scholarly journals Bi-exponential modelling of $$W^{^{\prime}}$$ reconstitution kinetics in trained cyclists

2021 ◽  
Author(s):  
Alan Chorley ◽  
Richard P. Bott ◽  
Simon Marwood ◽  
Kevin L. Lamb
Keyword(s):  
Time Constant ◽  
Slow Component ◽  
Information Criterion ◽  
Exponential Model ◽  
Large Individual ◽  
Individual Parameter ◽  
Exponential Models ◽  
Ramp Exercise ◽  
The Individual ◽  
W Prime

Abstract Purpose The aim of this study was to investigate the individual $$W^{^{\prime}}$$ W ′ reconstitution kinetics of trained cyclists following repeated bouts of incremental ramp exercise, and to determine an optimal mathematical model to describe $$W^{^{\prime}}$$ W ′ reconstitution. Methods Ten trained cyclists (age 41 ± 10 years; mass 73.4 ± 9.9 kg; $$\dot{V}{\text{O}}_{2\max }$$ V ˙ O 2 max 58.6 ± 7.1 mL kg min−1) completed three incremental ramps (20 W min−1) to the limit of tolerance with varying recovery durations (15–360 s) on 5–9 occasions. $$W^{^{\prime}}$$ W ′ reconstitution was measured following the first and second recovery periods against which mono-exponential and bi-exponential models were compared with adjusted R2 and bias-corrected Akaike information criterion (AICc). Results A bi-exponential model outperformed the mono-exponential model of $$W^{^{\prime}}$$ W ′ reconstitution (AICc 30.2 versus 72.2), fitting group mean data well (adjR2 = 0.999) for the first recovery when optimised with parameters of fast component (FC) amplitude = 50.67%; slow component (SC) amplitude = 49.33%; time constant (τ)FC = 21.5 s; τSC = 388 s. Following the second recovery, W′ reconstitution reduced by 9.1 ± 7.3%, at 180 s and 8.2 ± 9.8% at 240 s resulting in an increase in the modelled τSC to 716 s with τFC unchanged. Individual bi-exponential models also fit well (adjR2 = 0.978 ± 0.017) with large individual parameter variations (FC amplitude 47.7 ± 17.8%; first recovery: (τ)FC = 22.0 ± 11.8 s; (τ)SC = 377 ± 100 s; second recovery: (τ)FC = 16.3.0 ± 6.6 s; (τ)SC = 549 ± 226 s). Conclusions W′ reconstitution kinetics were best described by a bi-exponential model consisting of distinct fast and slow phases. The amplitudes of the FC and SC remained unchanged with repeated bouts, with a slowing of W′ reconstitution confined to an increase in the time constant of the slow component.

V˙o 2 kinetics in the horse during moderate and heavy exercise

1997 ◽  
Vol 83 (4) ◽  
pp. 1235-1241 ◽  
Author(s):  
I. Langsetmo ◽  
G. E. Weigle ◽  
M. R. Fedde ◽  
H. H. Erickson ◽  
T. J. Barstow ◽  
...  
Keyword(s):  
Time Constant ◽  
Slow Component ◽  
Venous Blood ◽  
Exponential Model ◽  
Mixed Venous Blood ◽  
Phase 2 ◽  
Heavy Exercise ◽  
Two Phase ◽  
Treadmill Testing ◽  
Exercise Transitions

