Pilates Anatomy

Chapter 4

Foundation for a Mat Session

This chapter focuses on exercises that can be performed at the beginning of the mat session. These exercises emphasize the powerhouse, discussed in chapter 2, and serve as a specific warm-up to help prepare you for the more challenging Pilates exercises that follow. They also provide an opportunity to shift your mental focus inward, let go of the stressors of everyday life, and develop an inner calmness.

Although they seem simple, do not miss the value of these foundation exercises. In accordance with the physiological principles of a warm-up, these exercises are less complex and less challenging in terms of balance than many exercises from the classic mat work that appear later. Also, these foundation exercises can be performed more slowly and the difficulty adjusted easily by beginning with a smaller range of motion and progressing to a larger range. Hence, these exercises provide a perfect opportunity to focus on more internal and detailed elements of exercise execution—elements that distinguish Pilates from many other exercise systems.

Technique elements covered in this chapter are activation of the pelvic floor muscles, activation of the transversus abdominis muscle, cocontraction of the abdominals and hamstrings to position the pelvis, smooth articulation of the spine to create a C curve, activation of the oblique muscles, and cocontraction of the abdominals when extending (arching) the back. The goal is to learn and rehearse these motor skills so that they can easily be applied to related exercises. Remember that in Pilates the emphasis is on how you perform the movements. Quality and precision of execution are important. Simply following the exercise steps is not enough. Application of the technique cues and principles discussed under exercise notes is essential for gaining the full benefit of each exercise.

Although the exercises in this chapter do not appear in Return to Life Through Contrology and are not regarded as part of the classic repertoire, they have become standards in many schools of Pilates and are frequently used in mat classes. Despite all being fundamental, the exercises in this chapter are ordered in terms of increasing difficulty. Therefore, the exercises begin with abdominal strengthening and trunk stabilization in which spinal flexion occurs in a stable supine position, followed by lateral flexion in a less stable side-lying position. Spinal rotation is then added. Lastly, when the trunk muscles are adequately prepared, spinal extension is performed.

Because of their placement at the beginning of the workout, each of these exercises should be executed with low to moderate intensity so that the focus is on warming up and finding inner technique connections rather than on maximizing strength gains. Although this order is recommended while learning the skills demanded by these exercises, once adequate proficiency has been achieved, the sequencing and position of some of these exercises in a workout can be changed to meet individual profiles.

Pelvic Curl

Execution

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.

Targeted Muscles

Spinal flexors: rectus abdominis, external oblique, internal oblique

Anterior spinal stabilizer: transversus abdominis

Pelvic floor muscles: coccygeus, levator ani (pubococcygeus, puborectalis, iliococcygeus)

Hip extensors: gluteus maximus, hamstrings (semitendinosus, semimembranosus, biceps femoris)

Accompanying Muscles

Spinal extensors: erector spinae

Knee extensors: quadriceps femoris

Shoulder extensors: latissimus dorsi, teres major, posterior deltoid

Technique Cues

• In step 2, at the beginning of the exhale, draw the pelvic floor muscles upward and the abdominal wall in toward the spine. This will encourage use of the transversus abdominis just before using the other abdominal muscles that posteriorly tilt the pelvis and flex the spine sequentially from bottom to top as it is curled off the mat.

• Press the feet into the mat, and think of gently pulling the sit bones toward the knees while lifting the bottom of the pelvis to emphasize using the hip extensors, especially the hamstrings. The knee extensors also help raise the thighs upward from the start position.

• In step 3, press the arms down into the mat so the shoulder extensors aid with lifting the upper trunk. Also, focus on activating the upper spinal extensors to align the upper trunk with the shoulders and knees.

• Throughout the movement, keep the knees facing forward.

• Imagine. To help achieve the desired motion of the pelvis and spine in step 2, imagine that the area between the rib cage and pubic bone is a shallow bowl. Scoop the abdominal wall inward to touch the inside of the shallow bowl, and then slowly rock that bowl by lifting the bottom rim toward the rib cage.

Exercise Notes

Pelvic Curl can help you learn to focus on activating the deep pelvic floor and transversus abdominis muscles, to sequentially articulate the pelvis and spine, and to cocontract the muscles of the powerhouse in the desired manner.

Focus on the hamstrings. Appropriate contraction of the hamstring muscles is vital for the desired articulation of the pelvis and spine in this exercise. The three hamstring muscles (see the illustration) run down the back of the thigh from the sit bones to below the knee. In this exercise and other similar supine Pilates exercises in which the feet are on the mat in a closed kinematic chain (see chapter 3), the hamstrings produce hip extension by lifting the pelvis rather than moving the legs. Focusing on lifting the bottom of the pelvis can help utilize these important muscles and prevent the common error of lifting the trunk as a rigid unit or arching the lower back. The coordinated contraction of the hamstrings with the abdominals, termed the abdominal–hamstring force couple (discussed in chapter 3), also serves another important role of helping to rotate the top of the pelvis backward in a posterior pelvic tilt. This function is used in the early part of the exercise to curl the pelvis and later to help maintain a neutral position of the pelvis and assist in countering hyperlordosis.

Chest Lift

Execution

1. Start position. Lie supine with the knees bent and the feet flat on the mat and hip-width apart. Interlace the fingers behind the head, and bend the elbows so they point sideways. Tilt the chin slightly down toward the chest.

2. Exhale. Slowly curl the head and upper trunk up, as shown in the main muscle illustration, so that the scapulae lift off the mat while the back portion of the waistline establishes contact with the mat. Pull in the abdominal wall farther, deepening the forward curved position of the trunk.

