Reliability of Isometric Force-time Curve Parameters for Men Aged 20 to 79 Years

Purpose: (1) To analyze the associations between serve velocity (SV) and various single-joint upper-limb isometric force–time curve parameters, (2) to develop a prediction model based on the relationship between these variables, and (3) to determine whether these factors are capable of discriminating between tennis players with different SV performances. Method: A total of 17 high-performance tennis players performed 8 isometric tests of joints and movements included in the serve kinetic chain (wrist and elbow flexion [EF] and extension; shoulder flexion [SHF] and extension [SHE], internal [SHIR] and external rotation). Isometric force (IF), rate of force development (RFD), and impulse (IMP) at different time intervals (0–250 ms) were obtained for analysis. Results: Significant (P < .05 to P < .01) and moderate to very large correlations were found between SV and isometric force (IF), RFD and impulse (IMP) at different time intervals in all joint positions tested (except for the EF). Stepwise multiple regression analysis highlighted the importance of RFD in the SHIR from 0 to 50 milliseconds and isometric force (IF) in the SHF at 250 milliseconds on SV performance. Moreover, the discriminant analyses established SHIR RFD from 0 to 30 milliseconds as the most important factor discriminating players with different serve performances. Conclusions: Force–time parameters in upper-limb joints involved in the serve moderate to very largely influence SV. Findings suggest that the capability to develop force in short periods of time (<250 ms), especially in the shoulder joint, seems relevant to develop high SV in competition tennis players.

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The Effect of Static Stretching on Maximal Voluntary Contraction and Force-Time Curve Characteristics

Journal of Sport Rehabilitation ◽

10.1123/jsr.15.3.185 ◽

2006 ◽

Vol 15 (3) ◽

pp. 185-194 ◽

Cited By ~ 7

Author(s):

Christos Papadopoulos ◽

Vasilios I. Kalapotharakos ◽

Georgios Noussios ◽

Konstantinos Meliggas ◽

Evangelia Gantiraga

Keyword(s):

Maximal Voluntary Contraction ◽

Isometric Force ◽

Rectus Femoris ◽

Biceps Femoris ◽

Voluntary Contraction ◽

Emg Activity ◽

Static Stretching ◽

Time Curve ◽

Significant Difference ◽

Force Time

Objective:To examine the effect of static stretching on maximal voluntary contraction (MVC) and isometric force-time curve characteristics of leg extensor muscles and EMG activity of rectus femoris (RF), biceps femoris (BF), and gastrocnemius (GA).Design:A within subjects experimental design.Participants:Ten healthy students were tested after a jogging and a jogging/stretch protocol.Intervention:The stretching protocol involved a 10 min jog and seven static stretching exercises.Main Outcomes:Measurements included MVC, time achieved to MVC (TMVC), force at 100ms (F100), index of relative force (IRF), index of rate of force development (IRFD), and average integrated EMG activity (AEMG).Results:There were slight but no significant changes in MVC (1%), TMVC(4.8%), F100(7.8%), IRF (1%), and IRFD(3.5%) between measurement. A significant difference (21%;P< 0.05) in AEMG of RF was found.Conclusions:The present study indicated that a moderate volume of static stretching did not alter significantly the MVC and the isometric force-time curve characteristics. Neural inhibition, as it is reflected from AEMG of RF, did not alter MVC and isometric force-time curve characteristics.

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INDICATORS OF NEUROMUSCULAR FATIGUE IN LEG PRESS EXERCISE IN MEN AND WOMEN

Revista Brasileira de Medicina do Esporte ◽

10.1590/1517-869220202603216124 ◽

2020 ◽

Vol 26 (3) ◽

pp. 243-247

Author(s):

Camila Brasileiro Azevedo Barros ◽

Manoel da Cunha Costa ◽

Antônio Gonçalves dos Santos Neto ◽

José Hildemar Teles Gadelha ◽

Brendha Stephany Rodrigues da Silva ◽

...