Langsetmo, I., G. E. Weigle, M. R. Fedde, H. H. Erickson, T. J. Barstow, and D. C. Poole.V˙o 2 kinetics in the horse during moderate and heavy exercise. J. Appl. Physiol. 83(4): 1235–1241, 1997.—The horse is a superb athlete, achieving a maximal O2 uptake (∼160 ml ⋅ min−1 ⋅ kg−1) approaching twice that of the fittest humans. Although equine O2 uptake (V˙o 2) kinetics are reportedly fast, they have not been precisely characterized, nor has their exercise intensity dependence been elucidated. To address these issues, adult male horses underwent incremental treadmill testing to determine their lactate threshold (Tlac) and peakV˙o 2(V˙o 2 peak), and kinetic features of theirV˙o 2 response to “square-wave” work forcings were resolved using exercise transitions from 3 m/s to a below-Tlac speed of 7 m/s or an above-Tlac speed of 12.3 ± 0.7 m/s (i.e., between Tlac andV˙o 2 peak) sustained for 6 min. V˙o 2 and CO2 output were measured using an open-flow system: pulmonary artery temperature was monitored, and mixed venous blood was sampled for plasma lactate.V˙o 2 kinetics at work levels below Tlac were well fit by a two-phase exponential model, with a phase 2 time constant (τ1 = 10.0 ± 0.9 s) that followed a time delay (TD1 = 18.9 ± 1.9 s). TD1 was similar to that found in humans performing leg cycling exercise, but the time constant was substantially faster. For speeds above Tlac, TD1 was unchanged (20.3 ± 1.2 s); however, the phase 2 time constant was significantly slower (τ1 = 20.7 ± 3.4 s, P < 0.05) than for exercise below Tlac. Furthermore, in four of five horses, a secondary, delayed increase inV˙o 2 became evident 135.7 ± 28.5 s after the exercise transition. This “slow component” accounted for ∼12% (5.8 ± 2.7 l/min) of the net increase in exercise V˙o 2. We conclude that, at exercise intensities below and above Tlac, qualitative features ofV˙o 2 kinetics in the horse are similar to those in humans. However, at speeds below Tlac the fast component of the response is more rapid than that reported for humans, likely reflecting different energetics of O2utilization within equine muscle fibers.

scholarly journals O2 uptake kinetics during exercise at peak O2 uptake

2003 ◽  
Vol 95 (5) ◽  
pp. 2014-2022 ◽  
Author(s):  
Barry W. Scheuermann ◽  
Thomas J. Barstow
Keyword(s):  
Time Constant ◽  
Slow Component ◽  
Motor Units ◽  
Oxidative Capacity ◽  
Exponential Model ◽  
Primary Component ◽  
Moderate Intensity ◽  
O2 Uptake ◽  
Ergometer Exercise ◽  
Severe Intensity

Compared with moderate- and heavy-intensity exercise, the adjustment of O2 uptake (V̇o2) to exercise intensities that elicit peak V̇o2 has received relatively little attention. This study examined the V̇o2 response of 21 young, healthy subjects (25 ± 6 yr; mean ± SD) during cycle ergometer exercise to step transitions in work rate (WR) corresponding to 90, 100, and 110% of the peak WR achieved during a preliminary ramp protocol (15-30 W/min). Gas exchange was measured breath by breath and interpolated to 1-s values. V̇o2 kinetics were determined by use of a two- or three-component exponential model to isolate the time constant (τ2) as representative of V̇o2 kinetics and the amplitude (Amp) of the primary fast component independent of the appearance of any V̇o2 slow component. No difference in V̇o2 kinetics was observed between WRs (τ90 = 24.7 ± 9.0; τ100 = 22.8 ± 6.7; τ110 = 21.5 ± 9.2 s, where subscripts denote percent of peak WR; P > 0.05); nor in a subgroup of eight subjects was τ2 different from the value for moderate-intensity (<lactate threshold) exercise (τ2 = 25 ± 12 s, P > 0.05). As expected, the Amp increased with increasing WRs (Amp90 = 2,089 ± 548; Amp100 = 2,165 ± 517; Amp110 = 2,225 ± 559 ml/min; Amp90 vs. Amp110, P < 0.05). However, the gain (G) of the V̇o2 response (ΔV̇o2/ΔWR) decreased with increasing WRs (G90 = 8.5 ± 0.6; G100 = 7.9 ± 0.6; G110 = 7.3 ± 0.6 ml·min-1·W-1; P < 0.05). The Amp of the primary component approximated 85, 88, and 89% of peak V̇o2 during 90, 100, and 110% WR transitions, respectively. The results of the present study demonstrate that, compared with moderate- and heavy-intensity exercise, the gain of the V̇o2 response (as ΔV̇o2/ΔWR) is reduced for exercise transitions in the severe-intensity domain, but the approach to this gain is well described by a common time constant that is invariant across work intensities. The lower ΔV̇o2/ΔWR may be due to an insufficient adjustment of the cardiovascular and/or pulmonary systems that determine O2 delivery to the exercising muscles or due to recruitment of motor units with lower oxidative capacity, after the onset of exercise in the severe-intensity domain.

scholarly journals 101 Evaluation of Growth Curve Functions for predicted weight in small holder crossbred dairy cattle in Tanzania

