Normal Human Locomotion, Part 2: Motion, Ground‐Reaction Force and Muscle Activity

In the patient care arena, an understanding of normal locomotion is a prerequisite to knowledge of pathological function in gait. Familiarity with joint motion, ground-reaction forces and muscular activity in normal individuals provides a bedrock of supporting knowledge that serves as a foundation for prosthetists and orthotists who seek to improve the performance of patients with pathological gait deficits. Although awareness of each of these components as it relates to a specific patient offers a revealing perspective by itself, in tandem they enable a three-dimensional differentiation between pathological and compensatory gait patterns. The sum is of far greater value than the individual parts. In the past, successful orthotic and prosthetic intervention was limited primarily by design and material characteristics. A relatively gross understanding of gait mechanics was sufficient. With advancements in materials science and componentry development, such as the miniaturization of external power sources, the limitations to a patient's performance using a prosthesis or orthosis is more likely than ever to hinge on the practitioner's knowledge of gait mechanics. This article, the second in a two-part series on normal human locomotion, attempts a narrative description of the dynamic phasic qualities of joint motion, ground-reaction forces and muscular activity.