Je. Zachazewski et al., BIOMECHANICAL ANALYSIS OF BODY-MASS TRANSFER DURING STAIR ASCENT AND DESCENT OF HEALTHY-SUBJECTS, Journal of rehabilitation research and development, 30(4), 1993, pp. 412-422
The purposes of this study were to: 1) assess whole body center of mas
s (CM) motion in the frontal, sagittal, and transverse planes; 2) comp
are CM displacement with center of pressure (CP); and, 3) further defi
ne the stance and swing subphases of stair ascent (SA) and stair desce
nt (SD) based on critical CM, CP, and ground reaction force (GRF) even
ts. SA and SD were analyzed on a convenience sample of 11 subjects. Un
paced data were collected from 28 SA trials and 24 SD trials utilizing
a bilateral SELSPOT II(T)/TRACK(C) data acquisition system and two Ki
stler force plates at a sampling frequency of 153 Hz. Twenty-six discr
ete data points were chosen from each trial for analysis. Each identif
ied point detailed the intersection, separation, maximum or minimum va
lue of CM, CP, or GRF in all three planes. Specific phases of SA and S
D are presented and described. The actions of CM, CP, and GRF are pres
ented during each phase. Results further refine the phases originally
described by McFayden and Winter. Subtle differences in phases and dur
ation of single and double support are demonstrated between SA and SD.
Based on these results, it is apparent that SD is a more dynamic proc
ess with greater inherent instability. Knowledge of SA and SD phases a
nd CM/CP dynamics in healthy, normal subjects will permit comparison w
ith patients exhibiting various pathologies. Such comparison should fa
cilitate the development of appropriate intervention strategies.