Time series graphs of single kinematic variables are conventionally used to assess movement patterns of both individual subjects and of different population groups. Phase plane plots that incorporate two spatial kinematic variables (joint angular position vs. joint angular velocity) have also been used to describe individual joint kinematics (Clarke, Truly & Phillips, 1990). Interjoint coordination of two sequential joints in a linked model can be assessed using graphing techniques including angle-angle plots (Grieve, 1969) and the relative phase angle between joints (Burgess-Limerick, Abernethy & Neal, 1993). The aims of this study were to assess the effect of age on both the individual hip and knee joint kinematics, and on hip-knee joint coordination throughout the swing phase of gait.

Ten young (24.0 ± 0.8 years (SEM)) and 8 elderly (69.2 ± 0.4 years (SEM)) healthy male subjects performed 5 walking trials at their normal gait velocity along a 14 m indoor walkway. 2D sagittal plane marker coordinates (50 Hz) of a subject’s right side were captured on video and digitised using a Peak Motus Motion Analysis system (Version 4.3). Relative joint kinematics were calculated from the raw marker coordinates, and were temporally normalised to a percentage of the swing phase. Graphs of hip and knee joint angular position and velocity, and phase plane plots were generated to identify differences in individual joint kinematics between the young and elderly subjects. Interjoint coordination was assessed through comparison of angle-angle (hip-knee) plots and the relative phase angle between the hip and knee joints (hip joint phase angle minus knee joint phase angle.

A qualitative comparison of the individual joint kinematics throughout the swing phase revealed no marked differences in joint kinematics from either the angular position vs. swing phase graphs or in the phase diagrams for the hip or the knee. A comparison of the angle-angle (hip-knee), and relative phase graphs for the young and elderly subjects did not reveal any marked differences in hip-knee joint coordination between the young and elderly subjects. From the results of this study it appears that both the individual kinematic patterns at the hip and knee joints, and hip-knee joint coordination during the swing phase of walking is not affected by age.