Assessment of professional Argentine football players using the UNCa test

Objective: To evaluate the maximum oxygen consumption (VO2max) and the Maximum Aerobic Speed (MAS) with direct and portable measurement in field, in professional soccer players using the UNCa test. Material and method: 9 professional soccer players (age: 26.8±5.12 years, mass: 78.7±5.8 kg, height: 177.3±5.8 cm), belonging to the first and promotion categories of AFA soccer league, were measured in the field with the UNCa test using direct gas measurement. A subsample of 3 players was also measured on treadmill. On treadmill and in the field, the same Medgraphics® VO2000 gas analyzer was used. Results: In the field, a VO2max of 52.18±5.86 ml/kg/min, and a MAS of 14.8±1.3 km/h were found. Also, a correlation between VO2max and MAS of r = 0.75, and between MAS and the final speed reached (FSR) r=0.91. In the subsample, no differences were found between treadmill and field in VO2max; 46.6±1.4 ml/kg/min and 48.1±2.2 ml/kg/min (p <0.001) respectively. Differences between MAS are shown; 17.0±0.0 km/h for the treadmill and 13.7±1.5 km/h for the field (p <0.001) replicating the protocol. Conclusion: If professional players of the Argentine Football Association (AFA) were measured directly and in the field, applying the UNCa test for the first time. The VO2max and MAS values were slightly lower than those published in the bibliography

Estimated Artificial Neural Network Modeling of Maximal Oxygen Uptake Based on Multistage 10-m Shuttle Run Test in Healthy Adults

We aimed to develop an artificial neural network (ANN) model to estimate the maximal oxygen uptake (VO2max) based on a multistage 10 m shuttle run test (SRT) in healthy adults. For ANN-based VO2max estimation, 118 healthy Korean adults (59 men and 59 women) in their twenties and fifties (38.3 ± 11.8 years, men aged 37.8 ± 12.1 years, and women aged 38.8 ± 11.6 years) participated in this study; data included age, sex, blood pressure (systolic blood pressure (SBP), diastolic blood pressure (DBP)), waist circumference, hip circumference, waist-to-hip ratio (WHR), body composition (weight, height, body mass index (BMI), percent skeletal muscle, and percent body), 10 m SRT parameters (number of round trips and final speed), and VO2max by graded exercise test (GXT) using a treadmill. The best estimation results (R2 = 0.8206, adjusted R2 = 0.7010, root mean square error; RMSE = 3.1301) were obtained in case 3 (using age, sex, height, weight, BMI, waist circumference, hip circumference, WHR, SBP, DBP, number of round trips in 10 m SRT, and final speed in 10 m SRT), while the worst results (R2 = 0.7765, adjusted R2 = 0.7206, RMSE = 3.494) were obtained for case 1 (using age, sex, height, weight, BMI, number of round trips in 10 m SRT, and final speed in 10 m SRT). The estimation results of case 2 (using age, sex, height, weight, BMI, waist circumference, hip circumference, WHR, number of round trips in 10 m SRT, and final speed in 10 m SRT) were lower (R2 = 0.7909, adjusted R2 = 0.7072, RMSE = 3.3798) than those of case 3 and higher than those of case 1. However, all cases showed high performance (R2) in the estimation results. This brief report developed an ANN-based estimation model to predict the VO2max of healthy adults, and the model’s performance was confirmed to be excellent.

Simulation of a Motor Vehicle Momentarily Accelerating in Various Road Conditions

In this paper some selected conclusions have been drawn from the simulated maneuver of a vehicle’s momentary acceleration in various road conditions. The aim of this paper was to answer the question whether the random irregularities of the road could decrease the final speed of the vehicle and cause it to deviate from the straight line motion and to what extent. These irregularities had three different maximum amplitudes which enabled analysis of vehicle’s acceleration on the less and the more uneven road. Also, almost the same and almost different profiles were assumed for the left and the right wheels of the vehicle’s model. Some additional phenomena such as the ice on the road have been taken into account. The initial speed was 20 km/h and after 2 s the vehicle started to accelerate. Then, after 8 s the simulation stopped, which gave the whole simulation time equal to 10 s.

