scholarly journals Effect of Mathematical Modeling and Fitting Procedures on the Assessment of Critical Speed and Its Relationship With Aerobic Fitness Parameters

2021 ◽  
Vol 12 ◽  
Author(s):  
Aurélien Patoz ◽  
Nicola Pedrani ◽  
Romain Spicher ◽  
André Berchtold ◽  
Fabio Borrani ◽  
...  
Keyword(s):  
Mathematical Model ◽  
Aerobic Fitness ◽  
Critical Speed ◽  
Ventilatory Threshold ◽  
Information Criterion ◽  
Accurate Estimation ◽  
Running Speed ◽  
Fitting Procedure ◽  
Fitting Procedures ◽  
Fitness Parameters

An accurate estimation of critical speed (CS) is important to accurately define the boundary between heavy and severe intensity domains when prescribing exercise. Hence, our aim was to compare CS estimates obtained by statistically appropriate fitting procedures, i.e., regression analyses that correctly consider the dependent variables of the underlying models. A second aim was to determine the correlations between estimated CS and aerobic fitness parameters, i.e., ventilatory threshold, respiratory compensation point, and maximal rate of oxygen uptake. Sixteen male runners performed a maximal incremental aerobic test and four exhaustive runs at 90, 100, 110, and 120% of the peak speed of the incremental test on a treadmill. Then, two mathematically equivalent formulations (time as function of running speed and distance as function of running speed) of three different mathematical models (two-parameter, three-parameter, and three-parameter exponential) were employed to estimate CS, the distance that can be run above CS (d′), and if applicable, the maximal instantaneous running speed (smax). A significant effect of the mathematical model was observed when estimating CS, d′, and smax (P < 0.001), but there was no effect of the fitting procedure (P > 0.77). The three-parameter model had the best fit quality (smallest Akaike information criterion) of the CS estimates but the highest 90% confidence intervals and combined standard error of estimates (%SEE). The 90% CI and %SEE were similar when comparing the two fitting procedures for a given model. High and very high correlations were obtained between CS and aerobic fitness parameters for the three different models (r ≥ 0.77) as well as reasonably small SEE (SEE ≤ 6.8%). However, our results showed no further support for selecting the best mathematical model to estimate critical speed. Nonetheless, we suggest coaches choosing a mathematical model beforehand to define intensity domains and maintaining it over the running seasons.

scholarly journals Critical speed estimated by statistically appropriate fitting procedures

2021 ◽  
Author(s):  
Aurélien Patoz ◽  
Romain Spicher ◽  
Nicola Pedrani ◽  
Davide Malatesta ◽  
Fabio Borrani
Keyword(s):  
Critical Speed ◽  
Least Square ◽  
Accurate Estimation ◽  
Running Speed ◽  
Fitting Procedure ◽  
Model Variant ◽  
Fitting Procedures ◽  
Systematic Biases ◽  
Peak Speed ◽  
Two Parameter

Abstract Purpose Intensity domains are recommended when prescribing exercise. The distinction between heavy and severe domains is made by the critical speed (CS), therefore requiring a mathematically accurate estimation of CS. The different model variants (distance versus time, running speed versus time, time versus running speed, and distance versus running speed) are mathematically equivalent. Nevertheless, error minimization along the correct axis is important to estimate CS and the distance that can be run above CS (d′). We hypothesized that comparing statistically appropriate fitting procedures, which minimize the error along the axis corresponding to the properly identified dependent variable, should provide similar estimations of CS and d′ but that different estimations should be obtained when comparing statistically appropriate and inappropriate fitting procedure. Methods Sixteen male runners performed a maximal incremental aerobic test and four exhaustive runs at 90, 100, 110, and 120% of their peak speed on a treadmill. Several fitting procedures (a combination of a two-parameter model variant and regression analysis: weighted least square) were used to estimate CS and d′. Results Systematic biases (P < 0.001) were observed between each pair of fitting procedures for CS and d′, even when comparing two statistically appropriate fitting procedures, though negligible, thus corroborating the hypothesis. Conclusion The differences suggest that a statistically appropriate fitting procedure should be chosen beforehand by the researcher. This is also important for coaches that need to prescribe training sessions to their athletes based on exercise intensity, and their choice should be maintained over the running seasons.

