Fundamentals of Biomechanics

parallel elastic component: a part of the
Hill muscle model that represents the
passive tension from connective tissue
throughout the muscletendon unit
Pascal: the SI unit of pressure or stress
(force per unit area)
passive insufficiency: the limitation of
joint motion because of increases in
passive tension in multiarticular muscles
stretched across multiple joints
passive tension: a component of muscle
tension from passive stretching of muscle,
especially the connective tissue
components
pennation: the angle of muscle fiber bundles
relative to a tendon
piezoelectric: crystals with electromechanical
properties that can be used to measure
force/acceleration
point mass: a simplified mechanical model
that represents an object as a point in
space with a given mass
potential energy: the capacity to do work
of an object due to its vertical position
in a gravitational field (gravitational
potential energy) or its deformation
(strain energy)
potentiometer: a device that is used to
measure rotation
power (mechanical): the rate of doing mechanical
work; peak mechanical power
represents the greatest mechanical effect,
the ideal combination of force and
velocity; power can be calculated as
W/t or F • V
preamplification: the amplification of
small signals (EMG) close to their
source before they are conducted to
other devices for amplification and
recording
pressure: external force divided by area
over which the force acts
APPENDIX A: GLOSSARY 291
projectile: an object projected into space
without self-propulsion capability, so
the only forces acting on the object are
gravity and air resistance
proprioceptive neuromuscular facilitation
(PNF): specialized stretching procedures
that utilize sequences of muscle
actions to potentiate reflexes to relax
muscles being stretched
prosthetics: artificial limbs
Pythagorean Theorem: the two sides of a
right triangle forming the right angle (a
and b) and the hypotenuse (c) are related
as follows: a2 + b2 = c2 qualitative analysis: systematic observation
and introspective judgment of the
quality of human movement for the
purpose of providing the most appropriate
intervention to improve performance
(Knudson & Morrison, 2002)
quantitative analysis: solving a biomechanical
problem using numerical
measurements and calculations
quasistatic: the state of a mechanical system
where the accelerations are small
enough to be assumed equal to zero
radian: a dimensionless unit of rotation
equal to 57.3°
radius of gyration: a convenient way to
summarize an object's moment of inertia,
defined as the distance from the axis
of rotation at which half the object's
mass must be placed in both directions
to equal the object's moment of inertia
range-of-motion principle: a biomechanical
application principle which states
that the amount of linear and angular
motion used will affect the speed and
accuracy of human movement