Effect of landing stiffness on joint kinetics and energetics in the lower extremity

Abstract

Ground reaction forces (GRF), joint positions, joint moments, and muscle powers in the lower extremity were compared between soft and stiff landings from a vertical thll 01'59 cm. Sott and stitf land~ngs had less than and greater than 90 degrees of knee flexion after floor contact. Ten trials of sagittal plane film and GRF data, sampled at 100 and 1000 Hz, were obtained from each of eight female athletes and two landing conditions. Inverse dynamics were performed on these data to obtain the moments and powers during descent (free fall) and floor contact phases. Angular impulse and work values were calculated from these curves, and the conditions were compared with a correlated t-test. Soft and stiff landings averaged 117 and 77 degrees of knee flexion. Larger hip extensor (0.010 vs 0.019 N.m .s. kg-'; P < 0.01) and knee flexor (-0.010 vs-0.013 N.m.s.kg-I; P < 0.01) moments were KINETICS AND ENERGETICS OF LANDING

Quality of functional movement patterns and injury examination in elite-level male professional football players

“…There is a significant amount of earlier international research that prove the high ratio of injuries in football (30,31,37,48) and the fact that these injuries most frequently occur in the lower extremities (20,21), where the largest single risk factor for the footballers consists of the non-contact injury of the anterior cruciate ligament (ACL) (1,22,59). Furthermore, the quality of movement patterns, especially the lower extremity patterns, is an important and modifiable factor that may influence the risk of ACL injury as well as play a critical role in injury mechanism (2,6,14). In order to reduce the frequency of these injuries, advice regarding prevention and rehabilitation is needed with actual strengthening programs for the treatment of the muscle imbalance, stretching exercises to moderate muscle stiffness, as well as proprioceptive programs for the improvement of balance and bodily movement (4,27,47).…”

Sagittal-Plane Trunk Position, Landing Forces, and Quadriceps Electromyographic Activity

“…Higher ground reaction forces are associated with a more erect or upright landing posture. 11,16 Females, who compose a population at heightened risk for ACL injury, 17,18 display a more erect posture during landing compared with males, as evidenced by more extended knee, 6,[19][20][21][22] hip, 6,[19][20][21][22] and trunk 19 positions. Not surprisingly, greater quadriceps electromyographic (EMG) activity 23 and ground reaction forces 21 have been reported in females than in males during landing.…”

The Effect of Foot Landing Type on Lower-extremity Kinematics, Kinetics, and Energy Absorption during Single-leg Landing

“…In forefoot landing, knee flexion from initial contact to peak vertical GRF was 13° and ankle dorsiflexion was 28.3°, whereas for rearfoot landing, knee flexion was 0.8° and ankle plantarflexion was 8.7°, which was consistent with our hypothesis that the two landing types would show differences in flexion of the lower-extremity joints. To effectively absorb the impact during landing, flexion needs to increase in each joint, and this has been reported to prevent injury from the impact being transferred to the body (Devita & Skelly, 1992;Yeow et al, 2010;Zhang et al, 2000). In other words, since the results of our study show greater knee and ankle flexion for forefoot landing, the knee extensors and ankle plantarflexors are able to continue absorbing energy, reducing the load acting on the joints; conversely, for rearfoot landing, more restricted flexion of the knee and ankle joints impairs the ability to properly absorb the impact of the GRF, which is larger than in forefoot landing, resulting in a higher risk of knee or ankle injury.…”