Analysis of Human Movement 477In contrast, correcting the distal foot pronation
by contracting the foot inverters, without addressing
the underlying more fundamental alignment of the
spine and pelvis, will often not provide the desired
corrections proximally and may result in muscle
fatigue and potentially shin splints if positioning
of proximal segments are producing large internal
rotation forces of the tibia that are countered by only
relatively small muscles of the foot. It is also gener-
ally not possible to maintain this distal correction in
dynamic movement, which requires complex adjust-
ment of the joints of the feet including relative prona-
tion and supination to meet the demands of shock
absorption and propulsion in locomotor movements.
However, it is important to note that in athletes that
wear shoes (such as runners), distal correction with
well-designed arch supports or orthotics, rather than
superimposed contraction of the inverters, can often
be helpful for improving technique.
Special ConsiderationsIn faster movements, movement analysis can become
more complex. Rather than the more sustained use
of a prime mover with a certain type of contraction
throughout most or all of a phase, bursts of muscle
activity, the use of momentum, and quick changes
in contraction type play a more prominent role. For
example, as the thigh swings forward during low leg
swings, the hip flexors are briefly used concentrically
to initiate the motion; next, momentum becomes
primary; and then toward the end of the forward
motion, the hip extensors are used eccentrically to
decelerate the thigh and then concentrically to initi-
ate the swing of the leg in a backward direction in the
next phase of the movement. This eccentric use of
muscles to aid with changing the direction of move-
ment of a limb does not invalidate classic movement
analysis, which would suggest that the hip flexorsInfluence of Spinal-Pelvic Alignment
on Distal Joint MechanicsStand in a turned-out second position in front of a mirror.- Valgus and varus position of the knee. Perform a demi-plié in a second position, focusing on
guiding the middle of your kneecap over your second toe as your knees bend. Then, purposely slowly
anteriorly tilt the pelvis, letting the top of the pelvis rotate forward. Notice the associated tendency
for your knees to move inward, creating a valgus position of the knee. Now, purposely slowly posteri-
orly tilt the pelvis, bringing the bottom of the pelvis forward while the top of the pelvis rotates back.
Notice the associated tendency for your knees to move outward, perhaps even to a position where
they are behind the axis of the foot (varus position of the knee). Lastly, establish a neutral position
of the pelvis where the top of the anterior pelvis (anterior superior iliac spines) is vertically aligned
above the bottom of the anterior pelvis (pubic symphysis) and see if you can more readily position
the midpoint of your patellas over your second toes. - Foot pronation and supination. Again, perform a demi-plié in second position, focusing on guiding
the middle of your kneecap over your second toe, with the foot in neutral alignment. Then, purposely
slowly anteriorly tilt the pelvis, and notice that as the knees fall inward, the feet also tend to roll in,
creating a pronated position of the feet. Next, posteriorly tilt (tuck) the pelvis, and notice that as your
knees tend to move outward, the feet also tend to roll out, creating a supinated position of the foot.
Lastly, establish a neutral position of the pelvis, and see if you can position the mid-patella approxi-
mately over the second toe such that the foot is in a neutral position with slightly more weight placed
over the base of the big toe versus the little toe, and a formed longitudinal arch. - Changes in muscle use. Again, while maintaining a second-position plié, anteriorly tilt your pelvis,
and this time also let your torso slightly lean forward. Notice if you feel any difference in muscle use
with this misaligned position than when in a neutral position. Go back and forth between these posi-
tions several times to check your observation. Some dancers experience a greater sense of work in
the quadriceps femoris and tensor fasciae latae in the misaligned position and more ability to feel
the hamstrings working in the correctly aligned position.