both for preventing injury and successfully performing an action. Time to stabilization (TTS) and dynamic postural stability index (DPSI) have been suggested as the measures of dynamic stability. 4 , 5 These measures can indicate the ability of a person to maintain his or her stability during
Kazem Malmir, Gholam Reza Olyaei, Saeed Talebian, Ali Ashraf Jamshidi and Majid Ashraf Ganguie
Cathleen Brown, Scott Ross, Rick Mynark and Kevin Guskiewicz
Functional ankle instability (FAI) is difficult to identify and quantify.
To compare joint position sense (JPS), time to stabilization (TTS), and electromy-ography (EMG) of ankle musculature in recreational athletes with and without FAI.
Case-control compared with t tests and ANOVAs.
Sports medicine research laboratory.
20 recreational athletes.
Main Outcome Measures:
Passive angle reproduction, TTS, and mean EMG amplitude of the tibialis anterior, peroneals, lateral gastrocnemius, and soleus muscles during single-leg-jump landing.
No differences in JPS or medial-lateral TTS measures between groups. Significantly longer anterior-posterior TTS (P < .05) in the unstable ankle group. The stable ankle group had significantly higher mean EMG soleus amplitude after landing (P < .05). No other significant differences were found for mean EMG amplitudes before or after landing.
Subjects with FAI demonstrated deficits in landing stability and soleus muscle activity during landing that may represent chronic adaptive changes following injury.
Doris Bolt, René Giger, Stefan Wirth and Jaap Swanenburg
Time-to-stabilization (TTS) is an example of an objective postural control measure. 3 An increased TTS after a jump has been found in athletes with chronic ankle instability (CAI) compared to uninjured controls. 2 In 27% of all ankle sprains, however, the underlying mechanism of injury is a fall
Scott E. Ross and Kevin M. Guskiewicz
Column-editor : Thomas W. Kaminski
Kathy Liu and Gary D. Heise
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.
Susan Miniello, Geoffrey Dover, Michael Powers, Mark Tillman and Erik Wikstrom
Previous studies have suggested that cryotherapy affects neuromuscu-lar function and therefore might impair dynamic stability. If cryotherapy affects dynamic stability, clinicians might alter their decisions regarding returning athletes to play immediately after treatment.
To assess the effects of lower leg cold immersion on muscle activity and dynamic stability of the lower extremity.
Within-subject time-series design with 1 pretest and 2 posttests.
A climate-controlled biomechanics laboratory.
17 healthy women.
20-minute cold-water immersion.
Main Outcome Measures:
Preparatory and reactive electromyographic activity of the tibialis anterior and peroneus longus and time to stabilization after a jump landing.
Preparatory activity of the tibialis anterior increased after treatment, whereas preparatory and reactive peroneus longus activity decreased. Both returned to baseline after a 5-minute recovery. Time to stabilization did not change.
Lower leg cold-immersion therapy does not impair dynamic stability in healthy women during a jump-landing task. Return to participation after a cryotherapy treatment is not contraindicated for healthy athletes.
Abbis H. Jaffri, Thomas M. Newman, Brent I. Smith, Giampietro L. Vairo, Craig R. Denegar, William E. Buckley and Sayers J. Miller
static assessment tasks, where the maintenance of static alignment of the body segments is the goal. 14 Differences in dynamic balance between CAI and uninjured populations have been demonstrated with this testing method. 14 Subjects with CAI took more time to stabilize than healthy subjects. 14
Dana M. Otzel, Chris J. Hass, Erik A. Wikstrom, Mark D. Bishop, Paul A. Borsa and Mark D. Tillman
found neither changes in dynamic postural control nor changes in muscle activity during preparatory or loading phases of the time-to-stabilization after a jump following a 6-minute session of WBV in individuals with CAI. A study by McBride et al 22 revealed increased triceps surae muscle force but no
Jacob T. Hartzell, Kyle B. Kosik, Matthew C. Hoch and Phillip A. Gribble
-S = sport subscale of FADI; SL = single leg; SPM = statistical parametric mapping; TTS = time to stabilization. Clinical Bottom Line There is weak evidence to support changes in sagittal plane knee kinematics at initial contact during a jump landing in individuals with CAI compared to healthy controls
Timothy C. Sell, Mita T. Lovalekar, Takashi Nagai, Michael D. Wirt, John P. Abt and Scott M. Lephart
KM . Time to stabilization: a method for analyzing dynamic . Athl Ther Today . 2003 ; 8 : 37 – 39 10.1123/att.8.3.37 34. Sell TC , Pederson JJ , Abt JP , et al . The addition of body armor diminishes dynamic postural stability in military soldiers . Mil Med . 2013 ; 178 ( 1 ): 76 – 81