INFLUENCE OF STAIR DIMENSIONS AND SUBJECT HEIGHT ON ANGULAR DISPLACEMENT OF THE TRUNK DURING STAIRCLIMBING

For more than a decade, stairclimbing has been touted (e.g., Edwards, 1983) as an easy and effective way to build physical activity into one's daily routine, for staircases are both readily available and they require the climber to move against a natural resistance force (i.e., gravity). Yet gravity may destabilize the climber and lead to a potentially injurious fall if the line of gravity (i.e., centre of mass)falls outside the climber’s base of support. It has been suggested that stabilitymay be accomplished by varying the orientation of the trunk segment (Krebs etal., 1992) yet systematic investigations of the relationship between trunk orientation, the internal constraints (e.g., subject height), and external constraints(e.g., stair dimensions) imposed when stairclimbing have yet to be reported. The purpose of this study, therefore, was to examine the angular displacement of the trunk while climbing over stairs of differing dimensions. Six healthy, physically active young-adult females with a mean age of 21.8 years (SD = 2.6), grouped by height, completed 10 trials each of free-speed stair ascent and descent over three staircases classified as steep (45º), moderate (33 º), or shallow (16 º) in slope. Results of a mixed between-within repeated measures MANOVA yielded several significant results. While ascending stairs, those subjects classified as short in height demonstrated significantly (F(2,9)=5.32, p