Dual vs single force plate analysis of human drop jumping

Abstract

The aim was to develop a Drop Jump (DJ) protocol on dual force plate recordings (Dual Force Plate method: DFPM) to assess lower limb power production and quantify impact loading, and range of body center of mass (BCM) excursion during human DJ, and to examine if single-plate analysis (Reverse Integration Method: RIM) was a valid alternative. Nineteen male subjects performed DJs from an elevated platform (48 cm). Kinematic (BCM displacement and velocity, rebound jump height) and kinetic (BCM power, work, rate of force development (RFD), lower limb stiffness (LLS)) variables were obtained by force plate recording during the drop take-off phase (DFPM) and rebound phase (RIM, DFPM). DFPM and RIM did not differ at the group level for any outcome parameter. However, large intra-individual differences in BCM displacement were observed between DFPM and RIM (CV 9-10%) as well as for rebound jump height, LLS, and work performed on BCM (CV 9.8-14%). A majority of the remaining variables demonstrated low intra-individual variability between the two methods (r= 0.73-0.96, CV 1-5%). In conclusion, No systematic differences were revealed between DFPM and RIM, suggesting that RIM is a valid approach for assessing DJ performance. Substantial between-method intra-individual variability was noted for key outcome parameters.