Dynamic stability is often measured by time to stabilization (TTS), which is calculated from the dwindling fluctuations of ground reaction force (GRF) components over time. Common protocols of dynamic stability research have involved forward or vertical jumps, neglecting different jump-landing directions. Therefore, the purpose of the present investigation was to examine the influence of different jump-landing directions on TTS. Twenty healthy participants (9 male, 11 female; age = 28 ± 4 y; body mass = 73.3 ± 21.5 kg; body height = 173.4 ± 10.5 cm) completed the Multi-Directional Dynamic Stability Protocol hopping tasks from four different directions—forward, lateral, medial, and backward—landing single-legged onto the force plate. TTS was calculated for each component of the GRF (ap = anterior-posterior; ml = medial-lateral; v = vertical) and was based on a sequential averaging technique. All TTS measures showed a statistically significant main effect for jump-landing direction. TTSml showed significantly longer times for landings from the medial and lateral directions (medial: 4.10 ± 0.21 s, lateral: 4.24 ± 0.15 s, forward: 1.48 ± 0.59 s, backward: 1.42 ± 0.37 s), whereas TTSap showed significantly longer times for landings from the forward and backward directions (forward: 4.53 ± 0.17 s, backward: 4.34 0.35 s, medial: 1.18 ± 0.49 s, lateral: 1.11 ± 0.43 s). TTSv showed a significantly shorter time for the forward direction compared with all other landing directions (forward: 2.62 ± 0.31 s, backward: 2.82 ± 0.29 s, medial: 2.91 ± 0.31 s, lateral: 2.86 ± 0.32 s). Based on these results, multiple jump-landing directions should be considered when assessing dynamic stability.
Kathy Liu and Gary D. Heise
Sean J. Maloney, Joanna Richards, and Iain M. Fletcher
, Dugan E . Application of strength diagnosis . Strength Cond J . 2002 ; 24 ( 5 ): 50 – 59 . doi:10.1519/00126548-200210000-00014 10.1519/00126548-200210000-00014 16. Flanagan EP , Ebben WP , Jensen RL . Reliability of the reactive strength index and time to stabilization during depth jumps
John R. Harry, Max R. Paquette, Brian K. Schilling, Leland A. Barker, C. Roger James, and Janet S. Dufek
reactive strength index and time to stabilization during depth jumps . J Strength Cond Res . 2008 ; 22 ( 5 ): 1677 – 1682 . PubMed ID: 18714215 doi:10.1519/JSC.0b013e318182034b 18714215 10.1519/JSC.0b013e318182034b 19. Markwick WJ , Bird SP , Tufano JJ , Seitz LB , Haff GG . The intraday
Prasanna Sritharan, Luke G. Perraton, Mario A. Munoz, Peter Pivonka, and Adam L. Bryant
trimmed to 2 seconds, the minimum time allowed to successfully complete a landing, and defined as the total time to stabilization . The landing phase was defined as the time period from foot strike to peak knee flexion angle. All subsequent time until 2 seconds elapsed was defined as the stabilization