scholarly journals Gender-Related Differences in Mechanics of the Sprint Start and Sprint Acceleration of Top National-Level Sprinters

2020 ◽  
Vol 17 (18) ◽  
pp. 6447
Author(s):  
Dragan M. Mirkov ◽  
Olivera M. Knezevic ◽  
Amador Garcia-Ramos ◽  
Milan Čoh ◽  
Nejc Šarabon
Keyword(s):  
National Level ◽  
Accurate Information ◽  
Maximal Velocity ◽  
Time Data ◽  
Maximal Force ◽  
Acceleration Force ◽  
Laser Distance Sensor ◽  
Force Velocity ◽  
The Relationship ◽  
Kinematics And Kinetics

(1) Background: Within the current study we aimed at exploring gender-related differences and the relationship between sprint start block kinematics and kinetics and sprint acceleration force–velocity (F-v) relationship parameters (maximal force [F0], maximal velocity [v0], maximal power [Pmax] and slope) in top national-level sprinters. (2) Methods: Twenty-eight sprinters (6 females) performed 10 maximal 30-m sprints. Start block and acceleration kinematics and kinetics were collected with an instrumented sprint start block and a laser distance sensor (KiSprint system). Displacement-time data were used to determine the F-v relationship through Samozino’s method. (3) Results: Start block rear foot maximal force (effect size [ES] = 1.08), rate of force development (ES = 0.90–1.33), F0 (ES = 1.38), v0 (ES = 1.83) and Pmax (ES = 1.95) were higher in males than in females (p ≤ 0.05). There were no differences in the slope, and ratio of horizontal-to-resultant force. F0, v0, and Pmax generally presented higher correlations with the start block kinetics (median r [range] = 0.49 [0.28, 0.78]) than with the kinematics (median r [range] = −0.27 [−0.52, 0.28]). (4) Conclusions: We confirmed that sprint block phase and sprint acceleration mechanics should be mutually assessed when analyzing sprinting performance. KiSprint system could provide more accurate information regarding mechanical pattern and technique during sprint initiation and acceleration, and potentially help create a more personalized and effective training program.

scholarly journals Comparison of two measurement devices for obtaining horizontal force-velocity profile variables during sprint running

2022 ◽  
pp. 174795412110672
Author(s):  
Erin Feser ◽  
Kyle Lindley ◽  
Kenneth Clark ◽  
Neil Bezodis ◽  
Christian Korfist ◽  
...  
Keyword(s):  
Random Error ◽  
Maximum Velocity ◽  
American Football ◽  
Systematic Bias ◽  
Maximal Velocity ◽  
Horizontal Force ◽  
Time Data ◽  
Measured Velocity ◽  
Theoretical Maximum ◽  
Force Velocity

This study established the magnitude of systematic bias and random error of horizontal force-velocity (F-v) profile variables obtained from a 1080 Sprint compared to that obtained from a Stalker ATS II radar device. Twenty high-school athletes from an American football training group completed a 30 m sprint while the two devices simultaneously measured velocity-time data. The velocity-time data were modelled by an exponential equation fitting process and then used to calculate individual F-v profiles and related variables (theoretical maximum velocity, theoretical maximum horizontal force, slope of the linear F-v profile, peak power, time constant tau, and horizontal maximal velocity). The devices were compared by determining the systematic bias and the 95% limits of agreement (random error) for all variables, both of which were expressed as percentages of the mean radar value. All bias values were within 6.32%, with the 1080 Sprint reporting higher values for tau, horizontal maximal velocity, and theoretical maximum velocity. Random error was lowest for velocity-based variables but exceeded 7% for all others, with slope of the F-v profile being greatest at ±12.3%. These results provide practitioners with the information necessary to determine if the agreement between the devices and the magnitude of random error is acceptable within the context of their specific application.

Ontogeny of shortening velocity in porcine trachealis

1992 ◽  
Vol 262 (3) ◽  
pp. L280-L285 ◽  
Author(s):  
K. Ikeda ◽  
R. W. Mitchell ◽  
K. A. Guest ◽  
C. Y. Seow ◽  
C. F. Kirchhoff ◽  
...  
Keyword(s):  
Isometric Force ◽  
Electrical Field Stimulation ◽  
Contractile Force ◽  
Postnatal Life ◽  
Maximal Velocity ◽  
Shortening Velocity ◽  
Lever System ◽  
Velocity Of Shortening ◽  
Force Velocity ◽  
The Relationship