Maximal and submaximal aerobic fitness in postmenopausal women: influence of hormone-replacement therapy

2008 ◽  
Vol 33 (5) ◽  
pp. 922-928 ◽  
Author(s):  
Liza Stathokostas ◽  
John M. Kowalchuk ◽  
Robert J. Petrella ◽  
Donald H. Paterson
Keyword(s):  
Oxygen Consumption ◽  
Hormone Replacement Therapy ◽  
Replacement Therapy ◽  
Postmenopausal Women ◽  
Body Mass ◽  
Aerobic Fitness ◽  
Ventilatory Threshold ◽  
Hormone Replacement ◽  
Peak Oxygen Consumption ◽  
Fitness Parameters

The purpose of this study was to examine whether maximal and submaximal aerobic fitness parameters (peak oxygen consumption and ventilatory threshold, respectively) are affected by hormone-replacement therapy (HRT) in moderately active postmenopausal women. Forty healthy, active, postmenopausal women (21 taking HRT, mean age 62 ± 5 years; 19 not taking HRT, mean age 62 ± 7 years) met the peak oxygen consumption criteria during a cycle ergometer test (15 W ramp) and achieved volitional fatigue. Breath-by-breath measurement was used to determine peak oxygen consumption and to estimate ventilatory threshold. There were no differences in characteristics (age, body mass, height, body mass index, leisure-time physical activity) between the non-HRT and HRT groups, nor were there any differences in responses to maximal exercise, with an observed peak oxygen consumption (mL·kg–1·min–1) of 22.9 ± 3.8 in the non-HRT group and 22.0 ± 4.7 in the HRT group. There was also no difference in submaximal aerobic capacity, with ventilatory threshold values (mL·kg–1·min–1) of 16.7 ± 3.4 in the non-HRT group and 15.6 ± 3.2 in the HRT group. In a sample of healthy moderately active postmenopausal women, there was no difference in maximal or submaximal aerobic fitness parameters beteen the HRT and non-HRT groups.

Seeking the Good Fitting Procedure of PALS Polymer Spectra

2008 ◽  
Vol 607 ◽  
pp. 64-66
Author(s):  
Nicolas Laforest ◽  
Jérémie De Baerdemaeker ◽  
Corine Bas ◽  
Charles Dauwe
Keyword(s):  
Experimental Data ◽  
Low Temperature ◽  
Positron Annihilation ◽  
Physical Meaning ◽  
Lifetime Measurements ◽  
Positron Annihilation Lifetime ◽  
Fitting Procedure ◽  
Fitting Procedures ◽  
Blob Model

Positron annihilation lifetime measurements on polymethylmethacrylate (PMMA) at low temperature were performed. Different discrete fitting procedures have been used to analyze the experimental data. It shows that the extracted parameters depend strongly on the fitting procedure. The physical meaning of the results is discussed. The blob model seems to give the best annihilation parameters.

Robust sideslip angle observer of commercial vehicles based on cornering stiffness estimation using neural network

2022 ◽  
pp. 095440702110724
Author(s):  
Chenyu Zhou ◽  
Liangyao Yu ◽  
Yong Li ◽  
Jian Song
Keyword(s):  
Neural Network ◽  
Mathematical Model ◽  
Stability Control ◽  
Estimation Accuracy ◽  
Accurate Estimation ◽  
Commercial Vehicles ◽  
Sideslip Angle ◽  
The Neural Network ◽  
Wide Range ◽  
The Mathematical Model

Accurate estimation of sideslip angle is essential for vehicle stability control. For commercial vehicles, the estimation of sideslip angle is challenging due to severe load transfer and tire nonlinearity. This paper presents a robust sideslip angle observer of commercial vehicles based on identification of tire cornering stiffness. Since tire cornering stiffness of commercial vehicles is greatly affected by tire force and road adhesion coefficient, it cannot be treated as a constant. To estimate the cornering stiffness in real time, the neural network model constructed by Levenberg-Marquardt backpropagation (LMBP) algorithm is employed. LMBP is a fast convergent supervised learning algorithm, which combines the steepest descent method and gauss-newton method, and is widely used in system parameter estimation. LMBP does not rely on the mathematical model of the actual system when building the neural network. Therefore, when the mathematical model is difficult to establish, LMBP can play a very good role. Considering the complexity of tire modeling, this study adopted LMBP algorithm to estimate tire cornering stiffness, which have simplified the tire model and improved the estimation accuracy. Combined with neural network, A time-varying Kalman filter (TVKF) is designed to observe the sideslip angle of commercial vehicles. To validate the feasibility of the proposed estimation algorithm, multiple driving maneuvers under different road surface friction have been carried out. The test results show that the proposed method has better accuracy than the existing algorithm, and it’s robust over a wide range of driving conditions.

scholarly journals Effect of 9 weeks continuous vs. interval aerobic training on plasma BDNF levels, aerobic fitness, cognitive capacity and quality of life among seniors with mild to moderate Alzheimer’s disease: a randomized controlled trial

