title: Shock and impact reduction in moderate and strenuous landing activities.
abstract: Shock reduction has been well studied in moderate activities such as walking and running. However, there is a clear lack of research concerning shock wave transmission and reduction in more strenuous landing activities. In this study, we examined the impact of shock transmission and reduction in landing activities with varied mechanical demands. Ten active males were recruited for the study. They performed five successful step-off landing trials from each of five heights: 30, 45, 60, 75, and 90 cm. Right sagittal kinematics, ground reaction forces, and acceleration were recorded simultaneously. Impact frequencies were analysed using a discrete Fast Fourier Transform and power spectral density was computed. Increased range of motion for the ankle, knee, and hip joints was observed at higher landing heights. The peaks of the vertical ground reaction force, forehead and tibial accelerations, and eccentric muscle work by lower extremity joints were increased with increased landing heights. The peak head power spectral density was severely attenuated at higher frequencies but the peak tibia power spectral density did not demonstrate this trend. Shock reduction showed increased reduction at higher frequencies, but minimal changes across five landing heights. Unlike the responses observed for walking and running, the shock reduction did not show significant improvement with elevated mechanical demands.
authors.affiliation: Biomechanics/Sports Medicine Laboratory, Department of Exercise, Sport and Leisure Studies, The University of Tennessee, 1914 Andy Holt Ave., Knoxville, TN 37996, USA. szhang@utk.edu
authors.forename: Songning
authors.initials: S
authors.lastname: Zhang
authors.forename: Timothy R
authors.initials: TR
authors.lastname: Derrick
authors.forename: William
authors.initials: W
authors.lastname: Evans
authors.forename: Yeon-Joo
authors.initials: YJ
authors.lastname: Yu
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena; D006801:Humans; D035002:Lower Extremity / Q000502:physiology*; D008297:Male; D016059:Range of Motion, Articular; D013177:Sports / Q000502:physiology*; D013314:Stress, Mechanical