Quantification of stability in an agility drill using linear and nonlinear measures of variability

Mehdizadeh, Sina, Arshi, Ahmed Reza, & Davids, Keith (2014) Quantification of stability in an agility drill using linear and nonlinear measures of variability. Acta of Bioengineering and Biomechanics, 16(3), pp. 59-67.

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Abstract

This study implemented linear and nonlinear methods of measuring variability to determine differences in stability of two groups of skilled (n = 10) and unskilled (n = 10) participants performing 3m forward/backward shuttle agility drill. We also determined whether stability measures differed between the forward and backward segments of the drill. Finally, we sought to investigate whether local dynamic stability, measured using largest finite-time Lyapunov exponents, changed from distal to proximal lower extremity segments. Three-dimensional coordinates of five lower extremity markers data were recorded. Results revealed that the Lyapunov exponents were lower (P < 0.05) for skilled participants at all joint markers indicative of higher levels of local dynamic stability. Additionally, stability of motion did not differ between forward and backward segments of the drill (P > 0.05), signifying that almost the same control strategy was used in forward and backward directions by all participants, regardless of skill level. Furthermore, local dynamic stability increased from distal to proximal joints (P < 0.05) indicating that stability of proximal segments are prioritized by the neuromuscular control system. Finally, skilled participants displayed greater foot placement standard deviation values (P < 0.05), indicative of adaptation to task constraints. The results of this study provide new methods for sport scientists, coaches to characterize stability in agility drill performance.

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ID Code: 88494
Item Type: Journal Article
Refereed: Yes
Keywords: foot placement variability, largest finite-time Lyapunov exponent, local dynamic stability, standard deviation
DOI: 10.5277/abb140307
ISSN: 1509-409X
Divisions: Current > QUT Faculties and Divisions > Faculty of Health
Current > Institutes > Institute of Health and Biomedical Innovation
Deposited On: 19 Oct 2015 03:56
Last Modified: 19 Oct 2015 04:00

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