The Effects of Repetitive Drop Jumps on Impact Phase Joint Kinematics and Kinetics

Abstract

The purpose of the study was to investigate the effects of fatigue on lower extremity joint kinematics, and kinetics during repetitive drop jumps. Twelve recreationally active males (n= 6) and females (n= 6) (nine used for analysis) performed repetitive drop jumps until they could no longer reach 80% of their initial drop jump height. Kinematic and kinetic variables were assessed during the impact phase (100 ms) of all jumps. Fatigued landings were performed with increased knee extension, and ankle plantar flexion at initial contact, as well as increased ankle range of motion during the impact phase. Fatigue also resulted in increased peak ankle power absorption and increased energy absorption at the ankle. This was accompanied by an approximately equal reduction in energy absorption at the knee. While the knee extensors were the muscle group primarily responsible for absorbing the impact, individuals compensated for increased knee extension when fatigued by an increased use of the ankle plantar flexors to help absorb the forces during impact. Thus, as fatigue set in and individuals landed with more extended lower extremities, they adopted a landing strategy that shifted a greater burden to the ankle for absorbing the kinetic energy of the impact.

Weight-Bearing Dorsiflexion Range of Motion and Landing Biomechanics in Individuals With Chronic Ankle Instability

“…29 They performed 3 to 5 practice trials until they were comfortable with the drop-landing task. We also informed participants that a successful landing trial required them to drop down on the force plate without propelling forward, avoid contact with the ground on the uninvolved foot, maintain the upper extremities folded across the chest, land with the entire foot on the force plate, and avoid any subsequent hops or sliding of the foot.…”

Methodological considerations of task and shoe wear on joint energetics during landing

“…Landing is consistent with the type of movement often observed at the time of acute joint injury (Boden et al, 2000;Olsen et al, 2004), and is a common laboratory research model used to understand the influence of potential risk factors associated with injury; for example, sex (Decker et al, 2003;Schmitz and Shultz, 2010;Shultz et al, 2009), joint laxity , and fatigue (Weinhandl et al, 2011), among others, on neuromechanical landing strategies. Using a landing research model, energetic analyses specifically examines the work done on/by the extensor muscles through integration of net joint powers (McNitt-Gray, 1993), which provides insight into the global biomechanical strategies that individuals may use to decelerate the body and dissipate impact forces (Zhang et al, 2000).…”

Reliability and fatigue characteristics of a standing hip isometric endurance protocol

“…In order to induce fatigue in the lower extremity, researchers have used various methods such as isokinetic (Sangnier and Tourny-Chollet, 2007), isometric (Katakura et al, 2011), sports-specific and treadmill protocols (Quammen et al, 2012;Weinhandl et al, 2011). These protocols are then used to detect eccentric, concentric or isometric strength differences and/or biomechanical changes in functional tasks such as running, cutting, jumping or landing before and after fatigue (Kallenberg et al, 2007;Katakura et al, 2011;Quammen et al, 2012;Sangnier and Tourny-Chollet, 2008;Weinhandl et al, 2011).…”

“…In order to induce fatigue in the lower extremity, researchers have used various methods such as isokinetic (Sangnier and Tourny-Chollet, 2007), isometric (Katakura et al, 2011), sports-specific and treadmill protocols (Quammen et al, 2012;Weinhandl et al, 2011). These protocols are then used to detect eccentric, concentric or isometric strength differences and/or biomechanical changes in functional tasks such as running, cutting, jumping or landing before and after fatigue (Kallenberg et al, 2007;Katakura et al, 2011;Quammen et al, 2012;Sangnier and Tourny-Chollet, 2008;Weinhandl et al, 2011). Fatigue onset has been determined several ways through either task failure (Carcia et al, 2005;Quammen et al, 2012;Weinhandl et al, 2011), percent decline in strength (Carcia et al, 2005;Katakura et al, 2011;Sangnier and Tourny-Chollet, 2007), a fatigue ratio equation (Sangnier and Tourny-Chollet, 2007), 90% maximum age-calculated heart rate, VO 2 max curve plateau, greater than 1.1 respiratory quotient (Quammen et al, 2012), significant increases in EMG amplitude or significant decreases in mean or median frequency (Jacobs et al, 2007;Kallenberg et al, 2007;Katakura et al, 2011).…”