scholarly journals FORCE-VELOCITY RELATIONSHIP OF LEG EXTENSORS OBTAINED FROM THREE DIFFERENT TYPES OF LOAD

2018 ◽  
Vol 15 (3) ◽  
pp. 467
Author(s):  
Marko Ćosić ◽  
Saša Đurić ◽  
Milena Živković ◽  
Aleksandar Nedeljković
Keyword(s):  
Concurrent Validity ◽  
Isometric Force ◽  
Maximal Velocity ◽  
Muscle System ◽  
Different Types ◽  
Force Velocity ◽  
Muscle Groups ◽  
Leg Extensors ◽  
Relationship Of ◽  
The Impact

The first aim of this study was to evaluate the shape of force-velocity (F-V) relationships in case of gravitational (W), inertial (I) and combined (W+I) type of load assessed from squat jump (SJ) performed on a modified Smith machine. The second aim was to determine whether there were differences between the same parameters (maximal force, F0; maximal velocity, V0; maximal power, P0) obtained from linear F-V relationship among three different loads. The third aim was to evaluate the concurrent validity of the parameters F0 obtained from different types of load in SJ, with maximum isometric force in squat (Fiso), as well as one repetition maximum in squat (1RM). Fifteen male participants were tested in SJ with three different types of load, squat for obtaining 1RM and isometric squat for obtaining the Fiso. The observed F-V relationships were exceptionally strong and approximately linear (median r ≥ 0.98) independently of used load. The differences between same parameters of different types of load were determined in parameters F0 and V0, while there were no differences between P0. Regarding third aim, concurrent validity for F0 showed to be moderate to high and significant in all 3 types of load (r ≥ 0.56), except between F0 and Fiso in W type of load, where it was non-significant (r ≥ 0.47). The significance of the study reflects in better understanding of the mechanisms of the functioning of muscle system in case of different types of load. Future studies should investigate the impact of different types of load to kinetic and kinematic parameters in case of different motoric tasks and muscle groups.

scholarly journals Internet Usage and Academic Achievement of Adolescents of West Bengal: An Exploratory Study

2017 ◽  
Vol 7 (3) ◽  
pp. 270
Author(s):  
Bikram Maiti
Keyword(s):  
Academic Achievement ◽  
Sampling Method ◽  
West Bengal ◽  
Internet Usage ◽  
Different Types ◽  
Negative Effect ◽  
Higher Secondary Education ◽  
Relationship Of ◽  
The Impact ◽  
The Relationship

Present study is a process to find out the effect of internet usage on the academic achievement of adolescents of West Bengal, specifically on the students of Higher Secondary level under the West Bengal Council of Higher Secondary Education. To study the impact thoroughly the investigator divided internet usage into three categories- Educational usage, Communicational usage and Recreational usage. Intending to fetch out the relationship of different types of internet usage with students’ academic achievement as well as the gender difference regarding the internet usage, the researcher formulated some null hypotheses. To go through this study the investigator administered an internet usage questionnaire on 138 class XI students, selected by purposive sampling method from different schools under WBCHSE. Percentage of marks obtained by the adolescents in Madhyamik examination was treated as the academic achievement by them. The investigator used Pearson’s Product Moment Correlation Coefficient and Independent Sample‘t’ test for testing the hypotheses. By the end of the study it was seen that Educational usage and Communicational usage of internet had no effect on their academic achievements, but there was negative effect of Recreational internet usage on their academic achievement. Also, boys and girls differed significantly in respect to their different internet usage.

scholarly journals Is Test Standardization Important when Arm and Leg Muscle Mechanical Properties are Assessed Through the Force‐Velocity Relationship?

