Reliability of Maximum Isometric Force-Time Parameters during a Leg Press Test in Pubertal Basketball Players

2002 ◽  
Vol 14 (2) ◽  
pp. 193-201 ◽  
Author(s):  
Panagiotis Ioakimidis ◽  
Vasilios Gerodimos ◽  
Eleftherios Kellis ◽  
Spiros Kellis
Keyword(s):  
Isometric Force ◽  
Intraclass Correlation ◽  
Correlation Coefficients ◽  
Basketball Players ◽  
Leg Press ◽  
Maximal Force ◽  
Maximum Isometric Force ◽  
Time Parameters ◽  
Relative Scale ◽  
Force Time

Fifteen young basketball players (aged 14.4 – 0.5 yrs) underwent two identical testing sessions spaced one week apart, to determine the reliability of maximum isometric force and force-time parameters during a maximal bilateral isometric leg press effort. The maximal isometric force (MIF), the ratio of maximal force to time (TMIF) to attain maximal force (ARMIF), starting strength (F50), and on a relative scale the time taken to increase the force from 10% to 30%, 60%, and 90% of maximal force were calculated. High intraclass correlation coefficients (ICC) were found for MIF (0.96), ARMIF (0.85), and F50 (0.90). On the relative scale, the ICCs for the times to produce 30%, 60%, and 90% of maximum force were 0.94, 0.95, 0.95, respectively. The present results indicate that maximum isometric force and the force-time parameters during a bilateral leg press can be measured reliably in pubertal basketball players.

scholarly journals Assessing Muscle-Strength Asymmetry via a Unilateral-Stance Isometric Midthigh Pull

2017 ◽  
Vol 12 (4) ◽  
pp. 505-511 ◽  
Author(s):  
Thomas Dos’Santos ◽  
Christopher Thomas ◽  
Paul A. Jones ◽  
Paul Comfort
Keyword(s):  
College Athletes ◽  
Isometric Force ◽  
Intraclass Correlation ◽  
Force Plate ◽  
Correlation Coefficients ◽  
Rugby League ◽  
Intraclass Correlation Coefficients ◽  
Male College ◽  
Strength Asymmetry ◽  
Force Time

Purpose:To investigate the within-session reliability of bilateral- and unilateral-stance isometric midthigh-pull (IMTP) force–time characteristics including peak force (PF), relative PF, and impulse at time bands (0–100, 0–200, 0–250, and 0–300 milliseconds) and to compare isometric force–time characteristics between right and left and dominant (D) and nondominant (ND) limbs.Methods:Professional male rugby league and multisport male college athletes (N = 54; age, 23.4 ± 4.2 y; height, 1.80 ± 0.05 m; mass, 88.9 ± 12.9 kg) performed 3 bilateral IMTP trials and 6 unilateral-stance IMTP trials (3 per leg) on a force plate sampling at 600 Hz.Results:Intraclass correlation coefficients (ICCs) and coefficients of variation (CVs) demonstrated high within-session reliability for bilateral and unilateral IMTP PF (ICC = .94, CV = 4.7–5.5%). Lower reliability measures and greater variability were observed for bilateral and unilateral IMTP impulse at time bands (ICC = .81–.88, CV = 7.7–11.8%). Paired-sample t tests and Cohen d effect sizes revealed no significant differences for all isometric force–time characteristics between right and left limbs in male college athletes (P >.05, d ≤ 0.32) and professional rugby league players (P > .05, d ≤ 0.11); however, significant differences were found between D and ND limbs in male college athletes (P < .001, d = 0.43–0.91) and professional rugby league players (P < .001, d = 0.27–0.46).Conclusion:This study demonstrated high within-session reliability for unilateral-stance IMTP PF, revealing significant differences in isometric force–time characteristics between D and ND limbs in male athletes.

scholarly journals Intramuscular fiber conduction velocity, isometric force and explosive performance

2016 ◽  
Vol 51 (1) ◽  
pp. 93-101 ◽  
Author(s):  
Spyridon Methenitis ◽  
Gerasimos Terzis ◽  
Nikolaos Zaras ◽  
Angeliki-Nikoletta Stasinaki ◽  
Nikolaos Karandreas
Keyword(s):  
Conduction Velocity ◽  
Muscle Fiber ◽  
Isometric Force ◽  
Vastus Lateralis ◽  
Rate Of Force Development ◽  
Muscle Fiber Conduction Velocity ◽  
Force Development ◽  
Leg Press ◽  
Explosive Performance ◽  
Maximum Isometric Force

