Introduction to Sports Biomechanics: Analysing Human Movement ...

although there are many exceptions to this. At the elbow, the triceps brachii is
antagonistic to brachialis and biceps brachii.
Stabilisers contract statically to fix one bone against the pull of the agonists so that
the bone at the other end can move effectively. Muscles that contract statically to
prevent movements caused by gravity are sometimes called supporting muscles, such
as the abdominal muscles in push-ups.
Neutralisers prevent undesired actions of the agonists when the agonists have more
than one function. They may do this by acting in pairs, as mutual neutralisers, when
they enhance the required action and cancel the undesired ones. For example, the
flexor carpi radialis flexes and abducts the wrist while the flexor carpi ulnaris flexes
and adducts the wrist: acting together they produce only flexion. Such muscles are
also sometimes called helping synergists. Neutralisers may also contract statically to
prevent an undesired action of agonists that cross more than one joint (multi-joint
muscles). The flexion of the fingers while the wrist remains in its neutral anatomical
position involves static contraction of the wrist extensors to prevent the finger
flexors from flexing the wrist. Such muscles are also sometimes called true synergists.
BOX 6.3 A SCHEMATIC MODEL OF SKELETAL MUSCLE
A simple schematic model of skeletal muscle is often used to represent its functionally different
parts. The model used is normally similar to Figure 6.10, and has contractile, series elastic, and
parallel elastic elements. The contractile component is made up of the myofibril protein filaments
of actin and myosin and their associated coupling mechanism.
Figure 6.10 Simple schematic model of skeletal muscle.
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