2020 ◽  
Vol 98 (Supplement_4) ◽  
pp. 79-80
Author(s):  
Chinyere Ekine ◽  
Raphael Mrode ◽  
Edwin Oyieng ◽  
Daniel Komwihangilo ◽  
Gilbert Msuta ◽  
...  
Keyword(s):  
Growth Curve ◽  
Model Comparison ◽  
Predictive Ability ◽  
Nonlinear Least Squares ◽  
Information Criterion ◽  
Dairy Farms ◽  
Exponential Model ◽  
Males And Females ◽  
Small Holder ◽  
Two Parameter

Abstract Modelling the growth curve of animals provides information on growth characteristics and is important for optimizing management in different livestock systems. This study evaluated the growth curves of crossbred calves from birth to 30 months of age in small holder dairy farms in Tanzania using a two parameter (exponential), four different three parameters (Logistic, von Bertalanffy, Brody, Gompertz), and three polynomial functions. Predicted weights based on heart girth measurements of 623 male and 846 female calves born between 2016 and 2019 used in this study were from the African Dairy Genetic Gains (ADGG) project in selected milk sheds in Tanzania, namely Tanga, Kilimanjaro, Arusha, Iringa, Njomba and Mbeya. Each function was fitted separately to weight measurement of males and females adjusted for the effect of ward and season of birth using the nonlinear least squares (nls) functions in R statistical software. The Akaike’s information criterion (AIC) and Bayesian information criterion (BIC) were used for model comparison. Based on these criteria, all three polynomial and four parameter functions performed better and did not differ enough from each other in both males and females compared to the two-parameter exponential model. Predicted weight varied among the models and differed between males and females. The highest estimated weight was observed in the Brody model for both males (278.09 kg) and females (264.10 kg). Lowest estimated weight was observed in the exponential model. Estimated growth rate varied among models. For males, it ranged from 0.04 kg-0.08 kg and for females, from 0.05 kg-0.09 kg in the Brody model and logistic model respectively. Predictive ability across all fitted curves was low, ranging from 25% to approximately 29%. This could be due to the huge range of breed compositions in the evaluated crossbred calves which characterizes small holder dairy farms in this system and different levels of farm management.

scholarly journals Wormhole Solutions in Symmetric Teleparallel Gravity with Noncommutative Geometry

Symmetry ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1260
Author(s):  
Zinnat Hassan ◽  
Ghulam Mustafa ◽  
Pradyumn Kumar Sahoo
Keyword(s):  
Linear Model ◽  
Noncommutative Geometry ◽  
Teleparallel Gravity ◽  
Exponential Model ◽  
Model Parameter ◽  
Exponential Models ◽  
Feasible Solutions ◽  
The Stability ◽  
Tov Equation

This article describes the study of wormhole solutions in f(Q) gravity with noncommutative geometry. Here, we considered two different f(Q) models—a linear model f(Q)=αQ and an exponential model f(Q)=Q−α1−e−Q, where Q is the non-metricity and α is the model parameter. In addition, we discussed the existence of wormhole solutions with the help of the Gaussian and Lorentzian distributions of these linear and exponential models. We investigated the feasible solutions and graphically analyzed the different properties of these models by taking appropriate values for the parameter. Moreover, we used the Tolman–Oppenheimer–Volkov (TOV) equation to check the stability of the wormhole solutions that we obtained. Hence, we found that the wormhole solutions obtained with our models are physically capable and stable.

Effects of Normobaric Hypoxia on Matched-severe Exercise and Power-duration Relationship

2021 ◽  
Author(s):  
Ana Catarina Sousa ◽  
Gregoire P. Millet ◽  
João Viana ◽  
Jaime Milheiro ◽  
Vítor Reis
Keyword(s):  
Relative Intensity ◽  
Slow Component ◽  
Exponential Model ◽  
Normobaric Hypoxia ◽  
Time To Exhaustion ◽  
V̇o2 Kinetics ◽  
Severe Intensity ◽  
Lower Oxygen ◽  
Severe Exercise ◽  
Duration Relationship