Abstract Conduction of electrical signals along the surface of muscle fibers is acknowledged as an essential neuromuscular component which is linked with muscle force production. However, it remains unclear whether muscle fiber conduction velocity (MFCV) is also linked with explosive performance. The aim of the present study was to investigate the relationship between vastus lateralis MFCV and countermovement jumping performance, the rate of force development and maximum isometric force. Fifteen moderately-trained young females performed countermovement jumps as well as an isometric leg press test in order to determine the rate of force development and maximum isometric force. Vastus lateralis MFCV was measured with intramuscular microelectrodes at rest on a different occasion. Maximum MFCV was significantly correlated with maximum isometric force (r = 0.66, p < 0.01), nevertheless even closer with the leg press rate of force development at 100 ms, 150 ms, 200 ms, and 250 ms (r = 0.85, r = 0.89, r = 0.91, r = 0.92, respectively, p < 0.01). Similarly, mean MFCV and type II MFCV were better correlated with the rate of force development than with maximum isometric leg press force. Lower, but significant correlations were found between mean MFCV and countermovement jump power (r = 0.65, p < 0.01). These data suggest that muscle fiber conduction velocity is better linked with the rate of force development than with isometric force, perhaps because conduction velocity is higher in the larger and fastest muscle fibers which are recognized to contribute to explosive actions.

scholarly journals Identifying Reliable and Relatable Force–Time Metrics in Athletes—Considerations for the Isometric Mid-Thigh Pull and Countermovement Jump

Sports ◽  
2020 ◽  
Vol 9 (1) ◽  
pp. 4
Author(s):  
Justin J. Merrigan ◽  
Jason D. Stone ◽  
W. Guy Hornsby ◽  
Joshua A. Hagen
Keyword(s):  
Intraclass Correlation ◽  
Correlation Coefficients ◽  
Division I ◽  
Countermovement Jump ◽  
Mean Power ◽  
Time To Peak ◽  
Intraclass Correlation Coefficients ◽  
Limb Stiffness ◽  
Coefficients Of Variation ◽  
Force Time

The purpose of this study was to evaluate intrasession reliability of countermovement jump (CMJ) and isometric mid-thigh pull (IMTP) force–time characteristics, as well as relationships between CMJ and IMTP metrics. Division I sport and club athletes (n = 112) completed two maximal effort CMJ and IMTP trials, in that order, on force plates. Relative and absolute reliability were assessed using intraclass correlation coefficients (ICCs) > 0.80 and coefficients of variation (CVs) < 10%. Intrasession reliability was acceptable for the majority of the CMJ force–time metrics except for concentric rate of force development (RFD), eccentric impulse and RFD, and lower limb stiffness. The IMTP’s time to peak force, instantaneous force at 150 ms, instantaneous net force, and RFD measures were not reliable. Statistically significant weak to moderate relationships (r = 0.20–0.46) existed between allometrically scaled CMJ and IMTP metrics, with the exception of CMJ eccentric mean power not being related with IMTP performances. A majority of CMJ and IMTP metrics met acceptable reliability standards, except RFD measures which should be used with caution. Provided CMJs and IMTPs are indicative of distinct physical fitness capabilities, it is suggested to monitor athlete performance in both tests via changes in those variables that demonstrate the greatest degree of reliability.

scholarly journals The Inter-Session Reliability of Isometric Force-Time Variables and the Effects of Filtering and Starting Force

2019 ◽  
Vol 66 (1) ◽  
pp. 43-55 ◽  
Author(s):  
Gavin L. Moir ◽  
Aaron Getz ◽  
Shala E. Davis ◽  
Mário Marques ◽  
Chad A. Witmer
Keyword(s):  
Body Mass ◽  
Isometric Force ◽  
Intraclass Correlation ◽  
Time Signal ◽  
Time Intervals ◽  
Temporal Shift ◽  
Back Squat ◽  
Time Variables ◽  
Force Time

AbstractThe purposes of the present study were to assess the inter-session reliability of force-time variables recorded during isometric back squats and also to assess the effects of applying a filter to the data prior to analysis and assess the effects of different starting force thresholds on the force-time variables. Eleven resistance trained men (age: 22.5 ± 1.9 years; body mass: 90.3 ± 13.5 kg) attended two sessions where they performed isometric squats on force plates allowing the determination of force-time variables of maximal isometric force (Fmax) and different measures of the rate of force development (RFD). The force-time variables were calculated from both raw and filtered force signals. The start of the force application was determined using force thresholds of 1% or 5% of body mass (BM). Inter-session reliability for the force-time measures was assessed by calculating the intraclass correlation coefficient (ICC) and the coefficient of variation (CV) of the measures. The ICC and CV ranged from 0.03 to 0.96 and 4.6 to 168%, respectively. The application of the filter significantly reduced Fmax and peak RFD (p < 0.004) and increased the reliability of the peak RFD. The use of the 5% BM threshold increased the magnitude of many of the RFD measures (p < 0.004) and resulted in slight improvements in the reliability of these measures although the resulting temporal shift in the force-time signal would preclude accurate assessment of the early phase of the RFD (< 100 ms). The use of a 1% BM starting force threshold without a filter is recommended when using the isometric back squat protocol presented here. Furthermore, the RFD calculated within specific time intervals is recommended

