A new force-plate technology measure of dynamic postural stability: the dynamic postural stability index.
BACKGROUND
New measures of dynamic postural stability are needed to address weaknesses of previous measures.


OBJECTIVE
To assess the feasibility, reliability, and precision of a new measure of dynamic postural stability.


METHODS
A single within-subjects design was used to determine optimal sampling interval as well as intersession reliability.


METHODS
Biomechanics laboratory.


METHODS
Eighteen subjects (7 men [age = 22 +/- 3 years, height = 175 +/- 5 cm, mass = 75 +/- 16 kg] and 11 women [age = 23 +/- 2 years, height = 163 +/- 6 cm, mass = 68 +/- 13 kg]) without lower extremity impairment.


METHODS
A jump protocol that required subjects to perform a 2-legged jump to a height equivalent to 50% of their maximum vertical leap and land on a single leg.


METHODS
The Dynamic Postural Stability Index (DPSI) and the directional components (medial-lateral, anterior-posterior, and vertical) after a jump landing.


RESULTS
We observed a significant sampling-interval main effect (F(2,51) = 26.88, P < .01) for the DPSI; the 10-second trial duration produced significantly smaller means than the 5- and 3-second trial durations, whereas the 5-second trial result was also significantly smaller than that of the 3-second trial. The DPSI was highly reliable between test sessions (intraclass correlation coefficient = .96) and very precise (SEM = .03).


CONCLUSIONS
These results suggest that the DPSI can be used in conjunction with a functional single-leg hop stabilization test and is a reliable and precise measure of dynamic postural stability. We believe the shortest sampling interval (3 seconds) is the best choice for studying and mimicking athletic performance as closely as possible.
Wikstrom
Erik A
EA
Department of Applied Physiology and Kinesiology, University of Florida, PO Box 118205, Gainesville, FL 32611-8205, USA. ewikstrom@hhp.ufl.edu
Tillman
Mark D
MD
Smith
Andrew N
AN
Borsa
Paul A
PA