Analysis of Human Movement 483adduction with proximal segment—pelvis—moving)
to help return the trunk to vertical in the initial part
of the return phase (subphase C to D). The right hip
abductors, knee extensors, and ankle-foot plantar
flexors continue to act isometrically to maintain the
desired positioning of the gesture leg. Then, in the
later portion of the return phase (subphase D to E),
generally the hip abductors of the gesture leg briefly
work eccentrically to control the lowering of the leg
until the toe contacts the floor, at which point the
hip adductors work concentrically to draw the leg
back to the starting position while the knee exten-
sors continue to work isometrically to maintain the
knee in extension. After the toe contacts the ground,
concentric contraction of the ankle-foot dorsiflexors
and the passive effect of shifting the body weight back
over the right leg also act to produce the desired
dorsiflexion of the right ankle.
Looking at the upper extremity and simplifying
the analysis to the shoulders, the shoulder abduc-
tors work concentrically to simultaneously abduct
the right and left shoulder on the tilt phase of the
movement. On the return phase, gravity would tendMovement phases Joint movements
Contraction
type Prime movers: muscle group (sample muscles)Down-phase
Subphase: C to D
Right hip Hip extension
(Hip external rotation maintained)
Eccentric
IsometricHip flexors (iliopsoas, rectus femoris)
Hip external rotators (deep outward rotators)Right knee (Knee extension maintained) Isometric Knee extensors (quadriceps femoris)
Right ankle-foot (A-F plantar flexion maintained) Isometric A-F plantar flexors (gastrocnemius, soleus)
Right shoulder Shoulder extension Eccentric Shoulder flexors (anterior deltoid, pectoralis major)
Left shoulder Shoulder extension Eccentric Shoulder flexors (anterior deltoid, pectoralis major)
Subphase: D to E
Right hip Hip extension
(Hip external rotation maintained)
Concentric
IsometricHip extensors (hamstrings, gluteus maximus)
Hip external rotators (deep outward rotators)Right knee (Knee extension maintained) Isometric Knee extensors (quadriceps femoris)
Right ankle-foot A-F dorsiflexion Concentric A-F dorsiflexors (extensor digitorum longus, tibialis
anterior)
Left hip Hip flexion
(Hip external rotation maintained)
Eccentric
IsometricHip extensors (hamstrings, gluteus maximus)
Hip external rotators (deep outward rotators)Left knee Knee flexion Eccentric Knee extensors (quadriceps femoris)
Left ankle-foot A-F dorsiflexion Eccentric A-F plantar flexors (gastrocnemius, soleus)
Right shoulder Shoulder extension Eccentric Shoulder flexors (anterior deltoid, pectoralis major)
Left shoulder Shoulder extension Eccentric Shoulder flexors (anterior deltoid, pectoralis major)
Lateral Tilt
With the lateral tilt (table 8.5), the hip abductors
work concentrically on the gesture leg (right leg) to
raise the leg (hip abduction with distal segment—
femur—moving) in the beginning of the tilt phase
(subphase A to B), while the knee extensors work
isometrically to keep the knee extended and the
ankle-foot plantar flexors work concentrically to
point the foot. Then, as the torso tilts “up and over”
the support leg (subphase B to C), the hip adductors
work eccentrically on the support leg (left leg) to help
control the lateral tilt of the trunk via the pelvis (hip
abduction with proximal segment—pelvis—moving).
Once the torso is no longer vertically aligned relative
to the support leg, gravity would tend to make the
trunk rapidly fall to the left, and it is the eccentric
contraction of the hip adductors of the support leg
(and the isometric contraction of the right lateral
flexors of the spine) that are vital for controlling
this off-center movement and achieving the desired
dance aesthetic.
Now, to reverse the movement, the hip adductors
of the support leg now work concentrically (hip