Galiano, C, Pareja-Blanco, F, Hidalgo de Mora, J, and Sáez 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 ± 3.2 years; height: 175.8 ± 4.7 cm; body mass: 73.8 ± 10.8 kg) were randomly assigned to 2 groups: VL5 (n = 15) or VL20 (n = 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⁻¹ (AV > 1); average velocity for those loads that were moved slower than 1 m·s⁻¹ (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 ± 25.0 vs. 480.5 ± 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.

The aims of this study were to compare the force profile of using a horizontal cylinder-shaped axis or a vertical cone-shaped axis to provide resistance in rotary inertia devices, and to report the evolution of kinetic and kinematic variables in experienced athletes during a half-squat exercise. Twenty-two healthy active men participated in the assessment of time, peak velocity, peak force, time to reach the peak force, average force, impulse, and range of movement, during a half-squat incremental test performed on conical inertial device (CP) and on cylinder inertial device (YY). The analysis showed that YY during CON-ECC phased generates substantial higher peak_force, mean_force, impulse, time, and a lower peak_velocity, than CP. We never obtained eccentric overload for peak_force or mean_force. CP offers less resistance to accelerate-decelerate the movement with respect to YY, we need checking whether eccentric overload it is being produced, and the impulse was the only kinetic variable that was able to discriminate between the inertias and devices.

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.

Galiano, C, Nuñez, FJ, McErlain-Naylor, S, and Floria, P. Biomechanical insights into rotary inertial devices vs. traditional resistance training in half-squats: a comparative analysis of force, velocity, and displacement. J Strength Cond Res 39(5): 531–539, 2025—Although rotary inertial devices (RIDs) have been used in resistance training for many years, there is still limited knowledge of the specific biomechanics that distinguish them from traditional resistance training (TRT) methods. The aim of this study is to compare the serial data of force, velocity, and displacement over time in half-squats performed with both devices when the intensity is based on the concentric mean propulsive velocity (MPV). A total of 20 experienced subjects completed 3 sets of 6 half-squats using both RID and TRT. To ensure a similar load intensity, the concentric phase was matched according to the MPV. Measurements of vertical ground reaction force (vGRF), velocity, and displacement were taken for each repetition of the half-squat. The results showed that TRT exhibited a higher vGRF than RID during 0–57% of the concentric phase but a lower vGRF during 74–93% (p < 0.001). Eccentric vGRF was also higher for TRT throughout much of the eccentric phase (0–13%, 38–54%, and 68–100%, p < 0.001). Rotary inertial device demonstrated faster vertical velocity than TRT during 31–52% of the concentric phase and 1–40% of the eccentric phase (p < 0.001). However, during the latter part of the concentric phase (72–99%), TRT exhibited faster vertical velocity compared with RID. In addition, TRT resulted in a higher vertical position than RID at the end (67–100%) of the concentric phase (p = 0.036). Coaches should be aware of these biomechanical differences when prescribing resistance training with RID or TRT, as even with similar loads, distinct patterns in vGRF and velocity over time can lead to different effects on the athlete.

The objectives of this study were to compare the external and internal loads of transition games (TGs) without the opposition and TGs with different types of the opposition, and to assess their impact on a series of speed and strength tests. The external and internal loads of 18 young professional players (age: 14.79 ± 0.18 years; body height: 171.9 ± 6.5 cm; body mass: 62.1 ± 7.5 kg) were monitored in three TGs: 1 vs. 0 (no opposition; striker vs. goalkeeper), 1 vs. 1Front (defender between the goal and the striker), and 1 vs. 1Behind (defender behind the striker). Peak velocity (PeakV), distance covered (DC) above 24.0 km·h−1, 21.0–23.9 km·h−1, 18.0–20.9 km·h−1, 13.0–17.9 km·h−1, accelerations and decelerations above 2.5 m·s−2 and below −2.5 m·s−2 as well as the rate of perceived exertion (RPE) were obtained. Before and after each TG, vertical jump performance and sprint ability were assessed. PeakV and DC ≥24 km·h−1 differed among drills, showing superior outcomes in the 1 vs. 1Behind format. DC 21–23.9 km·h−1 showed significant differences among drills, with larger distances covered in the 1 vs. 0 format. The number of accelerations-decelerations was significantly different among drills. RPE response differed among drills, with larger values for 1 vs. 1Behind and 1 vs. 1Front formats. All post tests showed an effect on time response without significant group interaction. The 1 vs. 1Behind and 1 vs. 0 formats induce higher values for high speed, sprint and accelerations than the 1 vs. 1Front format, which shows better performance in decelerations.

Since most movement on the field require athletes to produce forces in variable and unpredictable context, the use of training programs based on identical repetitions of an exercise may not be optimal for movement transference. Therefore, the aim of this study was to analyze the effects of unexpected eccentric load variability during resistance training in team sport players. Sixty-three men randomly allocated in two experimental groups (Variable (VTG) and stable (STG) training group) and control group: (CG) volunteered to participate in this study. Experimental groups trained with the same average load of half-squat exercise twice a week for six weeks using rotary inertial devices (RIDs) with (VTG) and without (STG) an unexpected variability of the load. Squat force was measured for every session with force plates. Counter-movement jump (CMJ), sprint, and change of direction performances were measured pre and post-test. CMJ performance improved for VTG (p= 0.014; ES= 0.7) and STG (p = 0.005; ES= 0.79) but not for CG. Exposure to high eccentric forces with RIDs lead athletes to improve physical performance in the trained force-vector but, since RIDs induce in high levels of variability per se, increasing the level of variability of the exercise will not add benefits to physical performance and training outcomes.