A Novel Two-Velocity Method for Elaborate Isokinetic Testing of Knee Extensors

Grbić, Vladimir; Djuric, Sasa; Knežević, Olivera M.; Mirkov, Dragan M.; Nedeljković, Aleksandar; Jarić, Slobodan

doi:10.1055/s-0043-113043

Cited by 29 publications

(31 citation statements)

References 29 publications

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“…Larger differences between SPEED and TECH may also be apparent when testing older World Cup skiers due to a longer exposition to specific training than younger skiers competing at lower levels. The force-velocity relationship is strongly linear for the quadriceps and the 60º.s − 1 and 180º.s − 1 reported in the current study have been shown to be sufficient to characterize this relationship [29]. Thus, the current results can be extrapolated to other isokinetic protocols.…”

Section: Discussionsupporting

confidence: 55%

Discipline and Sex Differences in Angle-specific Isokinetic Analysis in Elite Skiers

et al. 2019

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Standard outcomes of traditional isokinetic testing do not detect differences between various muscle mechanical properties. This study i) explored a novel analysis throughout the range of motion based on statistical parametric mapping and ii) examined the impact of sex and discipline on hamstrings/quadriceps torque in elite alpine skiers. Twenty-eight national team skiers (14 females, 14 males; 14 technical, 14 speed) undertook an isokinetic evaluation of the knee flexors/extensors (range 30–90°, 0° representing full extension). There was no effect of sex (p=0.864, d=0.03) and discipline (p=0.360, d=0.17) on maximal hamstrings-to-quadriceps ratio and no effect of discipline on maximal torque (p>0.156, d≤0.25). Hamstrings torque and hamstrings-to-quadriceps ratio were lower in females than males toward knee extension only (p<0.05). Quadriceps torque was greater after 72° of knee flexion in technicians than downhill skiers (p<0.05). The current data showed that statistical parametric mapping analysis identified angle-specific differences that could not be evidenced when analyzing only maximal torques and reconstructed ratios. This may enhance screening methods to identify pathologic knee function or monitor rehabilitation programs, and inform sex- and discipline-specific training in alpine skiing.

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Section: Discussionsupporting

confidence: 55%

Discipline and Sex Differences in Angle-specific Isokinetic Analysis in Elite Skiers

et al. 2019

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“…The two-point method was proposed by Jaric (2016) to simplify the testing procedure of the F-V relationship. Previous studies have confirmed that the two-point method can provide reliable and valid F-V relationship parameters in different exercises (Garcia-Ramos, Zivkovic, et al, 2018;Garcia-Ramos & Jaric, 2018a;Grbic et al, 2017), including vertical jumps (Garcia-Ramos, Pérez-Castilla, et al, 2018;Zivkovic et al, 2017). However, this is the first study that has applied the two-point method under field conditions (i.e., only two loads applied) to determine the F-V relationship during vertical jumps.…”

Section: Discussionmentioning

confidence: 82%

Assessment of the force‐velocity relationship during vertical jumps: influence of the starting position, analysis procedures and number of loads

Janićijević

Knežević

Mirkov

et al. 2019

European Journal of Sport Science

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This study aimed to compare the reliability and magnitude of the force-velocity (F-V) relationship parameters between the squat jumps performed from the 90º (SJ90) and selfpreferred knee angle (SJpref). A secondary aim was to explore the effect of the analysis procedure (force platform [FP] and Samozino's [SAM] method) and the number of loads tested (three-and two-point methods) on the F-V relationships. Twelve men were tested in two sessions during the SJ90 and SJpref. Two identical blocks of jumps were performed in each session against three external loads. The F-V relationship parameters (maximum force, maximum velocity, F-V slope and maximum power) were determined at each block through the FP and SAM procedures using the data collected under three (three-point method) or only the two most distant loads (two-point method). The average coefficient of variation (CV) of the four F-V parameters revealed a higher reliability for the SJ90 compared to the SJpref (5.86% vs. 7.55%; CVratio=1.29) with more pronounced differences using the FP (CVratio=1.43) than the SAM procedure (CVratio=1.14), and higher reliability for the SAM compared to the FP (6.14% vs. 7.27%; CVratio=1.18). The SJpref and SAM procedures provided comparable or higher magnitude of the F-V relationship parameters than the SJ90 and FP, respectively. The three-and two-point methods revealed a comparable reliability and trivial differences in the magnitude of the F-V relationship parameters. The routine testing procedure of the F-V relationship could be simplified using the SJpref, the SAM procedure and the two-point method.

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“…The linear F-V relationships for both jumps in our study were strong (r = − 0.95). Some authors have suggested that F-V relationship during single-joint isokinetic tasks might be slightly curvilinear 39 . If this is also the case with multi-joint movements, the overestimation of the maximal isometric force in our study could be partially attributed to non-linearity of the F-V relationship near the zero velocity.…”

Section: Discussionmentioning

confidence: 99%

Force–velocity profile during vertical jump cannot be assessed using only bodyweight jump and isometric maximal voluntary contraction tasks

Šarabon

Kozinc

Marković

2020

Sci Rep

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Recently, the two-point method of force–velocity (F–V) profiling of multi-joint human movements has been introduced and validated. In this study, we investigated the validity of estimating the jumping F–V profile using only bodyweight jump and isometric maximal voluntary contraction (MVC) task. Participants (n = 30) performed 3 repetitions of squat (SJ) and counter-movement jumps (CMJ), each at loads that were progressively increased by 10 kg increments, with the number of loads depending on the individual’s ability. Then, 3 isometric MVC trials were performed in 3 knee angles (30°, 60° and 90°). F–V profiling of SJ and CMJ were performed using the multiple-point method, the two-point method, and the novel Jump-MVC method. The results showed poor to fair validity of the novel Jump-MVC method for assessing jumping F–V profile (most ICC < 0.5, most CV > 10%, significant systematic bias present, and the presence of proportional bias). The exception was the estimation of theoretical maximal power, which was highly valid for both SJ and CMJ (ICC = 0.91–0.95; CV = 5.0–6.3%). In contrast, validity of the two-point method was excellent (all ICC > 0.90; CV = 2–6%). Although additional studies are needed, present results suggest that the F–V profiling of vertical jumps should be performed using the two-point method with distal loads.

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A Novel Two-Velocity Method for Elaborate Isokinetic Testing of Knee Extensors

Cited by 29 publications

References 29 publications

Discipline and Sex Differences in Angle-specific Isokinetic Analysis in Elite Skiers

Discipline and Sex Differences in Angle-specific Isokinetic Analysis in Elite Skiers

Assessment of the force‐velocity relationship during vertical jumps: influence of the starting position, analysis procedures and number of loads

Force–velocity profile during vertical jump cannot be assessed using only bodyweight jump and isometric maximal voluntary contraction tasks

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