We examined the effect of maturation on force-velocity (F-V) parameters in porcine tracheal smooth muscle (TSM) to determine the relationship between maximal isometric contractile force (Po) and maximal velocity of shortening (Vmax). Strips of TSM excised from 1-day-old neonatal swine (neo; n = 8), 2-wk-old swine (2ws; n = 7), and 10-wk-old swine (10ws; n = 7) were tethered to an electromagnetic lever system for F-V analysis of contractility. TSM strips were activated by electrical field stimulation at optimal resting tension, voltage, and length (Lo) so that maximal reproducible contractile force (Po) was elicited. Velocities were measured at the early phase of isometric contraction (3.1 +/- 0.1 s for neo, 2.9 +/- 0.1 s for 2ws, and 3.1 +/- 0.1 s for 10ws; P = NS). Shortening velocity increased progressively with maturation; Vmax was 0.164 +/- 0.011 Lo/s for neo, 0.194 +/- 0.013 Lo/s for 2ws (P less than 0.05 vs. neo), and 0.260 +/- 0.024 Lo/s for 10ws (P less than 0.01 vs. neo; P less than 0.05 vs. 2ws). Maximal isometric force generation increased substantially during the first 2 wk of postnatal life and thereafter returned to neonatal levels; Po was 71.5 +/- 2.1 mN/mm2 for neo, 95.4 +/- 7.0 mN/mm2 for 2ws, and 74.7 +/- 6.2 mN/mm2 for 10ws (P less than 0.05, 2ws vs. neo and 10ws). In separate studies, we also determined whether differences in Vmax occurred during the normal cycling phase of the cross bridge (3 s) or during the slowly cycling phase of the latch bridge (8 s) in tissue from 12 additional animals.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Kinematics and Kinetics of Bulgarian-Bag-Overloaded Sprints in Young Athletes

Life ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 282
Author(s):  
Marco Duca ◽  
Athos Trecroci ◽  
Enrico Perri ◽  
Damiano Formenti ◽  
Giampietro Alberti
Keyword(s):  
Peak Power ◽  
Power Production ◽  
Maximal Velocity ◽  
Sprint Training ◽  
Young Athletes ◽  
Production Methods ◽  
Velocity Relationship ◽  
Force Velocity ◽  
Kinetics Of ◽  
Kinematics And Kinetics

Background: Effective sprinting requires large acceleration capabilities. To accelerate, large amount of force must be produced and applied effectively. The use of different implements such as sleds and vests can increase the amount of force produced and alter sprinting effectiveness. We propose the use of increasing overload via the Bulgarian Bag (BB) as a means to modify athletes’ sprint and acutely increase force and power production. Methods: 24 young athletes performed three sprints over 20 m in three different conditions: unloaded (BW) and loaded with BB weighing 2.5% (BB2.5) and 5% (BB5) of the athlete’s body mass. Sprint times at 2.5, 5, 10, 15, and 20 m were acquired and used to compute the force–velocity relationship for the sprints. Maximal velocity (V0), peak force (F0), peak power (PP), and decrease in ratio of force (DRF) were computed. Results: the additional load caused a decrease in sprint times (p < 0.05) and V0 (p = 0.028), conversely no differences were found for F0 (p = 0.21), PP (p = 0.50), and DRF (p = 0.83). Conclusions: Based on those findings, BB can be an alternative method to effectively overload sprint training toward improving sprinting performance.

scholarly journals The force-velocity profile as determinant of spike and serve ball speed in top-level male volleyball players

PLoS ONE ◽  
2021 ◽  
Vol 16 (4) ◽  
pp. e0249612
Author(s):  
Andrés Baena-Raya ◽  
Alberto Soriano-Maldonado ◽  
Manuel A. Rodríguez-Pérez ◽  
Antonio García-de-Alcaraz ◽  
Manuel Ortega-Becerra ◽  
...  
Keyword(s):  
Bench Press ◽  
Training Programs ◽  
Practical Interest ◽  
Maximal Velocity ◽  
Strength And Conditioning ◽  
Ball Speed ◽  
Vertical Jumping ◽  
Volleyball Players ◽  
Force Velocity ◽  
The Relationship

