Understanding Jump Landing as an Oscillating System: A Model-based Approach of Balance and Strength Analyses

Prospective Study on Dynamic Postural Stability in Youth Competitive Alpine Skiers: Test-Retest Reliability and Reference Values as a Function of Sex, Age and Biological Maturation

“…The ground reaction force data were filtered using a second order Butterworth low pass filter with a cut-off frequency of 200 Hz. All trial data were reduced to a 3 s interval of the landing phase after the hurdle jump, beginning at the time of initial ground contact, which was defined as the point in time where the vertical GRF crossed a threshold of 25 N. Absolute DPSI was then calculated over the corresponding interval as a composite of force in all three directions, which are mean square deviations assessing fluctuations around a zero point, with the formula according to Hellmers et al (2017) : n represents the number of data points (i.e., 2000 Hz × 3 s = 6000 frames in our study), F BW is the body weight force, and F x , F y , F z are the forces in the anteroposterior (x), mediolateral (y) and vertical (z) directions. The relative DPSI was determined by dividing the absolute DPSI by body weight force.…”

“…A suitable measure to quantify the balance performance during DJSLL could be found in the Dynamic Postural Stability Index (DPSI), which has already been described several times in previous studies ( Goldie et al, 1989 ; Wikstrom et al, 2005 ; Hellmers et al, 2017 ). The DPSI is a measure that determines a person’s ability to regain balance while transitioning from a dynamic to a static state of single-leg stabilization.…”

“…Over a 3-s period after impact, the fluctuation of ground reaction force (GRF) around the origin during landing is determined, thereby quantifying neuromuscular control in the anteroposterior, mediolateral, and vertical directions ( Wikstrom et al, 2005 ). Previous studies assessed dynamic postural control primarily during basic stance positions, counter movement jumps or single leg landings after two-leg vertical jumps ( Goldie et al, 1989 ; Wikstrom et al, 2005 ; Hellmers et al, 2017 ) and reported the latter test to be highly reliable (intraclass correlation coefficient = 0.96) and very precise (SEM = 0.03) ( Wikstrom et al, 2005 ).…”

Postural Balance Control in Sport and Exercise

“…A suitable measure to quantify the balance performance during DJSLL could be found in the Dynamic Postural Stability Index (DPSI), which has already been described several times in previous studies (Goldie et al, 1989;Wikstrom et al, 2005;Hellmers et al, 2017). The DPSI is a measure that determines a person's ability to regain balance while transitioning from a dynamic to a static state of single-leg stabilization.…”

“…Over a 3-s period after impact, the fluctuation of ground reaction force (GRF) around the origin during landing is determined, thereby quantifying neuromuscular control in the anteroposterior, mediolateral, and vertical directions (Wikstrom et al, 2005). Previous studies assessed dynamic postural control primarily during basic stance positions, counter movement jumps or single leg landings after two-leg vertical jumps (Goldie et al, 1989;Wikstrom et al, 2005;Hellmers et al, 2017) and reported the latter test to be highly reliable (intraclass correlation coefficient = 0.96) and very precise (SEM = 0.03) (Wikstrom et al, 2005).…”