Dance Anatomy & Kinesiology

262 Dance Anatomy and Kinesiology

closer together. The hamstrings and other flexors

of the knee (table 5.2) are used concentrically when

flexion is occurring against gravity or resistance as

in prone knee curls (table 5.3E, p. 276) or standing

knee curls (table 5.3F, p. 277). The knee flexors are

also used concentrically to flex the knee as the lower

limb swings backward during walking and running

gait. In dance, the knee flexors can also be used to

shorten the length of the limb to facilitate turning,

as in fouetté turns, and to effect a desired shape such

as in a passé, attitude, or the back leg of the stylized

stag leap seen in figure 5.19.

However, during standing with the weight of the

body supported by the foot, the situation is differ-

ent. Once the knee is “unlocked” and begins to

flex, gravity becomes the primary force and tends

to create further flexion of the knee. Under these

circumstances the knee flexors are not working to

create knee flexion; rather the knee extensors are

working to either maintain that angle of knee flex-

ion (isometrically) as seen in figure 5.20 or control

further flexion (eccentrically) as when the body is

being lowered to the floor. So, the knee extensors

(quadriceps femoris) act in this postural or “antigrav-

ity” role very frequently in dance on the support leg

or legs. In impact movements such as jumping, this

eccentric knee flexion is vital for shock absorption

and deceleration of the falling body.

FIGURE 5.18 Increasing patellofemoral compression force. (A) Knee almost straight, (B) greater knee flexion, (C)

greater magnitude of quadriceps contraction.

TABLE 5.2 Knee Movements and the Muscles That Can Produce Them

Knee joint movement Primary muscles Secondary muscles

Flexion Hamstrings Popliteus*

Gracilis

Sartorius

Gastrocnemius

Extension Quadriceps femoris Tensor fasciae latae

External rotation Biceps femoris Tensor fasciae latae

Internal rotation Semitendinosus

Semimembranosus

Popliteus (when foot free)

Gracilis

Sartorius

*Unlocks the knee at beginning of knee flexion.