Muscles Acting as Force Couples
Force couples are muscles located in different positions relative to the axis of a joint but that act together to produce rotation or joint movement in the same direction. One that is particularly important in Pilate mat work is the abdominal-hamstringtorce couple (figure 3.5).because of the lower attachment of the abdomimals onto the pelvis, contraction of the abdominals can produce a posterior pelvic tilt Similarly, the attachments of the hamstrings onto the bottom of the back of the pelvis allow them to create a posterior pelvic tilt.
So even though these muscles are located on opposite sides of the pelvis, together they act to create the same movement: a posterior rotation of the pelvis. Sometimes in mat work, such as Pelvic Curl (page52), this action is used to create a posterior pelvic tilt. But in many other exercises this force couple is used to prevent an undesired anterior pelvic tilt (figure 3.5a)and maintain a neutral pelvis (figure 3.56). Different cues can encourage use of this force couple, such as "Focus on pulling the lower attachment of the abdominals upward as the hamstrings pull downward."
Figure 3.5. Abdominal-hamstring force couple. (a) Abdominals and hamstrings are relaxed. and
the force couple is inoperative. (b) The force couple acts to rotate the pelvis posteriorly to the
desired neutral position.
1. Start position. Lie supine with the knees bent and the feet flat on the mat
and hip-width apart. Place the arms by the sides with the palms facing down.
Focus inward, and consciously relax the neck, shoulders, and lower back
muscles while maintaining a neutral pelvic position.
2. Exhale. Draw the abdominal wall inward, and slowly curl the pelvis and lower,
middle, and upper back sequentially off the mat.
3. Inhale. Lift the upper trunk slightly higher to form a straight line on the side of
the body running through the shoulder, pelvis, and knee as shown in the main muscle illustration.
4. Exhale. Slowly lower the trunk, articulating each vertebra, to return to the start position. Repeat the sequence 10 times.
Spinal flexors: rectus abdominis, external oblique, internal oblique
Anterior spinal stabilizer: transversus abdominis
Pelvicfloor muscles. coccygeus, levator mi (pubococcygeus, pub~rect~ilsi,o qgeus)
Hip extensors: gluteus maximus, hamstrings (semitendinosus, semimembranosus,
Spinal extensors: erector spinae
Knee Mensors: quadricep9 femoris
Shoulder extensors: latissimus dorsi, teres malor, posterior deltoid