2020 ◽  
Vol 17 (1) ◽  
Author(s):  
Lievyn Enette ◽  
Thomas Vogel ◽  
Sylvie Merle ◽  
Anna-Gaelle Valard-Guiguet ◽  
Nathalie Ozier-Lafontaine ◽  
...  
Keyword(s):  
Quality Of Life ◽  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Cognitive Performance ◽  
Aerobic Fitness ◽  
Aerobic Training ◽  
Bdnf Level ◽  
Fitness Parameters ◽  
Functional Capacities

Abstract Background Evidence suggests that aerobic-type training confers physical benefits and appears to contribute positively to brain health. This study aims to compare the effect of 9-weeks continuous (CAT) to interval aerobic training (IAT) on brain derived neurotrophic factor (BDNF) plasma level, aerobic fitness, cognitive performance, and quality of life among senior with Alzheimer’s disease (AD). Methods 52 participants were randomly allocated into three groups (CAT n = 14; IAT n = 17; and Controls n = 21). CAT and IAT consisted of 18 sessions of 30-min cycling, twice a week, over 9 weeks. During the same period, controls were engaged in interactive information sessions. Plasma BDNF level; aerobic fitness parameters (Metabolic equivalent task - METs; Maximal Tolerated Power – MTP); functional capacities (6-Minute Walk Test - 6MWT); cognitive performance (Mini Mental State Examination; Rey auditory verbal learning test; and digit span test) and quality of life (Quality Of Life of Alzheimer’s Disease scale - QoL-AD) were measured in all participants at baseline and 9 weeks later. A third plasma BDNF level was quantified following a 4 weeks detraining. Results No significant change was measured in terms of plasma BDNF level and cognitive performance after interventions, in all groups compared to baseline. After 9 weeks, CAT and IAT significantly improved aerobic fitness parameters compared to controls (METs: + 0.6 and + 1.0 vs. + 0.4; MTP: + 16 watts and + 20 watts vs. + 10 watts; and functional capacities (6MWT: + 22 m and + 31 m vs. -40 m). Compared to controls, QoL-AD after CAT was improved (+ 2 points; p = 0.02). Conclusions Neither aerobic exercise modalities significantly modified plasma BDNF levels and cognitive performances. CAT and IAT enhanced aerobic fitness and functional capacities in AD patients and CAT their QoL. Trial registration ClinicalTrials.gov website (NCT02968875); registration date: 7 September 2016. “Retrospectively registered”.

Cost Analysis and Fuzzy Control for Collapsible Container Usage Based on Closed-Loop Supply Chain Model

2017 ◽  
Vol 139 (8) ◽  
Author(s):  
Xinyan Ou ◽  
Jorge Arinez ◽  
Qing Chang ◽  
Guoxian Xiao
Keyword(s):  
Mathematical Model ◽  
Fuzzy Control ◽  
Closed Loop ◽  
Control Method ◽  
Fuzzy Controller ◽  
Accurate Estimation ◽  
Chain Model ◽  
Market Demand ◽  
Total Cost ◽  
Logistic Cost

In the last decade, global competition has forced manufacturers to optimize logistics. The implementation of collapsible containers provides a new perspective for logistics cost savings, since using collapsible containers reduces the frequency of shipping freight. However, optimization of logistic cost is complicated due to the interactions in a system, such as market demand, inventory, production throughput, and uncertainty. Therefore, a systematic model and accurate estimation of the total cost and system performance are of great importance for decision making. In this paper, a mathematical model is developed to describe deterministic and stochastic scenarios for a closed-loop container dynamic flow system. The uncertainties in a factory and a supplier are considered in the model. The performance evaluation of the collapsible container system and total cost estimation are provided through model analysis. Furthermore, fuzzy control method is proposed to monitor the processing rate of the supplier and the factory and to adjust the rate of the supplier operation then further reduce the logistic cost. A case study with a matlab simulation is presented to illustrate the accuracy of the mathematical model and the effectiveness of the fuzzy controller.

Seasonal changes in wildland firefighter fitness and body composition

2020 ◽  
Vol 29 (3) ◽  
pp. 294
Author(s):  
Steven E. Gaskill ◽  
Charles L. Dumke ◽  
Charles G. Palmer ◽  
Brent C. Ruby ◽  
Joseph W. Domitrovich ◽  
...  
Keyword(s):  
Body Composition ◽  
Aerobic Fitness ◽  
Ventilatory Threshold ◽  
Wildland Fire ◽  
Fire Suppression ◽  
Metabolic Cost ◽  
Load Carriage ◽  
Fat Free Mass ◽  
Fire Season ◽  
Exercise Treadmill