scholarly journals CONCURRENT VALIDITY OF INSTRUMENTS FOR MEASURING SPEED OF MOVEMENT IN LEG PRESS EXERCISES

2020 ◽  
Vol 26 (4) ◽  
pp. 337-341
Author(s):  
Amanda Virgínia de Souza Lima Lopes ◽  
Sergio Rodrigues Moreira ◽  
Antônio Gonçalves do Santos Neto ◽  
Aline Rafaela Soares da Silva ◽  
Clécio Lima Lopes ◽  
...  
Keyword(s):  
Concurrent Validity ◽  
Intraclass Correlation ◽  
Correlation Coefficients ◽  
Reliability Test ◽  
Dynamic Force ◽  
Level Of Evidence ◽  
Mean Velocity ◽  
Movement Velocity ◽  
Leg Press ◽  
The Mean

ABSTRACT Introduction Adequate measurement of movement velocity in strength exercises can assist in the prescription and evaluation of training effects. Objective The objectives of the present study were to analyze the reliability (test-retest) and concurrent validity of the movement velocity measured by means of the electrogoniometer and accelerometer during horizontal leg press exercise at different intensities (40, 60, 80% of a maximum repetition - 1RM). Methods Eighteen young women attended the laboratory on five occasions. After determining the maximum dynamic force, two visits (separated by 48-72 hours) were used to verify the reliability (test-retest) for different speed variables in the three intensities. Results The mean propulsive velocity obtained by the goniometer showed higher Intraclass correlation coefficients (ICC) and lower coefficients of variation compared to the accelerometer. The same behavior was observed for both the mean velocity and the peak velocity. The propulsive time was more reproducible and with less variation for the accelerometer and bad CCI for both sensors were observed at 60% of 1RM. When the sensors are compared, the mean and average propulsive velocities presented moderate ratios with a large to very large standardized medium bias. Conclusion The potentiometer of the electrogoniometer can be used to estimate the velocity in the horizontal leg press exercise, especially for loads of 60 and 80%. The performance of the accelerometer was inferior to that of the potentiometer. Level of evidence II; Diagnostic studies.

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

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.

scholarly journals Can Creatine Supplementation Interfere with Muscle Strength and Fatigue in Brazilian National Level Paralympic Powerlifting?

Nutrients ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 2492
Author(s):  
Carlos Rodrigo Soares Freitas Sampaio ◽  
Felipe J. Aidar ◽  
Alexandre R. P. Ferreira ◽  
Jymmys Lopes dos Santos ◽  
Anderson Carlos Marçal ◽  
...  
Keyword(s):  
Muscle Strength ◽  
Isometric Force ◽  
National Level ◽  
Creatine Supplementation ◽  
Peak Torque ◽  
Fatigue Index ◽  
Force Peak ◽  
Maximum Isometric Force ◽  
Force Time ◽  
Blind Manner

The aim of the present study was to analyze the effect of creatine (Cr) supplementation on peak torque (PT) and fatigue rate in Paralympic weightlifting athletes. Eight Paralympic powerlifting athletes participated in the study, with 25.40 ± 3.30 years and 70.30 ± 12.15 kg. The measurements of muscle strength, fatigue index (FI), peak torque (PT), force (kgf), force (N), rate of force development (RFD), and time to maximum isometric force (time) were determined by a Musclelab load cell. The study was performed in a single-blind manner, with subjects conducting the experiments first with placebo supplementation and then, following a 7-day washout period, beginning the same protocol with creatine supplementation for 7 days. This sequence was chosen because of the lengthy washout of creatine. Regarding the comparison between conditions, Cr supplementation did not show effects on the variables of muscle force, peak torque, RFD, and time to maximum isometric force (p > 0.05). However, when comparing the results of the moments with the use of Cr and placebo, a difference was observed for the FI after seven days (U3: 1.12; 95% CI: (0.03, 2.27); p = 0.02); therefore, the FI was higher for placebo. Creatine supplementation has a positive effect on the performance of Paralympic powerlifting athletes, reducing fatigue index, and keeping the force levels as well as PT.

