1. The influence of stimulus cue on the initiation of stepping in young and older adults 
Mark W. Rogers, PhD, PT, Carl G. Kukulka, PhD, PT, Denis Brunt, EdD, PT, Thomas D. Cain, MD, Timothy A. Hanke, MS, PT 
Archives of Physical Medicine and Rehabilitation 
Volume 82, Issue 5, Pages (May 2001)
DOI: /apmr
Copyright © 2001 American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation Terms and Conditions

2. Fig. 1
Representative data from 1 subject showing the ground reaction force events used to quantify step initiation. The bottom record is the vertical (Fz) force beneath the first step limb. Also shown are the net COP recordings in the ML and AP directions. The dotted, vertical line marks the instant of the reaction stimulus onset. The solid, vertical lines from left to right mark the time of onset of the postural response (PR) as noted by the arrow on the Fz record, the onset of unloading (UL) at the time of peak Fz, and the time of lift-off (LO) when Fz is reduced to zero. The different timing phases (top) are determined from these events. %BOS indicates displacement of the COP as a percentage of the base of support (BOS) width and length.
Archives of Physical Medicine and Rehabilitation  , DOI: ( /apmr )
Copyright © 2001 American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation Terms and Conditions

3. Fig. 2
Group mean (± standard error of the mean [SEM]) COP magnitude data for young and elderly subjects as a function of the different reaction stimulus cues. In (A) the asterisk indicates a significant main effect of stimulus cue with cutaneous > light and sound; in (B), the asterisk indicates a significant main effect of group for all stimulus cues. ■, young; ▨, elderly.
Archives of Physical Medicine and Rehabilitation  , DOI: ( /apmr )
Copyright © 2001 American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation Terms and Conditions

4. Fig. 3
Individual mean data for young (n = 15) and elderly (n = 35) subjects showing the ML COP magnitude ratio values for the cutaneous (C) reaction stimulus relative to the light (L) and sound (S) stimuli. Ratio values (× 100 = %) are normalized to the C/C ratio = 100% as indicated by the horizontal dotted lines.
Archives of Physical Medicine and Rehabilitation  , DOI: ( /apmr )
Copyright © 2001 American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation Terms and Conditions