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Simon Avrillon, Boris Jidovtseff, François Hug and Gaël Guilhem

Purpose:

Muscle strengthening is commonly based on the use of isoinertial loading, whereas variable resistances such as pneumatic loading may be implemented to optimize training stimulus. The purpose of the current study was to determine the effect of the ratio between pneumatic and isoinertial resistance on the force–velocity relationship during ballistic movements.

Methods:

A total of 15 participants performed 2 concentric repetitions of ballistic bench-press movements with intention to throw the bar at 30%, 45%, 60%, 75%, and 90% of the maximal concentric repetition with 5 resistance ratios including 100%, 75%, 50%, 25%, or 0% of pneumatic resistance, the additional load being isoinertial. Force-, velocity-, and power-time patterns were assessed and averaged over the concentric phase to determine the force–velocity and power–velocity relationships for each resistance ratio.

Results:

Each 25% increase in the pneumatic part in the resistance ratio elicited higher movement velocity (+0.11 ± 0.03 m/s from 0% to 80% of the concentric phase) associated with lower force levels (–43.6 ± 15.2 N). Increased isoinertial part in the resistance ratio resulted in higher velocity toward the end of the movement (+0.23 ± 0.01 m/s from 90% to 100%).

Conclusions:

The findings show that the resistance ratio could be modulated to develop the acceleration phase and force toward the end of the concentric phase (pneumatic-oriented resistance). Inversely, isoinertial-oriented resistance should be used to develop maximal force and maximal power. Resistance modality could, therefore, be considered an innovative variable to modulate the training stimulus according to athletic purposes.

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Amador García-Ramos, Slobodan Jaric, Paulino Padial and Belén Feriche

This study aimed to (1) evaluate the linearity of the force–velocity relationship, as well as the reliability of maximum force (F 0), maximum velocity (V 0), slope (a), and maximum power (P 0); (2) compare these parameters between the traditional and ballistic bench press (BP); and (3) determine the correlation of F 0 with the directly measured BP 1-repetition maximum (1RM). Thirty-two men randomly performed 2 sessions of traditional BP and 2 sessions of ballistic BP during 2 consecutive weeks. Both the maximum and mean values of force and velocity were recorded when loaded by 20–70% of 1RM. All force–velocity relationships were strongly linear (r > .99). While F 0 and P 0 were highly reliable (ICC: 0.91–0.96, CV: 3.8–5.1%), lower reliability was observed for V 0 and a (ICC: 0.49–0.81, CV: 6.6–11.8%). Trivial differences between exercises were found for F 0 (ES: < 0.2), however the a was higher for the traditional BP (ES: 0.68–0.94), and V 0 (ES: 1.04–1.48) and P 0 (ES: 0.65–0.72) for the ballistic BP. The F 0 strongly correlated with BP 1RM (r: 0.915–0.938). The force–velocity relationship is useful to assess the upper body maximal capabilities to generate force, velocity, and power.

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Amador García-Ramos and Slobodan Jaric

 = ( F 0 · V 0 )/4). Figure 1 —Force–velocity relationships obtained by a representative subject through the 6-load multiple-point method (straight line; the 6 loads were used), 4-load multiple-point method (line with long dashes; the 4 intermediate loads were used), and 2-point method (dotted line; only

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Tom G. Welter, Maarten F. Bobbert, Bauke M. van Bolhuis, Stan C.A.M. Gielen, Leonard A. Rozendaal and Dirkjan H.E.J. Veeger

We have investigated whether differences in EMG activity in mono- and bi-articuiar muscles for concentric and eccentric contractions (van Bolhuis, Gielen, & van Ingen Schenau, 1998) have to be attributed to a specific muscle coordination strategy or whether they are merely a demonstration of adaptations necessary to adjust for muscle contractile properties. Slow, multi-joint arm movements were studied in a horizontal plane with an external force applied at the wrist. Kinematics and electromyography data from 10 subjects were combined with data from a 3-D model of the arm and a Hill-type muscle model Data for both mono- and bi-articular muscles revealed a higher activation in concentric than in eccentric contractions. The model calculations indicated that the measured difference in activation (20%) was much larger than expected based on the force-velocity relationship (predicting changes of ~5%). Although these findings eliminate the force-velocity relationship as the main explanation for changes in EMG, it cannot be ruled out that other muscle contractile properties, such as history dependence of muscle force, determine muscle activation levels in the task that was studied.

