A bundle of
Also called a
Middle of a
TYPES OF CONTRACTION
Isotonic contractions involve a change in muscle length,
as in the act of ﬂexing or extending your elbow (see
below) or transitioning in or out of an asana. Isometric
contractions involve tension with no change in muscle
length, such as when holding an asana.
Eccentric contractions occur when muscle ﬁbers
“lengthen” to change the angle of a joint. This
occurs in your biceps when extending your elbow
as you lower a weight, or in your hamstrings when
extending your knee as you transition from
Warrior II to Triangle (see pp.118–21) pose.
Skeletal muscles are bundles of bundles of bundles
of parallel muscle cells, blood vessels, and nerves
wrapped with connective tissue, including fascia.
Fascia creates a network through and around muscles
and other structures of your body. Microscopic
proteins in your muscles cause muscle contractions.
HOW MUSCLES WORK
Muscles often work in antagonistic pairs. As the
agonist muscle engages, the antagonist generally
releases. Synergist muscles engage around the joint
to support the action.
Edge of a
Made of the
Made of the
Fascia is similar to the white
pith of an orange; it separates
parts yet integrates the whole.
Fascia is not just found
around muscles. It is also
around vital organs and
woven throughout your body.
This body-wide network of
fascia is part of the reason
why a yoga pose that aects
your foot can suddenly
release your tight shoulders.
Flat band of
Angle of joint increases
Biceps brachii is the
antagonist as it
Triceps brachii is the agonist
as it concentrically contracts
to extend the elbow
US_020-021_Muscular_02.indd 20 04/12/2018 12:00