Synthesis of the Additive Terminal Control of Uniaxial Motion of Nonlinear Objects

A method for synthesizing the laws of terminal control of uniaxial movement of nonlinear dynamic objects is proposed. The problem is solved for the case when the control action is included in the scalar additive component of the nonlinear equations of the object. Target control laws meet the requirement to transfer an object from an arbitrary initial state toa specified final position with a specified final speed. The other parameters of the object’s state at the end time are generally not controlled. When assigning a zero final speed, the object’s "soft" transition to the specified position is achieved, which is necessary for many terminal systems. Due to the fundamental complexity of optimal synthesis in conditions where the control object has nonlinear properties, a purely terminal formulation of the problem is preferable. One of the most effective means of solving this problem is the methods of trajectory planning and solving inverse dynamics problems. This approach is adopted in this study. Using it together with additional analysis allowed us to write the control law in the feedback form for the case of a nonlinear mathematical model of the object. The developed synthesis method is characterized by simplicity of form and ease of practical implementation, for example, using embedded microcontrollers. Known general approaches are usually associated with a significant expenditure of time and technical resources of the control system in this case. The specified efficiency of the method is achieved by taking into account the features of scalar and additive control in the system. The use of the method is illustrated by an example of "soft" turn of the sequential excitation electric motor shaft at a given angle with zero final speed, which does not require the use of rigid stop. The latter circumstance means a significant improvement in the quality of terminal control. Under this condition, the organization of positioning of mobile executive bodies of various industrial equipment is significantly simplified.

The importance of aerobic fitness for tennis: training and testing (part 2)

In part 1 of this series we discussed why aerobic fitness is important for tennis players (Genevois, 2019). Scientific studies have revealed that High Intensity Intermittent Training (HIIT) is an efficient way to improve aerobic fitness either off- or on-court, depending on the training phase. The intensity of the training sessions can be individualized based on the final speed reached during the 30/15 Intermittent Fitness Test.

ИССЛЕДОВАНИЕ ВЫГРУЗКИ ТРАНСПОРТНЫХ СРЕДСТВ ПРИ УБОРКЕ КАРТОФЕЛЯ

Уборка картофеля предполагает транспортировку клубней с поля до хранилищ. Транспортные средства для перевозки картофеля весьма разнообразны и разнотипны это и автомашинысамосвалы, тракторные самосвальные прицепы, автомашины с полуприцепами и контейнеровозы. В большинстве картофелеводческих хозяйств площади, занятые под картофель, не превышают 300 га, а для транспортировки урожая применяют большегрузные самосвалы. Выгрузка картофеля из кузова происходит в результате подъемаопрокидывания, что приводит к образованию гравитационных потоков клубней и способствует появлению механических повреждений клубней. Взаимодействия клубней при выгрузке генерируют напряжения в насыпи картофеля за счет передачи ударных импульсов. В работе исследуется процесс скатывания одиночных клубней по насыпи картофеля. Анализ движения единичных клубней по насыпи показал, что качение клубня происходит при достаточной силе трения под углом естественного откоса. Наибольшее влияние на кинетическую энергию системы будет оказывать путь, пройдённый клубнем по насыпи чем больше путь, тем больше энергия. Значительную роль будет оказывать также конечная скорость клубня. Снизить кинетическую энергию клубня можно, уменьшая участок разгона с помощью установки дополнительных препятствий в кузове, например, поперечной перегородки. Для уточнения теоретических выкладок был проведен эксперимент по выгрузке клубней из контейнера без перегородки и оборудованного поперечной перегородкой. В ходе эксперимента изучались раскат клубней от контейнера, характеризующий скорость клубней при скатывании по насыпи, и остаток клубней в кузове, характеризующий скорость выгрузки клубней. Установлено, что дополнительные поперечные перегородки способствуют снижению кинетической энергии картофеля при выгрузке и снижают механические повреждения клубней.Harvesting potatoes involves transporting tubers from the field to storage. Vehicles for transporting potatoes are very diverse and diverse these are dump trucks, tractor dump trailers, trucks with semitrailers and container carriers. In most potato farms, the area occupied by potatoes does not exceed 300 hectares, and heavy trucks are used to transport the crop. Unloading of potatoes from the body occurs as a result of lifting tipping, which leads to the formation of gravitational flows of tubers and contributes to the appearance of mechanical damage to tubers. The interactions of the tubers during unloading generate stresses in the embankment of the potato due to the transmission of shock pulses. We investigate the rolling of single tubers over a mound of potatoes. Analysis of the movement of individual tubers along the embankment showed that the tuber rolls with sufficient friction at an angle of repose. the kinetic energy of the system will be most affected by the path traveled by the tuber through the embankment the larger the path, the greater the energy. The final speed of the tuber will also play a significant role. Reducing the kinetic energy of the tuber, it is possible to reduce the acceleration area by installing additional obstacles in the body, for example, a transverse partition. To clarify the theoretical calculations, an experiment was conducted to unload tubers from a container without a partition and equipped with a transverse partition. During the experiment, the tuber roll from the container was studied, which characterizes the speed of the tubers when rolling along the embankment, and the remainder of the tubers in the back, which characterizes the speed of unloading the tubers. Additional transverse partitions have been established that contribute to a decrease in the kinetic energy of potatoes during unloading and reduce mechanical damage to tubers.