2019 ◽  
Vol 69 (1) ◽  
pp. 47-58
Author(s):  
Marko Cosic ◽  
Sasa Djuric ◽  
Milena Z. Zivkovic ◽  
Aleksandar Nedeljkovic ◽  
Bojan Leontijevic ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Concurrent Validity ◽  
Bench Press ◽  
Isometric Force ◽  
Movement Pattern ◽  
Strength Properties ◽  
Maximum Force ◽  
Force Velocity ◽  
Leg Muscle ◽  
Squat Jumps

Abstract The force‐velocity (F‐V) relationship observed in multi‐joint tasks proved to be strong and approximately linear. Recent studies showed that mechanical properties of muscles: force (F), velocity (V) and power (P) could be assessed through the F‐V relationship although the testing methods have not been standardized. The aim of the present study was to evaluate and compare F‐V relationships assessed from two tests performed on a modified Smith machine that standardizes kinematics of the movement pattern. Fifteen participants were tested on the maximum performance bench press throws and squat jumps performed against a variety of different loads. In addition, their strength properties were assessed through maximum isometric force (Fiso) and one repetition maximum (1 RM). The observed individual F‐V relationships were exceptionally strong and approximately linear (r = 0.98 for bench press throws; r = 0.99 for squat jumps). F‐V relationship parameter depicting maximum force (F0) revealed high correlations with both Fiso and 1 RM indicating high concurrent validity (p < 0.01). However, the generalizability of F‐V relationship parameters depicting maximum force (F0), velocity (V0) and power (P0) of the tested muscle groups was inconsistent and on average low (i.e. F0; r = ‐0.24) to moderate (i.e. V0 and P0; r = 0.54 and r = 0.64, respectively; both p < 0.05). We concluded that the F‐V relationship could be used for the assessment of arm and leg muscle mechanical properties when standard tests are applied, since the typical outcome is an exceptionally strong and linear F‐V relationship, as well as high concurrent validity of its parameters. However, muscle mechanical properties could be only partially generalized across different tests and muscles.

scholarly journals Force–velocity relationship of leg extensors obtained from loaded and unloaded vertical jumps

2014 ◽  
Vol 114 (8) ◽  
pp. 1703-1714 ◽  
Author(s):  
Ivan Cuk ◽  
Milos Markovic ◽  
Aleksandar Nedeljkovic ◽  
Dusan Ugarkovic ◽  
Milos Kukolj ◽  
...  
Keyword(s):  
Velocity Relationship ◽  
Force Velocity ◽  
Leg Extensors ◽  
Relationship Of ◽  
Vertical Jumps

Loaded Vertical Jumping: Force–Velocity Relationship, Work, and Power

2016 ◽  
Vol 32 (2) ◽  
pp. 120-127 ◽  
Author(s):  
Daniel Feeney ◽  
Steven J. Stanhope ◽  
Thomas W. Kaminski ◽  
Anthony Machi ◽  
Slobodan Jaric
Keyword(s):  
Concurrent Validity ◽  
Reaction Force ◽  
Correlation Coefficients ◽  
Leg Muscles ◽  
Relative Contribution ◽  
Load Increase ◽  
Force Velocity ◽  
Multijoint Movements ◽  
Relationship Of ◽  
Work Done

The aims of the current study were to explore the pattern of the force–velocity (F–V) relationship of leg muscles, evaluate the reliability and concurrent validity of the obtained parameters, and explore the load associated changes in the muscle work and power output. Subjects performed maximum vertical countermovement jumps with a vest ranging 0–40% of their body mass. The ground reaction force and leg joint kinematics and kinetics were recorded. The data revealed a strong and approximately linear F–V relationship (individual correlation coefficients ranged from 0.78–0.93). The relationship slopes, F- and V-intercepts, and the calculated power were moderately to highly reliable (0.67 < ICC < 0.91), while the concurrent validity F- and V-intercepts, and power with respect to the directly measured values, was (on average) moderate. Despite that a load increase was associated with a decrease in both the countermovement depth and absolute power, the absolute work done increased, as well as the relative contribution of the knee work. The obtained findings generally suggest that the loaded vertical jumps could not only be developed into a routine method for testing the capacities of leg muscles, but also reveal the mechanisms of adaptation of multijoint movements to different loading conditions.

