The Knee and Patellofemoral Joints 281of open and closed kinematic chain strengthening
exercises in supplemental conditioning programs for
dancers (Clippinger, 2002). In terms of rehabilita-
tion, medical professionals will select appropriate
exercises in accordance with the specific injury and
relative advantages and disadvantages of these two
types of exercises.
Selected Stretches for the Knee
Table 5.4 provides the normal range of motion for
general populations (non-dance) as well as the struc-
tures that primarily limit further ranges of motion
for knee flexion and extension. And sample stretches
to improve range in these movements are described
shortly and shown in table 5.5.
In addition, adequate flexibility of some of the
multijoint muscles that cross the knee is important
for optimal knee mechanics. For example, tightness
in the iliotibial band can exert lateral forces on the
patella and increase knee injury risk (Jenkinson and
Bolin, 2001; Reid et al., 1987). Similarly, adequate
flexibility in the hip adductors is important for cor-
rect placement of the knees over the feet in posi-
tions such as turned-out second (Clippinger, 2005).
Distally, tightness of the calf muscles limits the depth
of the plié and can contribute to compensatory foot
pronation and resultant suboptimal knee mechan-
ics. Stretches for the hip abductors and adductors
were described in chapter 4, and calf stretches are
described in chapter 6.
Knee Extensor (Quadriceps) Stretches
Despite having markedly increased flexibility in many
other areas, dancers are frequently low in flexibility
in the knee extensors or quadriceps femoris muscle
group. This tendency for tightness appears to be more
prevalent (at least in ballet dancers) in dancers with
many years of training and almost universal in male
ballet dancers; 75% of female and 100% of male elite
ballet dancers tested exhibited quadriceps tightness
(Clippinger-Robertson, 1991). Another study of pre-
professional ballet dancers showed that 95% of these
dancers had at least minimal tightness of the rectus
femoris (Molnar and Esterson, 1997). A quick screen-
ing test is shown in Tests and Measurements 5.4 that
can be easily used to check quadriceps flexibility.
Stretches for this muscle group are often neglected
in the dancer’s regular stretching routine. Tight
quadriceps muscles may increase the risk for patel-
lofemoral problems, so it is important that adequate
flexibility be achieved and maintained.
To effectively stretch the vasti components of the
quadriceps, the knee must be brought into full flex-
ion, and the position of the pelvis is irrelevant since
these muscles do not cross the hip. In contrast, due
to the proximal attachment of the rectus femoris on
the anterior pelvis, care must be taken that the pelvis
is in a neutral or tucked position, since an anterior
pelvic tilt will slacken the rectus femoris and decrease
stretch effectiveness. Because the rectus femoris is
a hip flexor, bringing the hip into hyperextension
prior to bringing the knee toward the buttocks will
also increase the stretch to the rectus femoris.
The quadriceps are commonly stretched by using
the hand to bring the heel toward the buttocks while
standing, sitting on a chair (chair quadriceps stretch,
table 5.5B), lying on one side, or lying prone (heel-to-
buttocks stretch, table 5.5A). For whichever variation
is being used, it is important to realize that due to
knee joint structure, when the knee fully flexes the
distal tibia should angle medially relative to the shaft
of the femur. Hence, this normal motion should be
allowed and twisting of the tibia should be avoided.
The chair quadriceps stretch (table 5.5B) allows the
quadriceps to be stretched in a position in which the
torso is vertical and maintaining a neutral pelvis can
be more readily achieved. The low lunge quadriceps
stretch provides a challenging position for the more
flexible dancer with adequate hip flexor flexibility
in that the weight is on the thigh and above theTABLE 5.4 Normal Range of Motion and Constraints for Primary Movements of the Knee
Knee joint movement Normal range of motion* Normal passive limiting factors
Flexion 0-135° Soft tissue apposition: posterior aspects of thigh and calf or
heel and buttocks
Muscles: quadriceps femoris
Extension 0-10° Capsule: posterior portion
Ligaments: cruciates, medial collateral, lateral collateral, and
oblique posterior (a ligament located posteriorly)
Muscles: hamstrings (when hip in marked flexion)*From American Academy of Orthopaedic Surgeons (1965).