Considerations for single and double leg drop jumps: bilateral deficit, standardizing drop height, and equalizing...

Area of Science:

• Biomechanics
• Exercise Physiology
• Sports Science

Background:

• Bilateral deficit, where limb force is less during bilateral than unilateral contractions, is well-documented but not universal.
• Its presence is task-dependent, more common in dynamic than isometric actions, with reduced fast-twitch motor unit activation often cited as a mechanism.
• Understanding bilateral deficit in elite athletes is crucial for optimizing training and performance.

Purpose of the Study:

• To investigate bilateral deficit in elite power and endurance athletes using comparable single-leg and double-leg drop jumps.
• To determine if elite power athletes exhibit a greater bilateral deficit than elite endurance athletes.
• To establish consistent methodologies for assessing bilateral deficit in dynamic jumping tasks.

Main Methods:

• Seven elite power athletes and seven elite endurance athletes participated.
• Single-leg and double-leg drop jumps were performed from various heights, equalizing limb loading (height, energy, momentum).
• Force and motion data were collected at 800 Hz to calculate bilateral deficit for jump height, peak concentric force, and peak concentric power.

Main Results:

• Power athletes exhibited a significantly greater bilateral deficit in jump height and peak power (P < .05).
• Endurance athletes generally displayed a bilateral surfeit, potentially confounding direct comparisons of motor unit activation.
• Equalizing limb loading by impulse per leg was identified as the most appropriate method, achievable with brief coaching.

Conclusions:

• Elite power athletes demonstrate a more pronounced bilateral deficit in dynamic jumping tasks, potentially linked to a higher proportion of fast-twitch motor units.
• Endurance athletes may experience a bilateral surfeit, highlighting the importance of athlete type in bilateral deficit research.
• Standardized protocols, like equalizing impulse per leg, are essential for consistent bilateral deficit assessment in dynamic activities.