100 Dance Anatomy and Kinesiology
behavior of the epiphyseal plate. The pronounced
kyphosis (Dowager’s hump) seen with aging (and
particularly in postmenopausal women) involves ero-
sion and collapse of the anterior portion of one or
more thoracic vertebrae due to osteoporosis. These
and other medical conditions produce a structural
versus functional kyphosis that requires specific
medical treatment.
Kyphosis is often seen in association with other
spinal or pelvic deviations. When combined with
lumbar lordosis, the resultant postural deviation
is termed kypholordosis. When combined with a
forward displacement of the pelvis, the resultant
condition is termed fatigue posture.Fatigue Posture
Fatigue posture involves a forward displacement
of the pelvis relative to the ankle and “plumb line”
(Tests and Measurements 3.1) and backward dis-
placement of the torso relative to the pelvis and
“plumb line” as seen in figure 3.27A. The posterior
torso is frequently kyphotic, and the lumbar curve
varies according to the level and degree of posterior
displacement of the torso. In contrast to lumbar
lordosis posture, fatigue posture classically involves
hip joint extension or hyperextension rather than
flexion, and generally a posterior rather than ante-
rior tilt of the pelvis. This posture gets its name of
fatigue posture from the fact that it involves resting
on the ligaments (especially the iliofemoral ligament
discussed in chapter 4) for support and thus requires
almost no muscular effort for maintenance. Hence,
it actually requires less energy to stand with fatigue
posture than with ideal posture.
However, sustained use of ligaments for support
can be detrimental, while the associated posterior
shift of the weight of the trunk alters force transmis-
sion in the low back area such that sacroiliac pain may
occur. The posterior position of the torso also distorts
the normal transfer of weight of the arms and head
to the spine and can be associated with upper back
and neck fatigue or pain, and a compensatory forward
position of the head. The fatigue posture occurs very
frequently in mature individuals and in highly trained
dancers. For example, in a study of university dance
students and another study of adult non-dancers,
the average hip marker was found to be anterior to
the knee in standing posture (Woodhull, Maltrud,
and Mello, 1985; Woodhull-McNeal et al., 1990).
Similarly, in a study of young ballet dancers, about
half of Level 6 and almost all of the advanced/profes-
sional dancers studied displayed fatigue posture with
relaxed standing (Clippinger-Robertson, 1991).This high incidence of fatigue posture in dancers
may relate in part to the tendency for many danc-
ers to dramatically increase flexibility in the hip
flexors and other soft tissues to allow sufficient hip
hyperextension to achieve the desired aesthetic in
movements to the back such as arabesques. Since
with normal alignment the gravity line falls slightly
posterior to the axis of the hip joint, gravity would
tend to produce hip hyperextension. However, in the
dancer with increased range in this area, the normal
passive constraints that would limit this motion would
not be operative until much later, allowing excessive
posterior tilting of the pelvis and hip hyperextension
(e.g., the fatigue posture) unless (a) the iliopsoas is
actively used to prevent this, (b) the center of mass
of the torso is moved slightly forward to lessen this
extension tendency (extension moment), or (c) both
forms of correction are used. Another possible expla-
nation is that the lumbar flexion and posterior tilt ofFIGURE 3.27 (A) Fatigue posture; (B) activation of
thoracic spinal extensors and hip flexors.