Between-limb asymmetry in kinetic and temporal characteristics during bilateral plyometric drop jumps from different heights

ABSTRACT

This study investigated the between-limb asymmetry in kinetic and temporal characteristics during bilateral plyometric drop jumps from different heights. Seventeen male basketball players performed drop jumps from 3 heights on two platforms in randomized orders. Vertical ground reaction force data were analysed with respect to the lead limb (i.e. the limb stepping off the raised platform first) and trail limb. Peak forces and loading rates of each limb were calculated. The absolute time differential between the two limbs at initial ground contact and takeoff were determined. The frequency of symmetrical landing and taking off with “both limbs together” were counted using 3 time windows. Results showed that the lead limb displayed higher peak forces and loading rates than the trail limb across all heights (p <.05). As drop height increased, the absolute time differentials decreased at initial ground contact (p <.001) but increased at takeoff (p =.035). The greater the preset time window, the more landings and takeoffs were classified as bilaterally symmetrical. In conclusion, higher drop heights allowed subjects to become more bilaterally symmetrical in the timing of landing but this reduction in temporal asymmetry did not accompany with any reduction in kinetic asymmetry.

KEYWORDS:

• Peak force
• loading rate
• initial contact
• takeoff
• ground reaction force
• time differential

Acknowledgments

The authors would like to thank Dr Yoong Ping Lim, Ms Lisa Noteboom, and Mr Lucas Nijman for their contribution during the pilot phase of this study.

Disclosure statement

Dr Thorsten Sterzing was an employee at Xtep (China) Co Ltd at the time of the study. There is no conflict of interest for all other authors.

Additional information

Funding

No external funding was received. The shoes worn by participants were provided by Xtep (China) Co Ltd.