measurements, the heart rate, the cardiac and the stroke indices, the pulmonary and the systemic vascular resistances, and the cardiac power output were calculated. The parameters were recorded under basal resting conditions and during incremental dobutamine challenge, which allowed determination of the resting cardiac power output, the cardiac pumping capability, and the cardiac reserve. Dobutamine challenge induced a significant rise in cardiac and stroke indices, heart rate, and cardiac power output, a significant decrease in pulmonary and systemic vascular resistances, and no change in systemic and pulmonary arterial pressures. The cardiac reserve obtained in the present study was low in comparison with those previously reported in humans, dogs, and horses. This may be related to the poor running capability of bovine species relative to that of the former species. The double-muscled calves had significantly lower cardiac and stroke indices, resting cardiac power output, cardiac pumping capability, and cardiac reserve than did conventional calves. Therefore, the cardiac performance, capability, and reserve were reduced in double-muscled calves. It was concluded that cardiac performance is a critical step in the oxygen-transport pathway in double-muscled cattle.Key words: cattle, hereditary muscular hypertrophy, oxygen consumption, cardiovascular system, cardiac power output.

scholarly journals Steady-State, Hemoglobin-Facilitated O2 Transport in Human Erythrocytes

1969 ◽  
Vol 53 (5) ◽  
pp. 576-589 ◽  
Author(s):  
Howard Kutchai ◽  
Norman C. Staub
Keyword(s):  
Steady State ◽  
Facilitated Transport ◽  
Diffusion Resistance ◽  
Red Cell Membrane ◽  
Equal Concentration ◽  
O2 Transport ◽  
Carrier Molecule ◽  
O2 Diffusion ◽  
Carbon Monoxide Binding ◽  
Hb Concentration

We measured the rate of oxygen transport through thin (165 µ) films of packed erythrocytes (Hb concentration = 30 g/100 ml). Under optimal conditions steady-state O2 diffusion was nearly three times that found when the hemoglobin was prevented from acting as a carrier molecule by carbon monoxide binding or high oxygen back pressure. After each experiment we measured hemolysis and found that it averaged less than 1%. Hemolysis could not account for the facilitation, thus proving that facilitated transport of O2 by hemoglobin can occur in red blood cells. The rate of facilitated transport was identical for Hb solutions of equal concentration to the cells. We interpret this to mean that under the conditions of our experiments the red cell membrane offers no detectable diffusion resistance to O2 and that the mobility of Hb in intact red cells is the same as in concentrated Hb solution.

scholarly journals Interval Versus Continuous Training With Identical Workload: Physiological and Aerobic Capacity Adaptations

2015 ◽  
pp. 209-219 ◽  
Author(s):  
G. G. DE ARAUJO ◽  
C. A. GOBATTO ◽  
M. MARCOS-PEREIRA ◽  
I. G. M. DOS REIS ◽  
R. VERLENGIA
Keyword(s):  
Aerobic Capacity ◽  
Recovery Period ◽  
Training Session ◽  
Interval Training ◽  
Experimental Period ◽  
Aerobic Performance ◽  
Continuous Training ◽  
Corticosterone Concentration ◽  
Interval Model ◽  
Equivalent Load

The interval model training has been more recommended to promote aerobic adaptations due to recovery period that enables the execution of elevated intensity and as consequence, higher workload in relation to continuous training. However, the physiological and aerobic capacity adaptations in interval training with identical workload to continuous are still uncertain. The purpose was to characterize the effects of chronic and acute biomarkers adaptations and aerobic capacity in interval and continuous protocols with equivalent load. Fifty Wistar rats were divided in three groups: Continuous training (GTC), interval training (GTI) and control (CG). The running training lasted 8 weeks (wk) and was based at Anaerobic Threshold (AT) velocity. GTI showed glycogen super-compensation (mg/100 mg) 48 h after training session in relation to CG and GTC (GTI red gastrocnemius (RG)=1.41±0.16; GTI white gastrocnemius (WG)=1.78±0.20; GTI soleus (S)=0.26±0.01; GTI liver (L)=2.72±0.36; GTC RG=0.42±0.17; GTC WG=0.54±0.22; GTC S=0.100±0.01; GTC L=1.12±0.24; CG RG=0.32±0.05; CG WG=0.65±0.17; CG S=0.14±0.01; CG L=2.28±0.33). The volume performed by GTI was higher than GTC. The aerobic capacity reduced 11 % after experimental period in GTC when compared to GTI, but this change was insignificant (19.6±5.4 m/min; 17.7±2.5 m/min, effect size = 0.59). Free fatty acids and glucose concentration did not show statistical differences among the groups. Corticosterone concentration increased in acute condition for GTI and GTC. Testosterone concentration reduced 71 % in GTC immediately after the exercise in comparison to CG. The GTI allowed positive adaptations when compared to GTC in relation to: glycogen super-compensation, training volume performed and anabolic condition. However, the GTI not improved the aerobic performance.

scholarly journals The mechanistic basis of aerobic performance variation in red junglefowl

2000 ◽  
Vol 203 (13) ◽  
pp. 2053-2064 ◽  
Author(s):  
K.A. Hammond ◽  
M.A. Chappell ◽  
R.A. Cardullo ◽  
R. Lin ◽  
T.S. Johnsen
Keyword(s):  
Aerobic Capacity ◽  
Citrate Synthase ◽  
Social Rank ◽  
Reproductive Organs ◽  
Male Dominance ◽  
Aerobic Performance ◽  
Aerobic Scope ◽  
Leg Muscles ◽  
Red Junglefowl ◽  
Mechanistic Basis

We examined aerobic performance, organ and muscle mass and enzymatic activity in red junglefowl (Gallus gallus). We tested three models of performance limitation (central limits, peripheral limits, symmorphosis) and explored relationships between basal metabolic rate (BMR), aerobic capacity (V (O2max)) and social rank. Males had a lower BMR, a higher V (O2max) and a greater aerobic scope than females. Females possessed larger peritoneal and reproductive organs, while males had larger hearts, lungs and leg muscles. In females, BMR was correlated with spleen mass and V (O2max) was correlated with hematocrit and large intestine mass. Male BMR was correlated with intestinal tract and lung mass, and V (O2max) was correlated with heart and pectoralis mass. Male citrate synthase activity averaged 57 % higher than that of females and was correlated with V (O2max) (this correlation was not significant in females). Female social status was not correlated with any variable, but male dominance was associated with higher aerobic scope, larger heart and lungs, smaller peritoneal organs and greater leg citrate synthase activity. We conclude that aerobic capacity is controlled by system-wide limitations (symmorphosis) in males, while in females it is controlled by central organs. In neither sex is elevated aerobic capacity associated with increased maintenance costs.

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