Introduction to Sports Biomechanics: Analysing Human Movement ...

THE ANATOMY OF HUMAN MOVEMENT
Depolarisation A reduction in the potential of a membrane.
Differentiation Expresses the rate at which a variable changes with respect to the change
in another variable on which it has a functional relationship.
Dynamometry The measurement of force or torque output; used as an estimate of
muscular strength.
Elasticity The property of a material to return to its original size and shape. See also
plasticity and viscoelastic.
Electrical potential The voltage across a membrane at steady-state conditions.
Frequency domain An analysis technique whereby the power of the signal is plotted
as a function of the frequency of the signal. See also power spectrum and time
domain.
Impedance (electrical) The ratio of voltage to electric current; a measure of opposition
to time-varying electric current in an electric circuit. Sometimes identical to
resistance.
Isokinetic exercise An exercise in which concentric muscle contraction moves a limb
against a device that is speed controlled.
Isometric Muscle action in which tension develops but there is no visible or external
change in joint position; no external work is produced. See also isometric exercise.
Isometric exercise An exercise that loads the muscle in one joint position.
Isotonic Muscle contraction in which tension is developed either by the lengthening
(eccentric) or shortening (concentric) of muscle fibres. See also isotonic exercise.
Isotonic exercise An exercise in which an eccentric and or concentric muscle contraction
is generated to move a specified weight through a range of motion.
Lag The number of data points by which a time series is shifted when one is calculating
a cross-correlation with another time series or an autocorrelation with the same, but
lagged, time series.
Loose-packed position The joint position with less than maximal contact between
the articular surfaces and in which contact areas frequently change. See also closepacked
position.
Maximal voluntary contraction The maximal force that is exerted by a muscle during a
static contraction against an immovable resistance.
Motor end-plate A flattened expansion in the sarcolemma of a muscle that contains
receptors to receive expansions from the axonal terminals; also called the neuromuscular
junction.
Motor unit A motor neuron and all the muscle cells it stimulates.
Neuromuscular junction Region where the motor neuron comes into close contact with
(innervates) skeletal muscle; also called the motor end-plate.
Normal stress The load per cross-sectional area applied perpendicular to the plane of
cross-section of an object. See also shear stress.
Pelvic girdle The two hip bones plus sacrum, which can be rotated forwards, backwards
and laterally to optimise positioning of the hip joint.
Plasticity Refers to the condition of connective tissue (ligaments or tendons) that has
been stretched past its elastic limit and will no longer return to its original shape.
See also elasticity and viscoelastic.
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