Article

The purpose of this study was to analyze age-related movement smoothness changes
in the lower extremity joints during load lifting. A total of 10 young and 13
elderly subjects participated in the study. Infrared reflective markers were
attached to body landmarks in each subject. While the subjects stood on force
plates and lifted a box, the marker displacements and ground reaction forces were
measured using a 3D motion analysis system. The jerk square mean value (JSM) was
defined as the lower extremity joint movement smoothness index during lifting.
JSM represented the average of the square of the joint angle third derivative
value, according to the jerk third derivative of the position data. Each
subject's JSM values were calculated for the hip, knee and ankle joints. Movement
smoothness appeared to decrease as JSM increased. Multiple regression analyses
were performed for dependent variables (hip, knee and ankle joint JSM values) and
independent variables (age, hand grip strength, sex difference and lifting
duration). The level of significance was set at p<0.05. For the hip joint JSM,
the regression coefficient for age was significantly positive and that for
lifting duration was significantly negative. For the knee joint JSM, the
regression coefficient for lifting duration was significantly negative. For the
ankle joint JSM, the regression coefficients for age and hand grip strength were
significantly positive and that for lifting duration was significantly negative.
These results suggest that movement smoothness in the hip and ankle joints during
lifting decreases with advancing age.

Langue : ANGLAIS