(30) USING BODY WEIGHT PERCENTAGES WITH ACCENTUATED ECCENTRIC DUMBBELL JUMPS DURING MULTIPLE SETS: PRELIMINARY FINDINGS

Purpose: To examine differences in force-time characteristics across multiple sets of accentuated eccentric loaded (AEL) countermovement (CMJ) and rebound jumps (RJ) with a prescribed load of 20% the subjects’ body weight (BW).

Methods: Six resistance-trained males (age: 27.3±5.4 years, body mass: 81.7±13.3 kg, height: 176.0±8.4 cm, relative one repetition maximum (1RM) back squat: 2.0±0.5 kg·kg^-1) and eight resistance-trained females (age: 22.3±2.2 years, body mass: 70.1±8.7 kg, height: 169.4±7.5 cm, relative 1RM back squat: 1.4 ± 0.3) participated in two testing sessions. The first session included a 1RM back squat and familiarization with AEL CMJ followed by RJ. During the following session, subjects performed three sets of an AEL CMJ with dumbbells equating to 20% of the subject’s BW followed by four consecutive RJ. Each set was performed on a force platform and the force-time data were used to calculate braking mean force (BMF) and duration (BDur) and propulsion mean force (PMF) and duration (PDur) for both the single CMJ and each of the four RJ performed within each set. The CMJ and average RJ were used for statistical analysis. A series of one-way repeated measures ANOVA tests were used to compare the CMJ and RJ braking and propulsion force-time characteristics across sets. In addition, Hedge’s g effect sizes were calculated to determine the magnitude of the differences between each set.

Results: AEL CMJ and average RJ force-time characteristics are displayed in Table 1. There were significant differences between sets for RJ BMF (p=0.009) and BDur (p=0.005). In contrast, there were no significant differences between sets for CMJ BMF (p=0.096), BDur (p=0.845), PMF (p=0.754), or PDur (p=0.854), but also not for RJ PMF (p=0.190) or PDur (p=0.148). Trivial to small effect sizes existed across sets for all the examined variables.

Conclusions: CMJ and propulsive RJ force-time characteristics were maintained across all three sets of AEL CMJ using 20% of the subject’s BW followed by four RJ. RJ braking characteristics were modified across the sets; however, these changes were trivial to small. Furthermore, there were no practically meaningful differences across sets for any variable as indicated by the effect sizes. PRACTICAL APPLICATIONS: AEL jumps may provide a novel stimulus for individuals with plyometric and resistance training experience compared to performing traditional CMJ. While there has been limited research suggesting an optimal load for prescribing these jumps, utilizing 20% of an individual’s body weight may contribute to improving CMJ and propulsive RJ force-time characteristics as they are maintained throughout multiple sets. Further research is necessary to examine the impact of different prescribed loads relative to an individual’s body weight across multiple sets to improve training prescription.

Acknowledgements: None