(39) COMPARING FORCE-TIME CHARACTERISTICS BETWEEN MEN AND WOMEN DURING ACCENTUATED ECCENTRIC DUMBBELL COUNTERMOVEMENT JUMPS USING VARIOUS LOADING SCHEMES

Purpose: To compare the force-time characteristics of accentuated eccentric loaded (AEL) countermovement jumps (CMJ) between males and females using different percentages of body weight. Methods: Resistance-trained men (n = 14, age = 24.9 ± 4.7 years, height = 174.1 ± 6.8 cm, body mass = 77.6 ± 10.9 kg, relative one repetition maximum [1RM] back squat = 2.0 ± 0.4 kg/kg) and women (n = 14, age = 22.4 ± 1.8 years, height = 164.6 ± 6.3 cm, body mass = 69.6 ± 7.7 kg, relative 1RM back squat = 1.4 ± 0.2 kg/kg) participated in two separate testing sessions. The first session required the subjects to complete a 1RM back squat protocol and familiarization trials of the AEL CMJ. The following session required each subject to perform AEL CMJ with dumbbells equating to 10%, 20%, and 30% of their body weight. The jumps were performed on a force platform and the force-time data were used to calculate CMJ braking mean force (BMF) and duration (BD) as well as propulsion mean force (PMF) and duration (PD). A series of 2 (sex) x 3 (load) repeated measures ANOVA were used to compare CMJ BMF, BD, PMF, and PD between the male and female subjects. In addition, Hedge’s g effect sizes were calculated to examine the magnitude of the differences for each variable. Results: There was a significant sex x load interaction effect for PD (p=0.003; g = 0.08 – 0.46) but not for BMF (p = 0.103; g = 0.26-0.81), BD (p = 0.081; g = 0.01-0.48), or PMF (p = 0.327; g = 1.20-1.36). However, post analysis revealed no significant differences in PD between sexes at any load (p > 0.05). There was a sex main effect difference for load-averaged PMF favoring the men (p = 0.001); however, there were no other differences between sexes for the remaining variables (p > 0.05). Finally, there was a significant load main effect for BMF, BD, PMF, and PD (all p < 0.001). Conclusions: There were significant and large differences favoring the men for PMF during AEL CMJ. Although not statistically significant, the men also produced BMF magnitudes that were small-moderately greater than the women. In contrast, there were non-significant, trivial-small differences between men and women for BD and PD. The external load may have a significant impact on the force-time characteristics produced during AEL CMJ. Practical Applications: Resistance-trained men may produce more peaked impulses during the braking and propulsion phases of AEL CMJ compared to resistance-trained women as characterized by greater forces during similar phase durations. Strength and conditioning practitioners may implement AEL CMJ with both men and women; however, they must consider the relative strength of each individual as they may respond to various percentages of body weight in a unique manner. Acknowledgements: None