Hiking with a pack is the highest-intensity task that wildland firefighters (WLFFs) perform during sustained activities related to wildland fire suppression. Firefighters perform this and other tasks together as a crew; this provides a unique model to evaluate select physical and physiological changes in members of working crews over a fire season during extended operations. The objective of this study was to evaluate changes in peak aerobic fitness (VO2peak), sustainable aerobic fitness at the ventilatory threshold (VO2vt) and body composition over a 5-month wildland fire season. WLFFs from four crews (55 males, 10 females) participated in a maximal graded exercise treadmill test and body composition evaluation pre- and post season. VO2peak values and variance did not change across the fire season (pre=3.96±0.65, post=3.96±0.69Lmin−1, not significant). VO2vt average decreased slightly while variance decreased greatly within each crew (pre=37.5±7.0, post=35.4±2.3mLkg−1 min−1, P&lt;0.05). There was an improvement in VO2vt in initially less-fit WLFFs and a VO2vt decrease in initially more-fit WLFFs. WLFFs lost fat mass (−1.56±−1.06kg, P&lt;0.01) and fat-free mass (−0.38±−1.24kg, P&lt;0.05). Post-season VO2vt values were the same as the higher range of the documented metabolic cost of uphill load carriage and reveal a unique group adaptation to extended physical demands.

Relationship Between Aerobic Fitness Parameters, Body Temperature and Perceptual Responses Following a Warm-Weather Road Race

2014 ◽  
Vol 46 ◽  
pp. 183
Author(s):  
Luke N. Belval ◽  
Robert A. Huggins ◽  
Douglas J. Casa ◽  
Rebecca L. Stearns ◽  
Deanna M. Dempsey ◽  
...  
Keyword(s):  
Body Temperature ◽  
Aerobic Fitness ◽  
Warm Weather ◽  
Fitness Parameters ◽  
Road Race

V̇o2, V̇co2, and RQ in a respiratory chamber: accurate estimation based on a new mathematical model using the Kalman-Bucy method

2004 ◽  
Vol 96 (3) ◽  
pp. 1045-1054 ◽  
Author(s):  
L. Granato ◽  
A. Brandes ◽  
C. Bruni ◽  
A. V. Greco ◽  
G. Mingrone
Keyword(s):  
Mathematical Model ◽  
Measurement Errors ◽  
Estimation Method ◽  
Accurate Estimation ◽  
Production Rates ◽  
Estimation Errors ◽  
Respiratory Chamber ◽  
Residual Noise ◽  
Proposed Model

A respiratory chamber is used for monitoring O2 consumption (V̇o2), CO2 production (V̇co2), and respiratory quotient (RQ) in humans, enabling long term (24-h) observation under free-living conditions. Computation of V̇o2 and V̇co2 is currently done by inversion of a mass balance equation, with no consideration of measurement errors and other uncertainties. To improve the accuracy of the results, a new mathematical model is suggested in the present study explicitly accounting for the presence of such uncertainties and error sources and enabling the use of optimal filtering methods. Experiments have been realized, injecting known gas quantities and estimating them using the proposed mathematical model and the Kalman-Bucy (KB) estimation method. The estimates obtained reproduce the known production rates much better than standard methods; in particular, the mean error when fitting the known production rates is 15.6 ± 0.9 vs. 186 ± 36 ml/min obtained using a conventional method. Experiments with 11 humans were carried out as well, where V̇o2 and V̇co2 were estimated. The variance of the estimation errors, produced by the KB method, appears relatively small and rapidly convergent. Spectral analysis is performed to assess the residual noise content in the estimates, revealing large improvement: 2.9 ± 0.8 vs. 3,440 ± 824 (ml/min)2 and 1.8 ± 0.5 vs. 2,057 ± 532 (ml/min)2, respectively, for V̇o2 and V̇co2 estimates. Consequently, the accuracy of the computed RQ is also highly improved (0.3 × 10-4 vs. 800 × 10-4). The presented study demonstrates the validity of the proposed model and the improvement in the results when using a KB estimation method to resolve it.

MODELLING THE INTERACTION BETWEEN RAILWAY WHEEL AND RAIL

Transport ◽  
2008 ◽  
Vol 23 (3) ◽  
pp. 236-239 ◽  
Author(s):  
Stasys Dailydka ◽  
Leonas Povilas Lingaitis ◽  
Sergey Myamlin ◽  
Vladimir Prichodko
Keyword(s):  
Mathematical Model ◽  
Operating Conditions ◽  
Rolling Stock ◽  
Dynamic Processes ◽  
Running Speed ◽  
Railway Wheel ◽  
The Real ◽  
The Impact ◽  
Railway Rolling Stock

The article presents a mathematical model for assessing the real operating conditions of railway rolling stock, taking into account the situations when the wheel loses contact with rail. The obtained amplitudinal fluctuation characteristics depend on the set roughness function and the running speed of the wheel. When calculating dynamic processes, the contact between wheel and rail should be considered unstable. With the increase of speed, the impact of this instability increases.

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