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Daniel Feeney, Steven J. Stanhope, Thomas W. Kaminski, Anthony Machi and Slobodan Jaric

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.

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Irineu Loturco, Lucas A. Pereira, Ciro Winckler, Weverton L. Santos, Ronaldo Kobal and Michael McGuigan

worthwhile to examine if the force–velocity relationship remains stable or even undisturbed in this selected group of athletes. Therefore, the purpose of this study was to analyze the relationship between force and velocity and determine the 1RM bar velocity in the BP exercise in national Paralympic

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Abderrahmane Rahmani, Pierre Samozino, Jean-Benoit Morin and Baptiste Morel

.0b013e3182a1da46 23838968 10.1519/JSC.0b013e3182a1da46 3. García-Ramos A , Jaric S , Padial P , Feriche B . Force–velocity relationship of upper body muscles: traditional versus ballistic bench press . J Appl Biomech . 2016 ; 32 ( 2 ): 178 – 185 . doi:10.1123/jab.2015-0162 26540734 10

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Amador García-Ramos, Alejandro Torrejón, Antonio J. Morales-Artacho, Alejandro Pérez-Castilla and Slobodan Jaric

force-velocity relationship of leg muscles based on varying applied resistive forces has been proposed. 7 Similarly, recent studies have indicated that some functional tests (eg, jumping, sprinting, lifting) performed either against different loads or at different velocities reveal approximately linear

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Andrea Monte, Francesca Nardello and Paola Zamparo

Purpose:

The effects of different loads on kinematic and kinetic variables during sled towing were investigated with the aim to identify the optimal overload for this specific sprint training.

Methods:

Thirteen male sprinters (100-m personal best: 10.91 ± 0.14 s) performed 5 maximal trials over a 20-m distance in the following conditions: unloaded and with loads from 15% to 40% of the athlete’s body mass (BM). In these calculations the sled mass and friction were taken into account. Contact and flight times, stride length, horizontal hip velocity (vh), and relative angles of hip, knee, and ankle (at touchdown and takeoff) were measured step by step. In addition, the horizontal force (Fh) and power (Ph) and maximal force (Fh0) and power (Ph0) were calculated.

Results:

vh, flight time, and step length decreased while contact time increased with increasing load (P < .001). These variables changed significantly also as a function of the step number (P < .01), except between the 2 last steps. No differences were observed in Fh among loads, but Fh was larger in sled towing than in unloaded. Ph was unaffected by load up to +20%BM but decreased with larger loads. Fh0 and Ph0 were achieved at 20%BM. Up to 20%BM, no significant effects on joint angles were observed at touchdown and takeoff, while at loads >30%BM joint angles tended to decrease.

Conclusion:

The 20%BM condition represents the optimal overload for peak power production—at this load sprinters reach their highest power without significant changes in their running technique (eg, joint angles).

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Pedro Jiménez-Reyes, Pierre Samozino, Fernando Pareja-Blanco, Filipe Conceição, Víctor Cuadrado-Peñafiel, Juan José González-Badillo and Jean-Benoît Morin

Purpose:

To analyze the reliability and validity of a simple computation method to evaluate force (F), velocity (v), and power (P) output during a countermovement jump (CMJ) suitable for use in field conditions and to verify the validity of this computation method to compute the CMJ force–velocity (Fv) profile (including unloaded and loaded jumps) in trained athletes.

Methods:

Sixteen high-level male sprinters and jumpers performed maximal CMJs under 6 different load conditions (0–87 kg). A force plate sampling at 1000 Hz was used to record vertical ground-reaction force and derive vertical-displacement data during CMJ trials. For each condition, mean F, v, and P of the push-off phase were determined from both force-plate data (reference method) and simple computation measures based on body mass, jump height (from flight time), and push-off distance and used to establish the linear Fv relationship for each individual.

Results:

Mean absolute bias values were 0.9% (± 1.6%), 4.7% (± 6.2%), 3.7% (± 4.8%), and 5% (± 6.8%) for F, v, P, and slope of the Fv relationship (SFv), respectively. Both methods showed high correlations for Fv-profile-related variables (r = .985–.991). Finally, all variables computed from the simple method showed high reliability, with ICC >.980 and CV <1.0%.

Conclusions:

These results suggest that the simple method presented here is valid and reliable for computing CMJ force, velocity, power, and Fv profiles in athletes and could be used in practice under field conditions when body mass, push-off distance, and jump height are known.