Page 148 - Biomedical Engineering and Design Handbook Volume 1, Fundamentals

CHAPTER 6

BIOMECHANICS OF HUMAN

MOVEMENT

Kurt T. Manal
University of Delaware, Newark, Delaware

Thomas S. Buchanan
University of Delaware, Newark, Delaware

6.1 WHY STUDY HUMAN MOVEMENT? 125 6.4 ANALYSIS OF HUMAN MOTION:
6.2 FORWARD VERSUS INVERSE AN INVERSE DYNAMICS APPROACH 136
DYNAMICS 126 6.5 CONCLUDING REMARKS 150
6.3 TOOLS FOR MEASURING HUMAN REFERENCES 151
MOVEMENT 129

6.1 WHY STUDY HUMAN MOVEMENT?

The biomechanics of human motion is a fascinating field. Who among us has never marveled at the
graceful motions of a dancer, or the rapid finger movements of a musician? From the time of
Aristotle onward there have been countless books written on the topic of movement in animals and
humans. Despite the great minds that have considered the topic, it is just recently that much advance-
ment has been made experimentally. Historically, the study of human movement has been costly and
very time consuming. This is because in order to study them, movements are almost always
discretized and then analyzed step-by-step, with the size of the steps determined by the speed of the
movement (and the questions being asked). Whether it be frames of film from a video camera or
digitized samples from an electrogoniometer, most movements are recorded as series of static images
which are then reassembled to provide kinematic and kinetic information.
There has been a tremendous growth in the study of human movement in the past two decades
due to the low cost of digital data acquisition systems that make possible the storage and analysis of
massive amounts of data that are required to accurately characterize complex motion. This growing
interest in the study of human movement is coming from five predominate groups.
First, basic scientists are interested in the control of human movement. How the nervous system
controls the large number of degrees of freedom necessary to produce smooth, complex movements
(or even simple ones!) is poorly understood. The study of the coordination of movement can be
compared to the inverse problem faced by the roboticist. The roboticist develops computer programs
to produce coordinated movements in a robot. On the other hand, the motor control researcher measures
coordinated movements in order to understand what the “neural program” is.
Second, human movements are studied to understand and treat pathologies. For example, gait
analysis is often used to help guide the physician contemplating surgery for children with cerebral
palsy. The best choice for a tendon transfer or muscle lengthening surgery can be predicted using

125