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)

Temperature and force-velocity relationship of human muscles

1977 ◽  
Vol 42 (4) ◽  
pp. 471-475 ◽  
Author(s):  
R. A. Binkhorst ◽  
L. Hoofd ◽  
A. C. Vissers
Keyword(s):  
Temperature Effect ◽  
Coefficient Of Variation ◽  
Repeated Measurements ◽  
Muscle Temperature ◽  
Maximal Velocity ◽  
Maximal Power ◽  
Velocity Relationship ◽  
Force Velocity ◽  
Human Muscles ◽  
Relationship Of

The force-velocity relationship of maximal contractions with the handgrip muscles is established in a group of subjects. The effect of different muscle temperatures is studied. The parameters vo (maximal velocity), Fo (maximal force), Pmax (maximal power), a/Fo and H (both parameters describing the shape of the curve), and Ft/Fo (the value of the force at which power is maximal) are established. It is shown that 1) in repeated measurements the coefficient of variation in general is less than 10% for all the parameters except a/Fo; 2) the parameter a/Fo should be discarded in comparative measurements since it is not linearly related to the course of the curve. A parameter called H should be used instead to describe the curvature; 3) an increase in muscle temperature is accompanied by an increase in magnitude of all parameters except Fo. The temperature effect expressed as Q10 in the range 22–38 degrees C is in the order of 1.2.

scholarly journals The biphasic force-velocity relationship in whole rat skeletal muscle in situ

2007 ◽  
Vol 102 (6) ◽  
pp. 2294-2300 ◽  
Author(s):  
A. N. Devrome ◽  
B. R. MacIntosh
Keyword(s):  
Isometric Force ◽  
Medial Gastrocnemius ◽  
Maximal Velocity ◽  
Velocity Data ◽  
Shortening Velocity ◽  
Data Set ◽  
Velocity Relationship ◽  
Force Velocity ◽  
The Hill

Edman has reported that the force-velocity relationship (FVR) departs from Hill's classic hyperbola near 0.80 of measured isometric force ( J Physiol 404: 301–321, 1988). The purpose of this study was to investigate the biphasic nature of the FVR in the rested state and after some recovery from fatigue in the rat medial gastrocnemius muscle in situ. Force-velocity characteristics were determined before and during recovery from fatigue induced by intermittent stimulation at 170 Hz for 100 ms each second for 6 min. Force-velocity data were obtained for isotonic contractions with 100 ms of 200-Hz stimulation, including several measurements with loads above 0.80 of measured isometric force. The force-velocity data obtained in this study were fit well by a double-hyperbolic equation. A departure from Hill's classic hyperbola was found at 0.88 ± 0.01 of measured isometric force, which is higher than the ∼0.80 reported by Edman et al. for isolated frog fibers. After 45 min of recovery, maximum shortening velocity was 86 ± 2% of prefatigue, but neither curvature nor predicted isometric force was significantly different from prefatigue. The location of the departure from Hill's classic hyperbola was not different after this recovery from the fatiguing contractions. Including an isometric point in the data set will not yield the same values for maximal velocity and the degree of curvature as would be obtained using the double hyperbola approach. Data up to 0.88 of measured isometric force can be used to fit data to the Hill equation.

scholarly journals The addition of very light loads into the routine testing of the bench press increases the reliability of the force–velocity relationship

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e5835 ◽  
Author(s):  
Jesualdo Cuevas-Aburto ◽  
David Ulloa-Díaz ◽  
Paola Barboza-González ◽  
Luis Javier Chirosa-Ríos ◽  
Amador García-Ramos
Keyword(s):  
Concurrent Validity ◽  
Bench Press ◽  
Maximum Velocity ◽  
Upper Body ◽  
Routine Testing ◽  
Smith Method ◽  
Free Weight ◽  
Force Velocity ◽  
Relationship Of ◽  
Very High

