(35) FORCE-TIME DIFFERENCES BETWEEN THE STATIC HEXAGONAL BARBELL JUMP AND SQUAT JUMP IN RESISTANCE-TRAINED MEN

Abstract Details:

Purpose: To examine the differences in force-time characteristics between the static hexagonal bar jump (HEXJ) and squat jump (SJ) performed with different percentages of body mass (BM).

Methods: 20 men (age = 23.5 ± 3.0 years, height = 175.1 ± 8.7 cm, BM = 79.6 ± 11.8 kg) participated in two separate testing that required the subjects to perform either static HEXJ or SJ repetitions using 0, 20, 40 60, 80 and 100% of their BM as loads. HEXJ and SJ repetitions were performed on a force platform from a static starting position with the respective barbells resting on the floor or on boxes, respectively. Subjects either squatted down to the barbell (HEXJ) or under the barbell (SJ) to assume a knee angle of approximately 90° ± 5° and held a quiet standing period of at least one second before receiving a countdown prior to each jump trial. Each jump was performed on a force platform and the raw force-time data were used to calculate propulsion net (above system weight) relative mean force (NETRELMF), duration (DUR), and net impulse (NETIMP). A series of 2 (exercise) x 6 (load) repeated measures ANOVA with Bonferroni post hoc tests were used to compare the force-time characteristics produced during the HEXJ and SJ performed at each BM load. Hedge’s g effect sizes were calculated to provide a measurement of the magnitude of the difference between exercises.

Results: There was a significant exercise x load interaction effect for NETIMP (p = 0.027) but not for NETRELMF (p = 0.056) or DUR (p = 0.055). In addition, there was a significant exercise main effect for NETRELMF (p = 0.010) and DUR (p < 0.001) as well as significant load main effects for both variables (p < 0.001). Descriptive statistics and post hoc analyses are displayed in Table 1. There were trivial-moderate differences in NETRELMF and NETIMP between the HEXJ and SJ. However, the differences between exercises ranged from small-large fur DUR.

Conclusions: On average, the SJ produced greater NETRELMF compared to the HEXJ; however, HEXJ DUR on average were greater than the SJ. Finally, although greater NETIMP were produced during the HEXJ compared to the SJ across the entire loading spectrum, the differences were not substantial. PRACTICAL APPLICATIONS: Both the HEXJ and SJ may provide an effective training stimulus for resistance-trained men. However, if the training goal is to maximize rapid force production, the SJ may be a superior alternative to the HEXJ. The load prescribed can have a significant impact on the force production characteristics of the HEXJ and SJ exercises and thus, loads should be chosen based on the sought after performance characteristic. Practitioners should however consider the limitations of using percentages of BM when prescribing loads as individuals may respond differently based on their relative strength characteristics.

Acknowledgements: None