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After completing this chapter, you will
be able to:
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- Provide examples of linear, angular, and general forms
of motion.
- Identify and describe the reference positions, planes, and
axes associated with the human body.
- Define and appropriately use directional terms and joint movement
terminology.
- Explain how to plan and conduct an effective qualitative human
movement analysis.
- Identify and describe the uses of available instrumentation
for measuring kinematic quantities.
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Is it best to observe walking gait from a side
view, front view, or back view? From what distance can a coach best
observe a pitcher’s throwing style? What are the advantages
and disadvantages of analyzing a movement captured on video? To
the untrained observer, there may be no differences in the forms
displayed by an elite hurdler and a novice hurdler or in the functioning
of a normal knee and an injured, partially rehabilitated knee. What
skills are necessary and what procedures are used for effective
analysis of human movement kinematics?
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One of the most important steps in learning a new subject is
mastering the associated terminology. Likewise, learning a general
analysis protocol that can be adapted to specific questions or problems
within a field of study is invaluable. In this chapter, human movement
terminology is introduced, and the problem-solving approach is adapted
to provide a template for qualitative solving of human movement
analysis problems.
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Most human movement is general motion,
a complex combination of linear and angular motion components. Since linear
and angular motion are “pure” forms of motion,
it is sometimes useful to break complex movements down into their
linear and angular components when performing an analysis.
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Pure linear motion involves uniform motion of the system of interest,
with all system parts moving in the same direction at the same speed.
Linear motion is also referred to as translatory motion, or translation. When a body experiences
translation, it moves as a unit, and portions of the body do not
move relative to each other. For example, a sleeping passenger on
a smooth airplane flight is being translated through the air. If
the passenger awakens and reaches for a magazine, however, pure translation
is no longer occurring because the position of the arm relative
to the body has changed.
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Linear motion may also be thought of as motion along a line.
If the line is straight, the motion is rectilinear;
if the line is curved, the motion is curvilinear.
A motorcyclist maintaining a motionless posture as the bike moves
along a straight path is moving rectilinearly. If the motorcyclist
jumps the bike and the frame of the bike does not rotate, both rider
and bike (with the exception of the spinning wheels) are moving
curvilinearly while airborne. Likewise, a Nordic skier coasting
in a locked static position down a short hill is in rectilinear
motion. If the skier jumps over ...