Utilizing gaitline velocity in dynamic gait analysis

The dynamic loads that are transmitted to the body during heel strike have been topics of discussion in various literature. The magnitude of the excitation loads that are transmitted through the lower extremities to the spine and upper extremities depends on the dynamic characteristics of the body´s lower extremities. Since the greatest excitation forces are encountered during heel strike, it becomes important to define the amount of energy imparted to the body during the gait phase. The objective of this study was to examine gait-line velocities taken on various subjects to establish dynamic patterns during normal gait. Needham collected data on 10 subjects utilizing a Novell Pedobarographic EMED system. The subjects did not show any visible foot´s abnormalities during a podiatric examination. The data were taken while the subjects walked normally wearing four different types of shoes and once with only a sock. Each time data were measured and recorded using the pedobarographic inshoe-insole data acquisition system that had 99 sensors spaced across each planar foot. The data were further reduced to display the gait line velocity for the various subjects as a function of shoe types. The gait line is the average instantaneous force over the planar foot as a function of time. Gait-line velocities from Needham´s study were compared to similar data from a previous study where pronation and supination were artificially induced during the gaits. Results from the study indicate that there are definite dynamic patterns in the gait-line velocity. A negative velocity is notable at heel strike and is more pronounced without shoe support. Without shoe support the peak velocity is higher and occurs earlier that with shoe support. The peak velocity occurs near the middle of the stance phase. The velocity varies when foot abnormalities are present: greatest when there is pronotion and least when there is supination