This study aimed to clarify the differences between the horizontal single-leg rebound jump (HJ) and vertical single-leg rebound jump (VJ) in terms of three-dimensional joint kinetics for the take-off leg, while focusing on frontal and transverse plane movements. Eleven male track and field athletes performed HJ and VJ. Kinematic and kinetic data were calculated using data recorded with a motion capture system and force platforms. The hip abduction torque, trunk lateral flexion torque (flexion for the swing-leg side), hip external and internal torque, trunk rotational torque, and the powers associated with these torques were larger when performing HJ because of resistance to the impact ground reaction force and because of pelvic and posture control. Pelvic rotation was noted in HJ, and this was controlled not only by the hip and trunk joint torque from the transverse plane but also by the hip abduction torque. Therefore, hip and trunk joint kinetics in the frontal and transverse plane play an important role in a single-leg jump, regardless of the jumping direction, and may also play a more important role in HJ than in VJ.

We investigated the relationships between the lower-limb joint kinetic parameters of sprint running and rebound jump during the support phases in 16 male track and field athletes performing sprint running and rebound jump at maximal effort. Sprint running velocity and rebound jump index (i.e., jump height divided by contact time) during rebound jump were calculated. Lower-limb joint kinetic parameters (joint torque and power) during the support phases of these activities were calculated using a force platform and data from a high-speed video camera that recorded movements in the sagittal plane. No significant correlation was observed between sprint velocity and rebound jump index. However, significant correlations were observed between sprint running and rebound jump for mean ankle-joint torque and mean knee-joint torque in the eccentric and concentric phases, as well as for mean negative ankle-joint power and mean negative knee-joint power. These results suggest mechanical similarities in ankle-and kneejoint kinetic parameters, especially in the eccentric phase of sprint running and rebound jump, although such similarities were not observed for sprint velocity and rebound jump index.

The purpose of this study was to quantify the kinetics per leg during the one- and two-leg hang power clean using various loads. Nine male track and field athletes performed the one- and two-leg hang power clean on a force platform. The estimated one-repetition maximum was used for the one-leg hang power clean (OHPC), and the one-repetition maximum was used for the two-leg hang power clean (THPC). The loads used were 30%, 60%, and 90% during both trials. We calculated peak power, peak force, and peak rate of force development during the pull phase from the force-time data. The peak power and the peak force for all loads during the OHPC were statistically greater than during the THPC. The peak rates of force development at 60% and 90% during the OHPC were statistically greater than during the THPC. Additionally, the peak power at 90% was significantly less than at 60% during the THPC. These findings suggest that the OHPC at loads of 60% and 90% is a weightlifting exercise that exhibits greater explosive force and power development characteristics than the THPC.

AbstractThe present study was conducted to clarify points for attention, and to determine an eŠective method for the single-leg rebound-type jump (SRJ) and double-leg rebound-type jump (DRJ) in plyometrics, by investigating the joint kinematics and kinetics of the takeoŠ leg in the sagittal plane. Twelve male track andˆeld athletes (sprinters and jumpers) performed the SRJ and DRJ with maximal eŠort. Jumping motions in the sagittal plane were videotaped with a high-speed video camera (300 Hz), and ground reaction force was recorded with a force platform (1000 Hz). Kinematics and kinetics were calculated. To evaluate the force output characteristics for a single leg in the DRJ, the ground reaction force was divided into half, and the data were used to calculate the other kinetic parameters. The overall results of these analyses were as follows: 1. In the SRJ, the jump height for a single leg and the landing height for a single leg were higher than in the DRJ because of the higher mechanical power used during the eccentric and concentric phases.

Vertical (VDJ) and horizontal (HDJ) double-leg rebound jumps are used as plyometric exercises in direction-specific training regimens for various sports. We investigated the effects of jump direction on joint kinetics of the take-off legs in double-leg rebound jumps. Twelve Japanese male track and field athletes performed VDJ, 100% HDJ, 50% HDJ (50% of 100% HDJ distance), and 75% HDJ (75% of 100% HDJ distance). Kinematic and kinetic data in the sagittal plane were calculated using a force platform and high-speed video camera. Hip negative power during the eccentric phase decreased from VDJ to 50% HDJ (VDJ, −4.40 ± 4.25 W/kg; 50% HDJ, −0.83 ± 2.10; 75% HDJ, −0.33 ± 0.83; 100% HDJ, 0 ± 0), while hip positive power increased from VDJ to 100% HDJ (VDJ, 4.19 ± 2.73 W/kg; 50% HDJ, 9.37 ± 2.89; 75% HDJ, 11.15 ± 3.91; 100% HDJ, 18.51 ± 9.83). Knee negative power increased from VDJ to 75% HDJ (VDJ, −14.48 ± 7.67 W/kg; 50% HDJ, −18.98 ± 7.13; 75% HDJ, −21.57 ± 8.54; 100% HDJ, −23.34 ± 12.13), while knee positive power decreased from VDJ to 75% HDJ (VDJ, 23.18 ± 9.01 W/kg; 50% HDJ, 18.83 ± 5.49; 75% HDJ, 18.10 ± 5.77; 100% HDJ, 16.27 ± 6.22). Ankle joint kinetics remained unchanged. Differences in hip and knee joint kinetics between VDJ and HDJ were associated with direction control, becoming more pronounced as jump distance increased.