496 Dance Anatomy and Kinesiology
the desired position of the back leg (almost paral-
lel to the floor) in the flight phase. This can relate
to hip flexor tightness of the back leg, hamstring
tightness of the front leg, limited range in spinal
hyperextension, inadequate hip extensor strength of
the back leg, inadequate spinal extensor strength, or
inappropriate timing and activation of key muscles.
Another important technique consideration is skilled
use of flexion of the support leg (hip flexion, knee
flexion, and ankle dorsiflexion) during the prepara-
tion phase to provide a prestretch of the extensors
(hip extensors, knee extensors, and ankle plantar
flexors) that will markedly enhance the ability of the
muscle to generate force (stretch-shortening cycle)
in the takeoff phase. While some dancers appear to
display a natural use of this potential enhancement,
other dancers do not fully utilize this mechanism
due to errors such as making the preparatory move-
ment too large or too small and excessively delaying
the reversal from flexion to extension. One study
showed that 36% of young ballet dancers were not
able to use this elastic potential of muscle correctly
and were able to jump higher from a semi-squatting
position without a countermovement than when a
countermovement (preparatory plié) was used (Pog-
gini et al., 1997). However, another study of skilled
dancers showed a consistent submaximal depth of
demi-plié prior to various movements, suggesting
a preset motor program (Clarkson, Kennedy, andFlanagan, 1984; McNitt-Gray, Koff, and Hall, 1992)
that may relate to stretch-shortening optimization
and movement economy. Experienced dancers have
also been shown to utilize a faster reaction time in
the preparatory plié prior to a sauté than in other
movements requiring less power (relevé or pointe)
or than non-dance controls (Clarkson, Kennedy, and
Flanagan, 1984). Hence, encouraging dancers to
use a moderate depth of preparatory plié (Ryman,
1978) and to make a rapid reversal from flexion to
extension can help some dancers reap potential
stretch-shortening cycle benefits and enhance jump
height or distance.
Similarly, the timing and magnitude of flexion of
the support leg during the landing phase are also
important. In this case, the issue is primarily one
of absorption of forces versus generation of forces,
essential for injury prevention as well as achieving
dance aesthetic criteria. Increasing the time used to
decelerate the body when landing from a jump will
decrease the magnitude of the peak forces borne
by the body. An eccentric contraction of the exten-
sors of the hip, extensors of the knee, and plantar
flexors of the ankle to allow greater flexion at their
respective joints can be used to provide more time for
absorption of forces. So, soft landings are associated
with lower peak vertical ground reaction forces that
remain elevated for a longer period of time, while
hard landings are associated with higher peak verticalQuick Check for Limitations Due to Passive Hip Constraints
in a Grand Jeté en AvantPerform a passive split with
the torso vertical and com-
pare this position of the legs
to the position seen when
executing a grand jeté. If
a dancer cannot achieve
or has difficulty achieving
the passive split position,
this suggests that the ham-
strings or hip flexors are
likely limiting the desired
positioning of the legs in the
grand jeté.