Background The aim of this study was to examine whether the addition of very light loads for modeling the force–velocity (F–V) relationship during the bench press (BP) exercise can confirm its experimental linearity as well as to increase the reliability and concurrent validity of the F–V relationship parameters (maximum force (F0), maximum velocity (V0), F–V slope, and maximum power (Pmax)). Method The F–V relationship of 19 healthy men were determined using three different methods: (I) 6-loads free method: six loads performed during the traditional free-weight BP exercise (≈ 1–8–29–39–49–59 kg), (II) 4-loads free method: four loads performed during the traditional free-weight BP exercise (≈ 29–39–49–59 kg), and (III) 4-loads Smith method: four loads performed during the ballistic bench press throw exercise in a Smith machine (≈ 29–39–49–59 kg). Results The linearity of the F–V relationship was very high and comparable for the three F–V methods (p = 0.204; median Pearson’s correlation coefficient (r) = 0.99). The three methods were ranked from the most to the least reliable as follows: 6-loads free (coefficient of variation (CV) range = 3.6–6.7%) > 4-loads Smith (CV range = 4.6–12.4%) > 4-loads free (CV range = 3.8–14.5%). The higher reliability of the 6-loads free method was especially pronounced for F–V slope (CVratio ≥ 1.85) and V0 (CVratio ≥ 1.49) parameters, while the lowest difference in reliability was observed for F0 (CVratio ≤ 1.27). The 6-loads free and 4-loads free methods showed a very high concurrent validity respect to the 4-loads Smith method for F0 and Pmax (r ≥ 0.89), a moderate validity for the F–V slope (r = 0.66–0.82), and a low validity for V0 (r ≤ 0.37). Discussion The routine testing of the F–V relationship of upper-body muscles through the BP exercise should include trials with very light loading conditions to enhance the reliability of the F–V relationship.

scholarly journals Erratum to: Force–velocity relationship of leg extensors obtained from loaded and unloaded vertical jumps

2014 ◽  
Vol 115 (1) ◽  
pp. 223-224
Author(s):  
Ivan Cuk ◽  
Milos Markovic ◽  
Aleksandar Nedeljkovic ◽  
Dusan Ugarkovic ◽  
Milos Kukolj ◽  
...  
Keyword(s):  
Velocity Relationship ◽  
Force Velocity ◽  
Leg Extensors ◽  
Relationship Of ◽  
Vertical Jumps

scholarly journals NORMATIVE ISOMETRIC HIP MUSCLE FORCE VALUES ASSESSED BY A MANUAL DYNAMOMETER

2019 ◽  
Vol 27 (2) ◽  
pp. 124-128 ◽  
Author(s):  
Glauber Alvarenga ◽  
Henry Dan Kiyomoto ◽  
Emília Cardoso Martinez ◽  
Giancarlo Polesello ◽  
Vera Lúcia dos Santos Alves
Keyword(s):  
Body Weight ◽  
Muscle Force ◽  
Isometric Force ◽  
Return To Sports ◽  
Level Of Evidence ◽  
Hip Muscle ◽  
Extensor Muscles ◽  
Muscle Groups ◽  
The Impact ◽  
External Rotator

ABSTRACT Objective: Hand-held dynamometry is a quantitative and accessible means of determining the isometric force of muscle groups. Methods: A total of 52 women aged 20–29 years with no complaints of hip pain who were sedentary or sporadically active and had a body mass index of 18.5–24.99 kg/m2 were included. All participants underwent bilateral assessments using hand-held dynamometry of the flexor, extensor, adductor, and abductor muscles as well as the internal and external rotator hip muscles. All hip movements were measured. All contraction data collected by the dynamometer are expressed in kilograms, normalized according to body weight, and expressed as percentages. Results: The flexor muscles exhibited an isometric muscle force of 38.54% of body weight versus a muscle force of 27.04% for the extensor muscles, 16.89% for the adductors, 16.85% for the abductors, and 17.09% for the external rotators, and 23.82% for the internal rotators. Conclusion: Standardization of isometric strength values according to body weight proved feasible. This result is important for clinical practice since it allows the establishment of patterns of normality and criteria for discharge, return to sports, or assessment of the impact of injuries in terms of loss of muscle strength. Level of evidence: III, Development of diagnostic criteria on consecutive patients (with universally applied reference “gold” standard).

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