AbstractWe investigated the effects of hypoxia on matched-severe intensity exercise and on the parameters of the power-duration relationship. Fifteen trained subjects performed in both normoxia and normobaric hypoxia (FiO2=0.13, ~3000 m) a maximal incremental test, a 3 min all-out test (3AOT) and a transition from rest to an exercise performed to exhaustion (Tlim) at the same relative intensity (80%∆). Respiratory and pulmonary gas-exchange variables were continuously measured (K5, Cosmed, Italy). Tlim test’s V̇O2 kinetics was calculated using a two-component exponential model. V̇O2max (44.1±5.1 vs. 58.7±6.4 ml.kg-1.min-1, p<0.001) was decreased in hypoxia. In Tlim, time-to-exhaustion sustained was similar (454±130 vs. 484±169 s) despite that V̇O2 kinetics was slower (τ1: 31.1±5.8 vs. 21.6±4.7 s, p<0.001) and the amplitude of the V̇O2 slow component lower (12.4±5.4 vs. 20.2±5.7 ml.kg-1.min-1, p<0.05) in hypoxia. CP was reduced (225±35 vs. 270±49 W, p<0.001) but W’ was unchanged (11.3±2.9 vs. 11.4±2.7 kJ) in hypoxia. The changes in CP/V̇O2max were positively correlated with changes in W’ (r = 0.58, p<0.05). The lower oxygen availability had an impact on aerobic related physiological parameters, but exercise tolerance is similar between hypoxia and normoxia when the relative intensity is matched despite a slower V̇O2 kinetics in hypoxia.

Longitudinal changes in the kinetic response to heavy-intensity exercise in children

2004 ◽  
Vol 97 (2) ◽  
pp. 460-466 ◽  
Author(s):  
Samantha G. Fawkner ◽  
Neil Armstrong
Keyword(s):  
Slow Component ◽  
Phase 1 ◽  
Exponential Model ◽  
Cycle Ergometer ◽  
Primary Component ◽  
Total Change ◽  
Exercise Tests ◽  
Longitudinal Changes ◽  
Dependent Change ◽  
The Difference

The purpose of this study was to investigate longitudinal changes with age in the kinetic response to cycling at heavy-intensity exercise in boys and girls. Twenty-two prepubertal children (13 male, 9 female) carried out a series of exercise tests on two test occasions with a 2-yr interval. On each test occasion, the subject completed multiple transitions from baseline to 40% of the difference between their previously determined V-slope and peak O2 uptake (V̇o2) for 9 min on an electronically braked cycle ergometer. Each subject's breath-by-breath responses were interpolated to 1-s intervals, time aligned, and averaged. The data after phase 1 were fit with 1) a double exponential model and 2) a single exponential model within a fitting window that was previously identified to exclude the slow component. There were no significant differences in the parameters of the primary component between each model. Subsequent analysis was carried out using model 2. The V̇o2 slow component was computed as the difference between the amplitude of the primary component and the end-exercise V̇o2 and was expressed as the percent contribution to the total change in V̇o2. Over the 2-yr period, the primary time constant (boys 16.8 ± 5.3 and 21.7 ± 5.3 s, girls 21.1 ± 8.1 and 26.4 ± 8.4 s, first and second occasion, respectively) and the relative amplitude of the slow component (boys 9.4 ± 4.6 and 13.8 ± 5.3%, girls 10.3 ± 2.4 and 15.5 ± 2.8%, first and second occasion, respectively) significantly increased with no sex differences. The data demonstrate that children do display a slow-component response to exercise and are consistent with an age-dependent change in the muscles' potential for O2 utilization.

scholarly journals CNV Neurons Are Rare in Aged Human Neocortex

2018 ◽  
Author(s):  
William D. Chronister ◽  
Margaret B. Wierman ◽  
Ian E. Burbulis ◽  
Matthew J. Wolpert ◽  
Mark F. Haakenson ◽  
...  
Keyword(s):  
Copy Number Variants ◽  
Allelic Diversity ◽  
Population Level ◽  
Information Criterion ◽  
Published Data ◽  
Tissue Quality ◽  
Cell Library ◽  
Detection Approach ◽  
Human Neurons ◽  
The Individual

AbstractMegabase-scale somatic copy number variants (CNVs) alter allelic diversity in a subset of human neocortical neurons. Reported frequencies of CNV neurons range from ∼5% of neurons in some individuals to greater than 30% in other individuals. Genome-wide and familial studies implicitly assume a constant brain genome when assessing the genetic risk architecture of neurological disease, thus it is critical to determine whether divergent reports of CNV neuron frequency reflect normal individual variation or technical differences between approaches. We generated a new dataset of over 800 human neurons from 5 neurotypical individuals and developed a computational approach that measures single cell library quality based on Bayesian Information Criterion and identifies integer-like variant segments from population-level statistics. A brain CNV atlas was assembled using our new dataset and published data from 10 additional neurotypical individuals. This atlas reveals that the frequency of neocortical CNV neurons varies widely among individuals, but that this variability is not readily accounted for by tissue quality or CNV detection approach. Rather, the age of the individual is anti-correlated with CNV neuron frequency. Fewer CNV neurons are observed in aged individuals than young individuals.