The Elevated Track in Pole Vault: An Advantage During Run-Up?

Background: Approach speed is a major determinant of pole-vault performance. Athletic jump events such as long jump, triple jump, and pole vault can utilize an elevated track for the runway. Feedback from athletes indicates a benefit of using an elevated track on their results. However, there is no evidence that elevated tracks increase athletes’ performance. Purpose: To investigate the potential advantage of using an elevated track during elite pole-vault competitions on run-up speed parameters. Methods: Performance and run-up criteria (speed, stride rate, contact, and aerial time) were measured from 20 high-level male pole-vaulters during official competitions on either a regular or an elevated track. Parameters comparisons were made between both conditions, and run-up parameters were confronted to speed modification on the elevated track. Results: Statistical analyses indicated that for the elevated track, there was a small improvement in final speed (1.1%), stride rate (1.1%), and takeoff distance (3.1%) and a small reduction in aerial time (−1.9%). The study highlighted different individual responses depending on athletes’ capabilities. The authors noted that speed improvement was largely correlated with stride-rate improvement (r = .61) and contact-time reduction (r = −.51) for slower athletes. Conclusions: Elevated tracks can increase final approach speed in pole vault and positively influence performance. Interindividual responses were observed in these findings.

The influence of the regression model and final speed criteria on the reliability of lactate threshold determined by the Dmax method in endurance-trained runners

Few studies verified the reliability of the lactate threshold determined by Dmax method (LTDmax) in runners and it remains unclear the effect of the regression model and the final speed on the reliability of LTDmax. This study aimed to examine the test–retest reliability of the speed at LTDmax in runners, considering the effects of the regression models (exponential-plus-constant vs third-order polynomial) and final speed criteria (complete vs proportional). Seventeen male, recreational runners performed 2 identical incremental exercise tests, with increments of 1 km·h–1 each for 3 min on treadmill to determine peak treadmill speed (Vpeak) and lactate threshold. Earlobe capillary blood samples were collected during rest between the stages. The Vpeak was defined as the speed of the last complete stage (complete final speed criterion) and as the speed of the last complete stage added to the fraction of the incomplete stage (proportional final speed criterion). Lactate threshold was determined from exponential-plus-constant and from third-order polynomial regression models with both complete and proportional final speed criteria and from fixed blood lactate level of 3.5 mmol·L−1 (LT3.5mM). The LTDmax obtained from the exponential-plus-constant regression model presented higher reliability (coefficient of variation (CV) ≤ 3.7%) than the LTDmax calculated from the third-order polynomial regression model (CV ≤ 5.8%) and LT3.5mM (CV = 5.4%). The proportional final speed criterion is more appropriate when using the exponential-plus-constant regression model, but less appropriate when using the third-order polynomial regression model. In conclusion, exponential-plus-constant using the proportional final speed criterion is preferred over LT3.5mM and over third-order polynomial regression model to determine a reliable LTDmax.