Biomedical Engineering Reference
In-Depth Information
Figure 1.2 Flow of data from a camera system and plotting of data in two different
forms, each yielding a different description of the same event.
is represented by a straight line or stick. Joining the sticks together gives
the spatial orientation of all segments at any point in time. Repetition of this
plot at equal intervals of time gives a pictorial and anatomical description of
the dynamics of the movement. Here, trajectories, velocities, and accelera-
tions can by visualized. To get some idea of the volume of the data present
in a stick diagram, the student should note that one full page of coordinate
data is required to make the complete plot for the description of the event.
The coordinate data can be used directly for any desired analysis: reaction
forces, muscle moments, energy changes, efficiency, and so on. Conversely,
an assessment can occasionally be made directly from the description. A
trained observer, for example, can scan a stick diagram and extract useful
information that will give some directions for training or therapy, or give the
researcher some insight into basic mechanisms of movement.
The term monitor needs to be introduced in conjunction with the term
describe . To monitor means to note changes over time. Thus, a physical ther-
apist will monitor the progress (or the lack of it) for each physically disabled
person undergoing therapy. Only through accurate and reliable measurements
will the therapist be able to monitor any improvement and thereby make infer-
ences to the validity of the current therapy. What monitoring does not tell
us is why an improvement is or is not taking place; it merely documents
the change. All too many coaches or therapists document the changes with
the inferred assumption that their intervention has been the cause. However,
the scientific rationale behind such inferences is missing. Unless a detailed
analysis is done, we cannot document the detailed motor-level changes that
will reflect the results of therapy or training.
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