Analysis of Human Movement 487aesthetically in many dance forms, can interfere with
allowing the normal slight posterior tilting of the
pelvis that accompanies higher ranges of hip flex-
ion and hence limit the height of the leg, interfere
with establishing relationships of the center of mass
of body segments desired for complex balancing,
produce increased shear forces in the low lumbar
spine, create an undesired increase in spinal exten-
sor activity, and negatively affect the biomechanics
of distal weight-bearing joints. Hence, correction of
this error can have significant impact on both dance
performance and injury risk. However, as previously
stated, this aspect of anatomical analysis requires
a keen understanding of the desired movement
characteristics, as well as a skillful analysis of the
causes of technique problems when they are present.
For example, is the lumbar lordosis just described
related to hip flexor tightness, low back tightness,
abdominal weakness, or suboptimal muscle activa-
tion patterns?
Other Methods for Movement Analysis
Despite the potential value, it is also important to
realize that a basic anatomical movement analysis
represents a gross simplification of what is actually
going on, used for practical purposes. Anatomical
analysis relies on determination of joint movement
(direction) through observation combined with
theoretical actions of key muscles to predict the
muscles that are primarily responsible for a given
movement. Hence, one can enhance its accuracy,
precision, and depth by referring to studies that
utilize quantitative analysis to substantiate or reject
theoretical predictions and by applying some basic
principles of mechanics.
Quantitative Versus Qualitative Analysis
The anatomical movement analysis presented in
this chapter utilizes a qualitative method of analysis.
Qualitative analysis involves a direct, subjective, non-
numerical evaluation by the senses, most commonly
a visual analysis. In contrast, quantitative analysis
involves objective numerical measurements of the
whole human body or its parts. These measure-
ments are generally not direct but rather are taken
from recordings of the movement performance.
Quantitative analysis can involve measurements
that relate to describing motion without reference
to the forces that produce the motion, termed kine-
matic data, or relate to the forces associated with
movement, termed kinetic data. Many tools can be
utilized to measure kinematic quantities, includ-
ing timing devices, computer-linked film analysis
(computerized cinematography), computer-linked
video analysis (computerized videography), devices
that are attached to joints to provide joint angle
recordings during movement (electrogoniometry),
and use of very small electric lights (light-emitting
diodes, or LEDs) or electromagnetic markers inter-
faced with cameras and computers (optoelectronic
systems).
Examples of information obtained from kine-
matic quantitative analysis include the displacement
of the center of gravity or landmarks of concern,
joint angles at different phases of movement, and
the rate or duration of motion of body segments.
Figure 8.9 shows the use of body landmark markers
and the application of a special type of goniometer
(electrogoniometer, or elgon) that is hooked up to
a recorder so that it can monitor changes in joint
angle during the movement being studied.
Tools for obtaining kinetic data include devices
used to measure applied forces for strength analysis
(dynamometers and tensiometers), pressure plat-
forms in shoes, or devices that can be attached to
a foot to provide graphical or digital informationFIGURE 8.9 Use of body landmark markers and an elgon to
study the plié.