title: Time to stabilization in single leg drop jump landings: an examination of calculation methods and assessment of differences in sample rate, filter settings and trial length on outcome values.
abstract: Time to stabilization (TTS) is the time it takes for an individual to return to a baseline or stable state following a jump or hop landing. A large variety exists in methods to calculate the TTS. These methods can be described based on four aspects: (1) the input signal used (vertical, anteroposterior, or mediolateral ground reaction force) (2) signal processing (smoothed by sequential averaging, a moving root-mean-square window, or fitting an unbounded third order polynomial), (3) the stable state (threshold), and (4) the definition of when the (processed) signal is considered stable. Furthermore, differences exist with regard to the sample rate, filter settings and trial length. Twenty-five healthy volunteers performed ten 'single leg drop jump landing' trials. For each trial, TTS was calculated according to 18 previously reported methods. Additionally, the effects of sample rate (1000, 500, 200 and 100 samples/s), filter settings (no filter, 40, 15 and 10 Hz), and trial length (20, 14, 10, 7, 5 and 3s) were assessed. The TTS values varied considerably across the calculation methods. The maximum effect of alterations in the processing settings, averaged over calculation methods, were 2.8% (SD 3.3%) for sample rate, 8.8% (SD 7.7%) for filter settings, and 100.5% (SD 100.9%) for trial length. Differences in TTS calculation methods are affected differently by sample rate, filter settings and trial length. The effects of differences in sample rate and filter settings are generally small, while trial length has a large effect on TTS values.
authors.affiliation: MOVE Research Institute Amsterdam, Faculty of Human Movement Sciences, VU University Amsterdam, Amsterdam, The Netherlands. Electronic address: dpfransz@gmail.com.
authors.forename: Duncan P
authors.initials: DP
authors.lastname: Fransz
authors.affiliation: MOVE Research Institute Amsterdam, Faculty of Human Movement Sciences, VU University Amsterdam, Amsterdam, The Netherlands; Department of Nuclear Medicine, Academic Medical Center, Amsterdam, The Netherlands.
authors.forename: Arnold
authors.initials: A
authors.lastname: Huurnink
authors.affiliation: adidas miCoach Performance Centre, AFC Ajax, Amsterdam, The Netherlands.
authors.forename: Vosse A
authors.initials: VA
authors.lastname: de Boode
authors.affiliation: MOVE Research Institute Amsterdam, Faculty of Human Movement Sciences, VU University Amsterdam, Amsterdam, The Netherlands.
authors.forename: Idsart
authors.initials: I
authors.lastname: Kingma
authors.affiliation: MOVE Research Institute Amsterdam, Faculty of Human Movement Sciences, VU University Amsterdam, Amsterdam, The Netherlands.
authors.forename: Jaap H
authors.initials: JH
authors.lastname: van Dieën
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D007866:Leg / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D009068:Movement / Q000502:physiology*; D004856:Postural Balance / Q000502:physiology*; D013997:Time Factors
keywords: Dynamic test; Force plate; Force platform; Ground reaction forces; Postural control