A Kinematic And Kinetic Analysis Of Two Stair-stepping Machines At Two Speeds

Abstract

The use of stairstepping machines has increased significantly in the areas of fitness and rehabilitation. The purpose of this study was to compare the kinematic and kinetic variables of two different machines, Stair-master 4000PT (SM) and Lifestep (LS), at 2 different speeds. Twenty-six female subjects (age: 20.4+1.7 yrs; height: 167.5 +5.9 cm; mass: 62.2+8.3 kg) volunteered for this study. Subjects we-re given a brief warm-up time and then stepped for 10 seconds at each condition: Stairmaster-level4 (SM4), Stairmaster-level 8 (SM8), Lifesteplevel 4 (LS4), and Ufestep-level8 (LS8). Each subject was videotaped from the sagittal view with a Panasonic AG-450 camcorder set at 1/500th shutter speed and 30 Hz frame rate. Reflective markers were placed at Slower body and trunk landmarks of the right side of each subject. Each subject's view was captured, data points digitized, transformed and spatial coordinates analyzed using the Ariel Performance Analysis System. Data were smoothed with a digital filter set at 10 Hz. ANOVA with randomized blocks design was utilized to examine differences in the kinematic and kinetic variables. A significant difference was found between LS4 and SM4 for the variables of: hip (HROM), knee (KROM), and ankle (AROM) range of motion, Y peak force of the hip (YHP), knee (YKN), and ankle (YAN) and X peak force of the knee (XKN) and ankle (XAN). Significant differences were found between LS8 and SM8 for the variables of HROM, KROM, YHP, YKN, XKN, and XAN. Greater ranges of motion and increased Y and X forces were found in the LS conditions. .Significant differences were also noted between different speeds. From a rehabilitative standpoint, it is important that the therapist understand the differences between machines when recommending a protocol on a stairstepping machine.