Text and Discourse Linguistic Creativity of Children's English-Language Adventure Fiction

2021 ◽  
pp. 5-15
Author(s):  
Maria I. Kiose ◽  
◽  
Keyword(s):  
Vector Space ◽  
English Language ◽  
Total Sample ◽  
Word Formation ◽  
Statistics Analysis ◽  
Individual Parameter ◽  
Creativity Assessment ◽  
Adventure Fiction ◽  
The Individual ◽  
Parameter Values

The article explores the specificity of linguistic creativity in the discourse of children's English-language adventure fiction of the 1950s. The aim of the research is to develop the parametrization and vector-space method of discourse and text linguistic creativity assessment to evaluate the linguistic creativity potential of individual texts displaying similar discourse features. To serve as the research data three discourse fragments were selected, which represent three basic narrative types, Orientation, Complicating Actions, Evaluation and Resolution. To achieve the aim, the author applies the procedure of parametrization analysis followed by general and analytic statistics analysis and vector-space modelling. With the system of 52 parameters featuring linguistic creativity in phonology, word-formation, morphology, lexicology and phraseology, syntax, and graphics, the author manually annotates and processes the discourse fragments of similar size exemplifying three narrative types of adventure fiction literature, with the total sample size of 55,000 characters. General statistics analysis allowed revealing the absolute and relative parameter values in three discourse fragments and defining the relative parametric activity of single parameters and parameter levels. Analysis of variance helped define the correlation indices of parameter paired combinations, which resulted in detecting significant binary parameter groups . Individual parameter values and their binary groups served to construe the vector-space models of discourse and text linguistic creativity for the discourse narrative types under consideration. Thus, the author obtained an efficient instrument for discourse linguistic creativity evaluation and, furthermore, for assessing the potential of each individual text in terms of displaying stronger or weaker correlation with the vector coordinates of the discourse linguistic creativity vector-space model. With the frequency and variance analysis, the author disclosed two types of discourse linguistic creativity performance techniques, that is the individual parameter activation and the parameter synchronization. Both must be considered when the decision on linguistic creativity assessment in a concrete text is made. The resulting model shows that the parameter values of linguistic creativity in individual texts can manifest themselves in appearing both higher and lower than the reference parameter values of discourse creativity, which can contribute to disclosing new directions in creativity processing and understanding.

Study of Changes of the Individual Parameter of Resources in the Modelling of Renewable Systems

2019 ◽  
pp. 19-28
Author(s):  
Oleksandr Karelin ◽  
Anna Tarasenko ◽  
Oleksandr Barabash ◽  
Manuel Gonzalez-Hernandez ◽  
Joselito Medina-Marin
Keyword(s):  
Individual Parameter ◽  
The Individual

Two distinct inactivation processes related to phosphorylation in cardiac L-type Ca2+ channel currents

2000 ◽  
Vol 279 (3) ◽  
pp. C603-C610 ◽  
Author(s):  
Sayaka Mitarai ◽  
Muneshige Kaibara ◽  
Katsusuke Yano ◽  
Kohtaro Taniyama
Keyword(s):  
Membrane Potential ◽  
Protein Kinase ◽  
Time Constant ◽  
Kinase Inhibitor ◽  
Slow Component ◽  
Patch Clamp Technique ◽  
Whole Cell Patch Clamp ◽  
Inward Currents ◽  
Inactivation Process ◽  
Channel Currents

We investigated the inactivation process of macroscopic cardiac L-type Ca2+ channel currents using the whole cell patch-clamp technique with Na+ as the current carrier. The inactivation process of the inward currents carried by Na+ through the channel consisted of two components >0 mV. The time constant of the faster inactivating component (30.6 ± 2.2 ms at 0 mV) decreased with depolarization, but the time constant of the slower inactivating component (489 ± 21 ms at 0 mV) was not significantly influenced by the membrane potential. The inactivation process in the presence of isoproterenol (100 nM) consisted of a single component (538 ± 60 ms at 0 mV). A protein kinase inhibitor, H-89, decreased the currents and attenuated the effects of isoproterenol. In the presence of cAMP (500 μM), the inactivation process consisted of a single slow component. We propose that the faster inactivating component represents a kinetic of the dephosphorylated or partially phosphorylated channel, and phosphorylation converts the kinetics into one with a different voltage dependency.

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