Reproducibility of Plantar Pressure Distribution Data in Barefoot Running

2008 ◽  
Vol 24 (1) ◽  
pp. 14-23 ◽  
Author(s):  
Christian Maiwald ◽  
Stefan Grau ◽  
Inga Krauss ◽  
Marlene Mauch ◽  
Detlef Axmann ◽  
...  
Keyword(s):  
Root Mean Square ◽  
Plantar Pressure ◽  
Intraclass Correlation ◽  
Correlation Coefficients ◽  
Distribution Data ◽  
Mean Square ◽  
Barefoot Running ◽  
Intraclass Correlation Coefficients ◽  
Force Time ◽  
Mean Square Errors

The aim of this study was to provide detailed information on rationales, calculations, and results of common methods used to quantify reproducibility in plantar pressure variables. Recreational runners (N = 95) performed multiple barefoot running trials in a laboratory setup, and pressure variables were analyzed in nine distinct subareas of the foot. Reproducibility was assessed by calculating intraclass correlation coefficients (ICC) and the root mean square error (RMSE). Intraclass correlation coefficients ranged from 0.58 to 0.99, depending on the respective variable and type of ICC. Root mean square errors ranged between 2.3 and 3.1% for relative force–time integrals, between 0.07 and 0.23 for maximum force (Fmax), and between 107 and 278 kPa for maximum pressure (Pmax), depending on the subarea of the foot. Force–time integral variables demonstrated the best within-subject reproducibility. Rear-foot data suffered from slightly increased measurement error and reduced reproducibility compared with the forefoot.

Effect of Knee and Trunk Angle on Kinetic Variables During the Isometric Midthigh Pull: Test–Retest Reliability

2015 ◽  
Vol 10 (1) ◽  
pp. 58-63 ◽  
Author(s):  
Paul Comfort ◽  
Paul. A. Jones ◽  
John J. McMahon ◽  
Robert Newton
Keyword(s):  
Knee Flexion ◽  
Isometric Force ◽  
High Reliability ◽  
Intraclass Correlation ◽  
Correlation Coefficients ◽  
Joint Angles ◽  
Force Development ◽  
Intraclass Correlation Coefficients ◽  
Hip Flexion ◽  
Test Retest Reliability

The isometric midthigh pull (IMTP) has been used to monitor changes in force, maximum rate of force development (mRFD), and impulse, with performance in this task being associated with performance in athletic tasks. Numerous postures have been adopted in the literature, which may affect the kinetic variables during the task; therefore, the aim of this investigation was to determine whether different knee-joint angles (120°, 130°, 140°, and 150°) and hip-joint angles (125° and 145°), including the subjects preferred posture, affect force, mRFD, and impulse during the IMTP. Intraclass correlation coefficients demonstrated high within-session reliability (r ≥ .870, P < .001) for all kinetic variables determined in all postures, excluding impulse measures during the 130° knee-flexion, 125° hip-flexion posture, which showed a low to moderate reliability (r = .666–.739, P < .001), while between-sessions testing demonstrated high reliability (r > .819, P < .001) for all kinetic variables. There were no significant differences in peak force (P > .05, Cohen d = 0.037, power = .408), mRFD (P > .05, Cohen d = 0.037, power = .409), or impulse at 100 ms (P > .05, Cohen d = 0.056, power = .609), 200 ms (P > .05, Cohen d = 0.057, power = .624), or 300 ms (P > .05, Cohen d = 0.061, power = .656) across postures. Smallest detectable differences demonstrated that changes in performance of >1.3% in peak isometric force, >10.3% in mRFD, >5.3% in impulse at 100 ms, >4.4% in impulse at 200 ms, and >7.1% in impulse at 300 ms should be considered meaningful, irrespective of posture.

Reliability of the Nicholas Manual Muscle Tester on Upper Body Strength in Children Ages 8-10

1992 ◽  
Vol 4 (4) ◽  
pp. 340-350 ◽  
Author(s):  
Cynthia Dawson ◽  
Ron Croce ◽  
Tim Quinn ◽  
Neil Vroman
Keyword(s):  
Isometric Force ◽  
Correlation Coefficients ◽  
Upper Body ◽  
Significant Strength ◽  
Body Strength ◽  
Upper Body Strength ◽  
Maximum Isometric Force ◽  
Males And Females ◽  
Muscle Groups ◽  
Elbow Extensor

Hand-held dynamometry has proven reliable in assessing adult strength. The primary purpose of this study was to determine its reliability in children. Secondary purposes included investigating strength differences between males and females and between dominant (D) and nondominant (ND) sides. Subjects were 8-, 9-, and 10-year-old boys (n=63) and girls (n=54). The Nicholas Manual Muscle Tester (NMMT) was used to measure maximum isometric force of D and ND elbow flexors, elbow extensors, and shoulder abductors. Retest measurements were taken 4 to 7 days later. Results indicated that (a) correlation coefficients ranging from .72 to .90 were statistically significant; (b) except for males’ ND elbow extensor strength, a series of paired t tests revealed no significant differences between test and retest strength values; (c) a series of paired t tests revealed no significant strength differences between D and ND sides other than for males’ elbow extensor strength for the test phase; and (d) a series of unpaired t tests revealed statistically significant differences between males and females on a majority of the muscle groups. The NMMT appears to be a quick and reliable testing instrument for determining maximal isometric force in children.

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