Understanding the relationship between mechanical variables derived from actions such as jumping, sprinting, or ballistic bench press throwing and sport-specific performance moves is of scientific and practical interest for strength and conditioning coaches for improving training programs. We examined the association between mechanical variables derived from the force-velocity (FV) profiles of the aforementioned actions and spike and serve ball speeds in elite volleyball players. Twenty-two male elite volleyball players (age: 24.3 ± 4.5 years; height: 1.89 ± 0.06 m; body mass: 86.3 ± 8.6 kg) were tested in two sessions. Squatting, sprinting, and bench press throwing FV profiles were determined in the first session, while spike and serve ball speeds were assessed in the second session. The theoretical maximal force (F0) of vertical jumping, the theoretical maximal velocity of sprinting, and the F0 of bench press throwing in ascending order, were strongly associated (rs range 0.53–0.84; p<0.05) with spike and serve ball speeds. These mechanical variables explained 20%-36% of the variability in spike and serve ball speeds, with a greater influence on the serve speed. These results suggest that assessing jumping, sprinting, and bench press throwing force-velocity profiles might help provide player-specific training programs and optimize performance in these technical-tactical actions in male elite volleyball players.

EVALUATION OF THE MAXIMAL THEORETICAL FORCE EXERTED BY THE LEGS, WITH AN ISOTONIC LEG EXTENSION MACHINE

2005 ◽  
Vol 05 (04) ◽  
pp. 549-554 ◽  
Author(s):  
IVAN CORAZZA ◽  
ELENA CAROLI ◽  
SEBASTIANO ZANNOLI ◽  
ROMANO ZANNOLI ◽  
PASQUALINO MAIETTA LATESSA ◽  
...  
Keyword(s):  
Sports Medicine ◽  
Maximal Velocity ◽  
Error Level ◽  
Acceptable Error ◽  
Leg Extension ◽  
Maximal Force ◽  
Linear Behavior ◽  
The Right ◽  
The Relationship ◽  
And Training

Evaluating the maximal force exertable by a subject in a particular exercise is an important starting step in setting up rehabilitation and training programs. The current reference procedure is the isokinetic approach, which has some limitations due to poor physiological agreement and high cost of the equipment. This paper describes a method for evaluating maximal force using an isotonic approach. The maximal force value is extrapolated from the linear behavior of the relationship between the force and the maximal velocity at lower loads. The method was applied to a group of 25 students at the Sports Medicine Faculty, University of Bologna using a leg extension AirMachine (919 Tech). Loads were settled adopting a step-up protocol and the maximal velocity was calculated by measuring the instantaneous angle of the lever. The linear correlation coefficient between the settled loads and the maximal velocity ranged between 0.5679 and 0.9980 for the right leg and between 0.6791 and 0.9895 for the left leg, and the maximal estimated force ranged between 26.9 kg and 248.2 kg for the right leg and between 32.6 kg and 221.9 kg for the left leg. The method showed a good feasibility and an acceptable error level, and can be proposed as an alternative to the isokinetic approach.

Ozone Concentration Prediction using Artificial Neural Networks

2017 ◽  
Vol 68 (10) ◽  
pp. 2224-2227 ◽  
Author(s):  
Camelia Gavrila
Keyword(s):  
Neural Networks ◽  
Artificial Neural Networks ◽  
Ozone Concentration ◽  
Meteorological Data ◽  
Global Solar Radiation ◽  
Time Data ◽  
Marquardt Algorithm ◽  
Sensitivity Tests ◽  
Artificial Neural ◽  
The Relationship

The aim of this paper is to determine a mathematical model which establishes the relationship between ozone levels together with other meteorological data and air quality. The model is valid for any season and for any area and is based on real-time data measured in Bucharest and its surroundings. This study is based on research using artificial neural networks to model nonlinear relationships between the concentration of immission of ozone and the meteorological factors: relative humidity (RH), global solar radiation (SR), air temperature (TEMP). The ozone concentration depends on following primary pollutants: nitrogen oxides (NO, NO2), carbon monoxide (CO). To achieve this, the Levenberg-Marquardt algorithm was implemented in Scilab, a numerical computation software. Performed sensitivity tests proved the robustness of the model and its applicability in predicting the ozone on short-term.

scholarly journals Deservingness for "Family 500 +" Benefit in Poland: Qualitative Study of Internet Debates

2021 ◽  
Author(s):  
Piotr Michoń
Keyword(s):  
Future Research ◽  
Online Forums ◽  
Time Data ◽  
Social Surveys ◽  
Cash Benefit ◽  
Internet Forums ◽  
Welfare Attitudes ◽  
New Criterion ◽  
First Time ◽  
The Relationship

