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The preferred balance leg absorbs more energy than the preferred striking leg in single leg landings Steve McCaw, Mitch Waller, Kevin Laudner & Pete Smith
Landing • Landing = moving body to rest • Integral to many sport activities and Activities of Daily Living • Implicated in a variety of lower extremity injury • Ankle sprain • Osteoarthritis • ACL damage • A good model to investigate • Mechanism(s) of injury • Mechanism of energy absorption • Interesting phenomenon on its’ own.
Landing Research Perform two leg landing, only one leg analyzed • “Dominant Leg” • Madigan & Pitcoe, J EMG & Kinesiology, 2003 • Effects of fatigue on landing biomechanics • Pollard et al, Clin J Sport Med, 2006 • Pre and post season evaluation of injury training • “Preferred Limb” (lead leg when drop jumping) • Kulas et al, J App Biomech, 2006 • A, K & H energy absorption and LE impedance Bilateral comparisons of Lower Extremities • “Right” vs “Left” • Schot et al, MSSE, 1994 • Quantify bilateral asymmetry • “Dominant” vs “non-dominant” • Hewett et al, J Bone Joint Surg, 2004 • Investigate MS changes with maturation
Hewett, Meyer & Ford Increased maximum valgus angle reflects decreased neuromuscular control
General Concept of Lateral Preference • Guiard, Y. (1987). Asymmetric Division of Labor in Human Skilled Bimanual Action: The Kinematic Chain as a Model. J Motor Behavior, 19:4:486-517. • Unimanual tasks* • Dart throwing, brushing teeth • Bimanually symmetric • In phase: Rope skipping, weightlifting • Out of phase: rope climbing • Bimanually asymmetric • Dealing cards, cursive writing • Individuals exhibit a preference for one of the two possible ways of assigning two roles to two hands
Dynamic Dominance Hypothesis • Sainburg, RL. (2005). Handedness: differential specialization for control of trajectory and position. Exerc Sport Sci Rev,33:4:206-213. • Hemispheres /limb systems specialized for complementary functions • Dominant side: controlling limb trajectory dynamics • Non-dominant side: controlling limb position • Non-dominant arm slightly more accurate • Dominant arm used less elbow muscle torque
Applicable to Lower Extremity? • Nunome et al, 2006. Segmental dynamics of soccer instep kicking with the preferred and non-preferred leg. J Sports Science, 24:5:529-541 • Highly skilled players achieved a well-coordinated inter-segmental motion for both the preferred and non-preferred leg • Faster leg swing observed for the preferred leg • result of larger muscle moment
Purpose Compare LE kinetics and energetics between single-leg drop landings onto preferred striking & balance legs Hypothesis Preferred balance limb will absorb more energy than the preferred striking limb
21 college-age female volunteers 21.5±2.2 y 1.64 ± 0.08 m 65.2 ± 8.2 kg Regular lander Free of LE traumas 10 trials R & L leg Random order “Land comfortably” 32cm bench Force Platform (1000 Hz ) 3 cameras (200 Hz) Sagittal plane kinematics Inverse dynamics for JMF JMP = JMF •ω Paired t-tests (α = .05) Methods
Modified Waterloo Handedness Questionnaire • Identify preferred “action” leg in bilaterally asymmetric tasks • Strong agreement with ball “striking” leg
Joint Position Preferred Striking Leg Preferred Balance Leg Joint Angle (degrees) Time to Max Knee Flexion (%)
Joint Torque Preferred Striking Leg Preferred Balance Leg Joint Torque (N·m•kg-1 ) Time to Upright Stance(%)
JointPower Preferred Striking Leg Preferred Balance Leg Joint Mechanical Power (W/kg) Time to Upright Stance(%)
Percent Energy Absorption Hip ± SD% Hip±SD% Relative joint contributions will be significantly different. Knee±SD% Knee ± SD% Ankle±SD% Ankle ± SD% Preferred Striking Preferred Balance
Conclusions • Bilateral Preference Concept [Guiard, 1987] & Dynamic Dominance Hypothesis [Sainburg, 2005] may apply to lower extremity • PBL better energy absorber than PSL • LE comparisons should identify analyzed limb according to preference rather than dominance • Appropriate limb terminology should be utilized