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Speed/Power Development

(33) THE IMPACT OF LOAD ON THE FORCE-TIME CHARACTERISTICS OF THE HEXAGONAL BARBELL JUMP IN RESISTANCE-TRAINED MEN

Thursday, July 11, 2024
2:00 PM – 3:30 PM East Coast USA Time
Location: Exhibit Hall
Abstract Details:

Purpose: To examine the impact that load has on the force-time characteristics of the static hexagonal barbell jump (HEXJ).

Methods: 20 resistance-trained men (age = 23.5 ± 3.0 years, height = 175.1 ± 8.7 cm, body mass 79.6 ± 11.8 kg, relative one repetition maximum back squat = 1.90 ± 0.28 kg/kg) participated in two separate testing sessions. The first session was used to assess the relative strength of the subjects and to familiarize them with the HEXJ exercise. The second session required the subjects to perform unloaded HEXJ repetitions as well as repetitions with loads corresponding to 20, 40, 60, 80, and 100% of their body mass (BM). Because each load rested on the floor, HEXJ repetitions required the subjects to squat down to the barbell to grip the handles, assume a knee angle of approximately 90° ± 5°, and hold a quiet standing period of at least one second before receiving a countdown prior to each jump. Two jumps were performed at each load on a force platform and the force-time data were used to determine propulsion duration net relative mean force (NetRelMF), duration (Dur), and net impulse (NetIMP). The average performance between repetitions at each load were used for statistical comparison. Each variable was compared between the HEXJ loads using a series of one-way repeated measures ANOVA with Bonferroni post hoc tests. In addition, Hedge’s g effect sizes were calculated to describe the magnitude of the differences between loads.

Results: There were significant differences in HEXJ propulsion NetRelMF, Dur, and NetIMP (all p< 0.001). Descriptive data and post hoc comparisons are shown in Table 1. The greatest NetRelMF was produced at 40% BM and trivial-moderate (g=0.15-1.10) differences between loads. The shortest propulsion Dur occurred at the lightest loads (0-20% BM) but small-very large (g=0.29-3.05) differences were present across the loading spectrum. Finally, similar NetIMP were produced at loads ranging from 60-100% BM and trivial-large (g=0.01-1.44) differences existed between loads.

Conclusions: The propulsion NetRelMF, Dur, and NetIMP were significantly impacted by the external load used during the HEXJ. Greater NetRelMF magnitudes were produced during the HEXJ with light-moderate loads (20-60% BM) while shorter propulsion Dur and larger NetIMP magnitudes were produced using lighter and heavier loads, respectively. PRACTICAL APPLICATIONS: Using lighter loads with the static HEXJ may provide a superior training stimulus for rapid jumps as the lighter loads have shorter Dur. Training with loads from 20-60% BM may provide a similar NetRelMF stimulus; however, heavier loads may need to be prescribed if the goal is to produce large NetIMP magnitudes. However, it is important that practitioners recognize that using percentages of BM has its shortcomings and that individuals may respond differently to the prescribed loads.

Acknowledgements: None