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2022 Abstracts

Barbell kinematics and power with and without leg drive in the bench press lift.

Presenter: Lane Johnson
Authors: Lane Johnson, Ethan Del Toro, Carson Hopp, Loren Olsen, Bradley Mehew, Jake Rhea, Hannah Goodfellow
Faculty Advisor: Travis Ficklin
Institution: Dixie State University

In powerlifting, a bench press movement begins with a lifter laying supine on a bench with feet on the floor and arms extended to hold a loaded weightlifting bar above the lifter. The lifter allows the bar to descend to the chest under control, then presses the bar upward until full arm extension. One lifting technique is to use leg drive to push downward on the floor at the beginning of the upward portion of the movement. The purpose of this study was to determine if using leg drive increases performance over not using leg drive. Skilled lifters executed bench press lifts, with and without leg drive, using a load of 90% of One-Repetition Maximum (1RM). A 3D motion capture system was used to track bar position and force plates were used to measure ground reaction force (GRF). The vertical velocity and acceleration of the bar center of mass (CoM) were derived, and Newton’s law of acceleration was used to calculate time-series force applied to the bar by the lifter. Peak power and velocity for leg-drive lifts were compared to non-leg-drive lifts using paired t-tests (𝛼 = 0.05). There was a trend toward greater bar velocity and concentric power in leg-drive lifts (p = 0.064 and p = 0.063, respectively). Further, strong correlation between bar velocity and concentric power (r = 0.897), and moderate positive correlation of GRF to eccentric power (r = 0.358) were seen. GRF was weakly negatively correlated to bar velocity (r = -0.247) and moderately negatively correlated to concentric power (r = -0.449). Data collection is ongoing, with statistically significant differences between techniques in bar velocity and endpoint power expected by date of presentation.