Considerations for Single and Double Leg Drop Jumps: Bilateral Deficit, Standardizing Drop Height, and Equalizing Training Load

Abstract

Bilateral deficit is well documented; however, bilateral deficit is not present in all tasks and is more likely in dynamic activities than isometric activities. No definitive mechanism(s) for bilateral deficit is known but an oft cited mechanism is lower activation of fast twitch motor units. The aim of this study was to produce comparable and consistent one and two legged drop jumps to examine bilateral deficit in elite power athletes and elite endurance athletes. Seven power athletes and seven endurance athletes performed single and double leg drop jumps from a range of heights that equalized loading per leg in terms of: height dropped, energy absorbed, and momentum absorbed. Force and motion data were collected at 800 Hz. Bilateral deficit for jump height, peak concentric force, and peak concentric power were calculated. Power athletes had a significantly greater (P< .05) bilateral deficit for jump height and peak power, possibly due to power athletes having more fast twitch motor units, however, endurance athletes generally had a bilateral surfeit which could confound this inference. Results indicate that equalizing loading by impulse per leg is the most appropriate and that a consistent drop height can be obtained with a short 10 minute coaching session.

Bilateral Deficit During Jumping Tasks: Relationship With Speed and Change of Direction Speed Performance

“…In essence, when left and right limbs were summed and still could not exceed the bilateral score, this demonstrates how challenging unilateral fast stretch-shortening cycle activities are. This is supported by Pain (30) who showed that both endurance and power-based athletes showed a BLF of -3.8 to -13.8% in power during the DJ test. Thus, with a wide variation in BLD scores across tests, it is suggested that this phenomenon is investigated with multiple metrics for each test.…”

“…Subjects were also told to maintain full extension throughout the lower-body during the flight phase of the jump. This was to ensure that dropping and jumping procedures were standardized, in line with research conducted by Pain (30). Any deviation from these instructions resulted in a void trial and the trial was retaken Bilateral and Unilateral Standing Broad Jump (SBJ).…”

“…Thus, a true examination of the BLD is only possible when comparable bilateral and unilateral tasks have been completed (e.g., bilateral and unilateral countermovement jumps [CMJ]). The presence of the BLD has been demonstrated during isometric (5,6,18,24,28,29), isokinetic (8,12,13,19,24,40), explosive (4,9,10,30,31,33,39,40) and sport-related motor tasks (7). However, speculation still exists as to the underlying mechanisms responsible for this phenomenon.…”

A Comparison of Bilateral vs. Unilateral-Biased Strength and Power Training Interventions on Measures of Physical Performance in Elite Youth Soccer Players

“…Bilateral and Unilateral Drop Jumps (DJ). Subjects performed the jumps using a contact mat (Just Jump system, Probotics, Huntsville, Alabama, USA) and started by standing on a box of 30 cm (bilateral) or 15 cm (unilateral) selected as the chosen height to drop from based on previous research (24). With hands fixed on hips throughout the duration of the test, subjects stood on the designated test leg and were instructed to step off the box and land on the contact mat below, with either both legs or one leg depending on the test measure in question.…”

Bilateral deficit: relationships with training history and functional performance

“…Whilst these investigations underline that the magnitude and existence of BLD may be of importance for athletes and practitioners attempting to maximise physical performance, these studies utilised only jumping assessments of BLD. Examination of literature reveals a range of tests used to assess BLD (Škarabot, et al, 2016), with BLD being demonstrated during isometric (Howard & Enoka, 1991;Magnus & Farthing, 2008;Botton, et al, 2013), isokinetic (Brown, Whitehurst, Gilbert, Findley, & Buchalter, 1994;Dickin & Too, 2006), and explosive (Buckthorpe, Pain, & Folland, 2013;Challis, 1998;Pain, 2014) tasks. Furthermore, a large number (e.g.…”