Dance Anatomy & Kinesiology

64 Dance Anatomy and Kinesiology

Electromyography

Examples of EMG records of three muscle groups for danc-

ers directed to stand in first position, “prepared,” as if they

were in class, is shown. Records from two professional ballet

dancers and two advanced modern dancers were selected to

show the range in response with the same position. With this

version of testing, the magnitude of the tracing of a muscle

during a given movement is compared to that of a maximum

voluntary contraction of the same muscle with the same

electrode application.

Key:

A = hip adductor (adductor longus)

Q = quadriceps femoris (vastus medialis)

H = hamstrings (biceps femoris)

FIRST POSITION–BALLET

TESTS AND MEASUREMENTS 2.1

movement set into play by gravity. For students new to

anatomy, this is a difficult concept to grasp. It is help-

ful to consider whether the movement of the body or

its segments is primarily (1) opposite to the direction

of gravity (upward) or (2) in the same direction as

gravitational forces (downward). For slow, controlled

movements, movements opposite to the direction of

gravity are generally produced by concentric muscle

contraction of muscles whose action is the same as

the direction of movement, while movements in the

same direction as gravity will be produced by gravity

and controlled by eccentric contraction of muscles

whose action is in the opposite direction to the joint

movement occurring.

For example, in a plié in first position (figure

2.21), the up-phase would be going against gravity,

and the knee extensors (quadriceps femoris) would

be working concentrically to produce knee exten-

TABLE 2.5 Simplified Movement Analysis of Demi-Plié in Parallel First Position

Phase

Hip joint

motion

Hip muscle

group

Type of

contraction

(sample

muscles)

Knee joint

motion

Knee

muscle

group

Type of

contraction

(sample

muscles)

Up-phase Hip

extension

Hip

extensors

Concentric

(gluteus

maximus,

hamstrings)

Knee

extension

Knee

extensors

Concentric

(quadriceps

femoris)

Down-phase Hip flexion Hip

extensors

Eccentric

(gluteus

maximus,

hamstrings)

Knee flexion Knee

extensors

Eccentric

(quadriceps

femoris)

Selected key joints: Hip, knee

S7

A

Q

H

S13

A

Q

H

FIRST POSITION–MODERN

S9

S3