Dance Anatomy & Kinesiology

330 Dance Anatomy and Kinesiology

While weight is distributed in a manner to avoid

excessive stress to any one structure with standing,

in movement the use of dorsiflexion, plantar flexion,

pronation, and supination alter foot characteristics

and stability.

Weight Distribution

on the Foot During Standing

During ideal standing, approximately 50% of the

body weight should be borne by the heel and the

remaining 50% transmitted across the metatarsal

heads (Sammarco, 1980). When weight bearing, the

anterior transverse metatarsal arch tends to flatten

so that all five metatarsal heads come in contact with

the ground. However, the load is not generally borne

evenly by these metatarsals. Instead, the load on the

metatarsal head of the great toe should be about

twice that of each of the metatarsal heads of the lesser

toes (figure 6.33). This is a helpful guideline to keep

in mind, as many dancers stand with excessive weight

on their heels or on the medial or lateral metatarsal

heads. Wearing high heels can also alter this weight

distribution and tends to increase loads borne by the

metatarsal heads associated with the lesser toes while

decreasing the load borne by the metatarsal head of

the hallux (Rasch, 1989).

Influence of Ankle Dorsiflexion

and Plantar Flexion on Stability

The integrity offered by the mortise architecture of

the ankle is not uniform in all positions. Although

there are large individual variations in shape, the

talus is generally slightly wedge-shaped with the

anterior articulating surface being broader than the

posterior (figure 6.34A). This structure produces a

snug and stable fit when the ankle is in dorsiflexion

or a neutral position with the foot at a 90° angle

to the tibia, such as when standing (figures 6.34, B

and D). However, when the ankle goes into plantar

flexion, such as when wearing shoes with high heels,

raising up on the toes, or jumping, the narrower por-

FIGURE 6.33 Ideal weight distribution on the foot

during standing (right foot, inferior view).

FIGURE 6.34 Change in ankle stability with position.

(A) Talus with wider anterior articular surface, (B) talus

sitting in mortise formed by malleoli and reinforced by

ligaments, (C) decreased stability in plantar flexion with

narrower portion of talus in mortise, (D) increased stabil-

ity in dorsiflexion with wider portion of talus in mortise.