(23) USING MOMENTUM TO OPTIMIZE LOADED JUMP TRAINING: A MODEL STATISTIC APPROACH

Strength coaches incorporate loaded jumps (LJ) into training program for their athletes due to the simplicity of the movement and because they are thought to be specific to the athletic task of vertical jumping. Maintaining power during the propulsive phase is one of the primary considerations when programming LJ. However, maintaining power is challenging because it is heavily reliant on maintaining propulsive velocity. Recently, it has been proposed that momentum may be a more robust metric for assessing LJ performance due to the mechanical relationship of velocity with system mass when calculating momentum.

Purpose: The purpose of this study was to assess differences in peak power and momentum between unloaded vertical jumps and loaded jumps completed with a straight barbell and a hexagonal barbell in a light (20% of back squat 1-repetition maximum [1RM]) and heavy (60% 1RM) conditions.

Methods: Fifteen males (age: 23.3±3.5yr, mass: 84.7±16.7kg, height: 177.9±7.0cm, 1RM: 157.7±34.1kg) and five females (age: 23.1±5.4yr, mass: 72.5±4.2, height: 166.0±8.9cm, 1RM: 123.7±9.8kg) completed this study. All participants were recreationally active and had not sustained any significant lower body injury in the previous two years. Participants completed two visits to the laboratory, and each visit was separated by 3-7 days. During the first visit, anthropometric data was recorded, and participants completed the 1RM protocol for the back squat. During the second visit, participants completed four successful vertical jump trials in each of the following conditions: no added load (UL), straight bar with 20% of back squat 1RM (SBJ20), hexagonal barbell with 20% load (HBJ20), straight barbell with 60% load (SBJ60), and hexagonal barbell with 60% load (SBJ60).  Each trial was separated by one minute of rest, and no specific instructions were given on how to complete each jump. Kinetic data for each trial was collected using dual force platforms (OPT464508; Advanced Mechanical Technology, Inc., Watertown, MA). Jump height (JH), takeoff velocity (TOV), momentum (MOM), and peak power during the concentric phase of the countermovement (PP) were calculated. A one-way, within-subjects repeated measures ANOVA was used to assess variables of interest at the group level. The Model Statistic was used to assess individual differences between UL and loaded conditions.

Results: JH, TOV, and PP were significantly lower in the loaded conditions compared to UL in both the group- and individual-level analyses. Group-level analysis revealed that MOM was only lower in both SBJ60 and HBJ60 compared to UL. The Model Statistic revealed that four and nine participants increased MOM in SBJ20 and HBJ20 conditions, respectively. Furthermore, four participants did not experience a decrease in MOM in each of the 60% conditions compared to UL.

Conclusions: Based on the combined group- and individual-level results, MOM may be a more robust metric than PP when assessing LJ performance in athletes because substantial decreases in velocity can be offset by accounting for the increased external load. PRACTICAL APPLICATION: MOM may be a better metric for practitioners because it allows for a wider loading range for their individual athletes. When appropriate, researchers should also consider utilizing the Model Statistic to supplement research findings due to its similarities to applied strength settings.  

Acknowledgements: None.