Galiano, C, Pareja-Blanco, F, Hidalgo de Mora, J, and S áez de Villarreal, E. Low-velocity loss induces similar strength gains to moderate-velocity loss during resistance training. J Strength Cond Res 36(2): 340-345, 2022-This study aimed to analyze the effects of 2 velocity-based resistance training (VBT) programs that used the same relative loading but differed in the velocity loss (VL) throughout the set: 5% (VL5) vs. 20% (VL20). Twenty-eight physically active men (age: 23.0 6 3.2 years; height: 175.8 6 4.7 cm; body mass: 73.8 6 10.8 kg) were randomly assigned to 2 groups: VL5 (n 5 15) or VL20 (n 5 13). Subjects followed a 7-week (14 sessions) VBT program using the squat exercise while repetition velocity was monitored. The following variables were assessed at pretest and posttest: estimated 1-repetition maximum (1RM); average velocity attained for all absolute loads common to pretest and posttest (AV); average velocity for those loads that were moved faster than 1 m•s 21 (AV . 1); average velocity for those loads that were moved slower than 1 m•s 21 (AV , 1); countermovement jump (CMJ); and 20-m running sprint time (T20). T20 and CMJ height were assessed before each training session to analyze their evolution during the training program. The VL5 group executed only 32.6% of the total repetitions performed by the VL20 group (156.9 6 25.0 vs. 480.5 6 162.0 rep). Both groups improved significantly (p , 0.01) in all variables analyzed (1RM, AV, AV . 1, AV , 1, CMJ, and T20) from pretest to posttest, with no significant differences between them. Therefore, a low VL (5%) induced similar gains in strength, jump, and sprint performance to a moderate VL of 20%, despite VL5 performing only 32.6% of the repetitions achieved by the VL20 group.

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Flywheel resistance training devices can be classified by their shaft shape. The objective of this study was to analyze whether using two flywheel resistance training devices shaft shapes can influence force and velocity production, regardless of the inertia used. Thirty-nine (n = 39) healthy active men participated in this study. They were randomized to perform 3 sets of 7 repetitions at maximal concentric voluntary execution, followed by a break in the last third of the eccentric phase in the half squat exercise. A progressive rotational inertial setting of 0.11, 0.22, and 0.33 kg·m2 was used. Force- and velocity-time profiles were captured using two force plates and a synchronized linear encoder. Statistical parametric mapping was used to compare biomechanical output between the flywheel devices. The level of significance was set at p < 0.05. Force application was significantly higher in the horizontal cylinder-shaped device for the three moments of inertia used in the eccentric phase (p < 0.001). In the concentric phase, force application was significantly higher in the horizontal cylinder-shaped device in 0.11 (p < 0.001) and 0.22 kg·m2 (p < 0.001). The resultant speed was higher in the vertical cone-shaped device in the concentric phase and the eccentric phase for the three moments of inertia (p < 0.001). In conclusion, the flywheel shaft type determines the mechanical output of the half squat exercise, regardless of the moment of inertia used. While a horizontal cylinder-shaped device is more suitable to achieve higher forces, especially in the eccentric phase, a vertical cone-shaped device can be used to achieve higher speeds during the execution of the exercise.

It has been showed that previous experience in the use of rotational inertia devices (RIDs) enhances acute performance outcomes. The purpose of this study was to examine the differences in kinetic and kinematic profiles between athletes with and without experience in the use of different RIDs. Thirty-nine healthy men performed a half-squat incremental test on two different RIDs: a horizontal cylinder (YY) and a vertical cone-shaped axis (CP). The participants were grouped based on experience in the use of rotational inertia devices. Time, peak velocity, peak force, time to reach peak force, average force, impulse, and range of movement were analyzed to determine the differences between groups. Several biomechanical parameters differed between experts and non-experts using the same device with the same moments of inertia. Range of movement was higher in expert than in non-expert subjects only in YY devices. Experts achieved higher values using CP and YY devices in squat exercises than non-experts, except for eccentric peak force for YY. Previous experience in the use of RIDs will influence the results obtained in squat exercises.  Resumen. Se ha mostrado que la experiencia previa en el uso de dispositivos de inerciales rotatorios (RIDs) aumenta la respuesta del rendimiento de forma aguda El objetivo de este estudio fue examinar las diferencias en perfiles cinéticos y cinemáticos entre atletas con o sin experiencias en el uso de diferentes RIDs. Treinta y nueve hombres sanos realizaron un test incremental en el ejercicio de media sentadilla en dos RIDs diferentes: un dispositivo de eje horizontal con forma cilíndrica (YY) y otro de eje vertical y forma cónica (CP). Los participantes se agruparon en función de la experiencia en el uso de los dispositivos de inercia rotacional. Se analizaron el tiempo, la velocidad pico, la fuerza pico, el tiempo para alcanzar la fuerza pico, la fuerza promedio, el impulso y el rango de movimiento con el objetivo de determinar diferencias entre los grupos. Varios parámetros biomecánicos difirieron entre expertos y no expertos al usar el mismo dispositivo con los mismos momentos de inercia. El rango de movimiento fue mayor en los sujetos expertos que en los no expertos solo en los dispositivos YY. Los expertos lograron valores más altos usando dispositivos CP e YY en ejercicios de sentadilla que los no expertos, excepto por la fuerza pico excéntrica para YY. La experiencia previa en el uso de RIDs influirá en los resultados obtenidos en los ejercicios de sentadilla.

High intraset variability has been considered as a potential aid in the treatment of tendinopathy by producing forces in variable and unpredictable contexts that allow the athlete to return to sport pain free. The aim of this study was to compare the intraset variability in force profiles between different rotational inertia devices (RIDs) during concentric and eccentric (ECC) phases of movement and between different moments of inertia. Thirty-nine men performed a half-squat incremental test on 2 different RIDs: a horizontal cylinder and a vertical cone-shaped axis. Intraset variabilities in vertical force and velocity were analyzed using average coefficients of variation. RID squat exercise produced force intraset variability. The ECC phase of the movement showed more intraset variability in force output than the concentric phase. ECC vertical cone-shaped shaft showed a higher intraset variability in force than ECC horizontal cylinder-shaped shaft. This study demonstrated that using an RID to provide resistance in squat training of athletes produced a high intraset variability in the application of force.