AbstractThe need for qualitative research of deservingness perception is strongly emphasised in the literature. This article studies the perception of deservingness for a "Family 500 +"—cash benefit in Poland. For the first time, data from online forums was used in the studies of deservingness and welfare attitudes. It allowed to avoid numerous limitations associated with social surveys. The qualitative analysis showed how participants of Internet debates perceive the criteria of deservingness: control, attitude, reciprocity, identity, need, and what are the relations between the criteria. The impurity of all deservingness criteria was indicated and a new criterion “adequacy” was proposed. Moreover due to the fact that the study concerned a concrete, non-abstract family cash benefit addressed the relationship between the perceived deservingness of children and their parents was pointed out. The vast majority of posts on Internet forums referred to deservingness of parents, not children. This is particularly evident in relation to the criteria of control and reciprocity. Presenting the hypothesis of jealousy and scapegoat strategy, the article also shows the direction of future research on deservingness.

scholarly journals Investigating the Links between UK House Prices and Share Prices with Copulas

2021 ◽  
Author(s):  
Rakesh K. Bissoondeeal ◽  
Leonidas Tsiaras
Keyword(s):  
Stock Market ◽  
House Prices ◽  
National Level ◽  
Tail Dependence ◽  
Share Prices ◽  
Property Prices ◽  
Left Tail ◽  
The Uk ◽  
The Relationship ◽  
Shared Characteristic

AbstractWe investigate the nonlinear links between the housing and stock markets in the UK using copulas. Our empirical analysis is conducted at both the national and regional levels. We also examine how closely London house prices are linked to those in other parts of the UK. We find that (i) the dependence between the different markets exhibits significant time-variation, (ii) at the national level, the relationship between house prices and the stock market is characterised by left tail dependence, i.e., they are more likely to crash, rather than boom, together, (iii) although left tail dependence with the stock market is a prominent feature of some regions, it is by no means a universally shared characteristic, (iv) the dependence between property prices in London and other parts of the UK displays widespread regional variations.

The Relationship Between Genotype and Positive Psychological Development in National-Level Swimmers

2006 ◽  
Vol 11 (2) ◽  
pp. 143-148 ◽  
Author(s):  
Jim Golby ◽  
Michael Sheard
Keyword(s):  
National Level ◽  
Psychological Theory ◽  
Self Esteem ◽  
Psychological Development ◽  
Mental Toughness ◽  
Positive Affectivity ◽  
Buccal Swabs ◽  
Preliminary Study ◽  
The Relationship ◽  
Psychological Questionnaires

We report a preliminary study of the relationship between genotype (using a functional polymorphism of the serotonin transporter 5-HTT gene) and positive psychological development in high-achieving adolescent swimmers. Thirty-one volunteers of both genders, aged 10-24 years, completed a battery of positive psychological questionnaires measuring hardiness, mental toughness, self-esteem, self-efficacy, dispositional optimism, and positive affectivity. DNA samples were obtained via buccal swabs. The sample was initially split into three groups on the basis of 5-HTT genotype: SS, SL, and LL. Multivariate statistics revealed a discernible trend of a relationship between LL genotype and higher levels of positive psychological development. The nonsignificant overall effect is interpreted in terms of sample size and age of participants. The implications of these results are discussed relative to previous findings and in terms of psychological theory.

Comparative force-velocity relation and analyses of myosin of dog atria and ventricles

1982 ◽  
Vol 243 (3) ◽  
pp. H391-H397 ◽  
Author(s):  
J. Wikman-Coffelt ◽  
H. Refsum ◽  
G. Hollosi ◽  
L. Rouleau ◽  
L. Chuck ◽  
...  
Keyword(s):  
Atpase Activity ◽  
Calcium Concentration ◽  
Maximum Velocity ◽  
Calcium Sensitivity ◽  
Myofibrillar Proteins ◽  
Maximal Velocity ◽  
Velocity Of Shortening ◽  
Force Velocity ◽  
Normal Calcium ◽  
Actin Concentration

The isolated muscle and purified myofibrillar proteins of canine atria and ventricles were compared relative to force-velocity relations and rate of adenosine 5'-triphosphatase (ATPase) activity as a function of calcium concentrations. The maximal stress development of isolated trabeculae of canine atria was similar to that of canine right ventricular papillary muscles when analyzed at saturating calcium concentrations (7.5 mM); however, stress was less in the atria when studied at normal calcium concentrations (2.5 mM). The maximal velocity of shortening of atrial trabeculae was about 2.3 times higher than that of ventricular muscle. Regulated actomyosin characterized from the myofibrillar proteins of the two tissues gave directionally similar calcium sensitivity. The maximum velocity of shortening for actin-activated atrial myosin of the dog was approximately 1.8 times higher when the latter was analyzed as a function of actin concentration. Both maximal tension of isolated muscle and regulated actomyosin ATPase activity were dependent on calcium concentration.

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