Keyword(s):

Muscle Activation ◽

Isometric Force ◽

Maximum Voluntary Contraction ◽

Voluntary Contraction ◽

Level Of Evidence ◽

Similar Reduction ◽

Time Curve ◽

Men And Women ◽

Leg Press ◽

Force Time

ABSTRACT Introduction Muscle fatigue is characterized by reduced ability to produce maximum strength or power, and may differ between men and women. Changes in velocity of movement during exercise, and in the ability to produce strength after exercise, may help when comparing fatigue in men and women. Objective To analyze the differences between men and women in relation to number of repetitions, kinetics, kinematics and isometric force-time curve performance, and their respective muscle activation in horizontal leg press exercises. Methods Fifteen men and fifteen women underwent isometric force-time curve (Cf-t) and electromyographic (EMG) assessments before and after performing horizontal leg press exercises. The exercises were performed in three sets until voluntary exhaustion, at 70% maximal repetition. During the exercises, kinetic and kinematic variables were obtained by means of two force transducers, a linear position potentiometer and accelerometer adapted for the horizontal leg press and synchronized by a signal conditioning plate. Results The mean propulsive velocity significantly reduced between the first and last repetition of each series, with a similar reduction for men (-12.4 to -29.2%) and women (-29.2 to -35.6%). The same pattern was observed for the other kinetic and kinematic variables. The maximum voluntary contraction and peak force development rate also decreased for both men (-15.1 ± 8.7% and -26.9 ± 21.2%, respectively) and women (-13.9 ± 10.4% and -28.2 ± 11.5%, respectively). Conclusion Based on the different variables used to quantify the effect of fatigue during and after horizontal leg press exercises, the research found practically no differences between men and women. Level of evidence II; Comparative prospective study.

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Reliability of Isometric Force-time Curve Parameters for Men Aged 20 to 79 Years

The Journal of Strength and Conditioning Research ◽

10.1519/00124278-199208000-00006 ◽

1992 ◽

Vol 6 (3) ◽

pp. 158-164

Author(s):

Michael G. Bemben ◽

Benjamin H. Massey ◽

Richard A. Boileau ◽

James E. Misner

Keyword(s):

Isometric Force ◽

Time Curve ◽

Force Time

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Relationship Between Strength Characteristics and Unweighted and Weighted Vertical Jump Height

International Journal of Sports Physiology and Performance ◽

10.1123/ijspp.4.4.461 ◽

2009 ◽

Vol 4 (4) ◽

pp. 461-473 ◽

Cited By ~ 96

Author(s):

Jenna M. Kraska ◽

Michael W. Ramsey ◽

G. Gregory Haff ◽

Nate Fethke ◽

William A. Sands ◽

...

Keyword(s):

Body Mass ◽

Isometric Force ◽

Vertical Jump ◽

Force Plate ◽

Collegiate Athletes ◽

Practical Method ◽

Relative Strength ◽

Jump Height ◽

Time Curve ◽

Force Time

Purpose:To investigate the relationship between maximum strength and differences in jump height during weighted and unweighted (body weight) static (SJ) and countermovement jumps (CMJ).Methods:Sixty-three collegiate athletes (mean ± SD; age= 19.9 ± 1.3 y; body mass = 72.9 ± 19.6 kg; height = 172.8 ± 7.7 cm) performed two trials of the SJ and CMJ with 0 kg and 20 kg on a force plate; and two trials of mid-thigh isometric clean pulls in a custom rack over a force plate (1000-Hz sampling). Jump height (JH) was calculated from fight time. Force-time curve analyses determined the following: isometric peak force (IPF), isometric force (IF) at 50, 90, and 250 ms, and isometric rates of force development (IRFD). Absolute and allometric scaled forces, [absolute force/(body mass0.67)], were used in correlations.Results:IPF, IRFD, F50a, F50, F90, and F250 showed moderate/strong correlations with SJ and CMJ height percent decrease from 0 to 20 kg. IPFa and F250a showed weak/moderate correlations with percent height decrease. Comparing strongest (n = 6) to weakest (n = 6): t tests revealed that stronger athletes (IPFa) performed superior to weaker athletes.Conclusion:Data indicate the ability to produce higher peak and instantaneous forces and IRFD is related to JH and to smaller differences between weighted and unweighted jump heights. Stronger athletes jump higher and show smaller decrements in JH with load. A weighted jump may be a practical method of assessing relative strength levels.

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