3. Inhale. Pause.

4. Exhale. Slowly lower the trunk and head to return to the start position. Repeat the sequence 10 times.

Targeted Muscles

Spinal flexors: rectus abdominis, external oblique, internal oblique

Accompanying Muscles

Anterior spinal stabilizer: transversus abdominis

Technique Cues

• In step 2, at the beginning of the exhale, draw the abdominal wall in toward the spine to encourage use of the transversus abdominis just before using the other abdominals—rectus abdominis, external obliques, and internal obliques—to tilt the pelvis slightly posteriorly, and then flex the spine sequentially from top to bottom.

• Once the head has been lifted in step 2, keep the chin the same distance from the chest and focus on using the abdominals to bring the front of the lower rib cage down toward the front of the pelvis.

• To help target the abdominals, keep the elbows back in line with the shoulders as the trunk is raised into flexion. Avoid swinging the elbows forward, pulling on the head, or using excessive momentum to help raise the trunk.

• During the pause in step 3, focus on lateral breathing (see chapter 1) so that the abdominal wall can remain pulled in and the torso held at the same height despite the inhale.

• In step 4, use the abdominals to control lowering the trunk back to the start position. Focus on pressing one vertebra at a time sequentially into the mat, from the lower to the upper spine, as opposed to lowering rigid sections of the spine.

• Imagine. To help achieve the desired flexion of the spine in step 2, imagine the upper and middle trunk curving up and around an exercise ball, with the curve evenly distributed rather than exaggerated in any one region.

Exercise Notes

This relatively simple exercise offers a perfect opportunity to learn how to effectively recruit the abdominals for strength gains and for use in more challenging abdominal exercises.

Create a C curve. The key concept to remember is this: Since the abdominals span between the rib cage and pelvis, effective overload to the abdominals for this exercise entails maximal flexion from the upper back to the beginning of the lower back rather than excessive flexion of the neck or hips. Achieving the desired distributed curvature of the spine, while pulling the abdominal wall in so that it is as concave as possible, can be referred to as creating a C curve of the spine. This terminology will be used to simplify related exercise descriptions.

Variation

As you lift into forward flexion, keep the pelvis in a neutral position instead of creating a slight posterior tilt. This will demand skilled cocontraction of the abdominals and spinal extensors.

Leg Lift Supine

Execution

1. Start position. Lie supine with the knees bent so the lower legs form approximately 90-degree angles relative to the thighs and the feet are flat on the mat and hip-width apart. The arms are by the sides with the palms facing down.

2. Exhale. Raise one leg until the knee is just above the hip joint, the thigh perpendicular to the mat, while maintaining the 90-degree angle at the knee joint as shown in step 2.

3. Inhale. Lower the leg until the toes touch the mat, while still maintaining the 90-degree angle at the knee joint. Repeat the sequence five times with the same leg. Place the foot fully down on the mat. Perform the same sequence with the opposite leg.

Targeted Muscles

Hip flexors: iliopsoas, rectus femoris, sartorius, pectineus, tensor fascia latae, gracilis

Anterior spinal stabilizers: rectus abdominis, external oblique, internal oblique, transversus abdominis

Accompanying Muscles

Knee extensors: quadriceps femoris

Technique Cues

• Focus on keeping the pelvis stationary and the weight evenly distributed on both sides of the pelvis as the hip flexors raise the leg in step 2 and then eccentrically lower the leg in step 3. Avoid shifting weight to the opposite side of the pelvis as the leg lifts and lowers.

• As the leg lifts in step 2, contract the knee extensors to maintain the desired 90-degree angle of the knee and prevent the lower leg from dropping down because of gravity.

• Emphasize isolating the movement to the hip joint, with the leg lifting and lowering with no changes in knee angle or in rib cage or pelvic alignment.

• Imagine. To help achieve the desired isolated movement, imagine the cover of a heavy textbook easily closing and opening with no effect on the very heavy and stable body of the text. The leg acts like the cover of the book. You should feel a sense of lightness in the moving leg.

Exercise Notes

This simple but valuable exercise focuses on using the necessary muscles, primarily the abdominals, to keep the trunk stable as the lower limbs move.

Trunk stabilization with hip flexion. In this exercise, the abdominals are working as stabilizers rather than movers. Because the upper attachments of many of the hip flexors are on the sides of the lower spine and the front of the pelvis, when they forcibly contract to lift the leg, they also tend to arch the lower back and pull the front of the pelvis forward into an anterior pelvic tilt, unless adequate stabilization of the pelvis and spine is provided by the abdominals. Research suggests that the transversus abdominis (see the illustration) plays a particularly important role in stabilization when the limbs move. The fibers of the transversus abdominis run almost horizontal. Therefore, focusing on pulling the deep abdominal wall inward toward the spine can help activate this muscle to maintain the desired neutral position of the pelvis. Building the skill of using the abdominals and other muscles of the powerhouse to stabilize the trunk is an essential goal of Pilates and vital for proper execution of some of the advanced landmark Pilates exercises, such as Teaser.

Leg Lift Side

Execution

1. Start position. Lie on one side, with the bottom arm and both legs straight and in line with the trunk. The head is resting on the bottom arm. The top arm is bent, with the palm on the mat in front of the torso and the fingers pointing toward the head.

2. Exhale. Raise both legs as one unit toward the ceiling, and then lift the legs higher by laterally flexing the spine. See the main muscle illustration.

3. Inhale. Lower the legs until they are just above, but not touching, the mat. Repeat the sequence 10 times. Lower the legs to the start position. Perform the same sequence on the opposite side.

Targeted Muscles

Lower spinal lateral flexors: external oblique, internal oblique, quadratus lumborum, erector spinae (spinalis, longissimus, iliocostalis), semispinalis, deep posterior spinal group (multifidus, rotatores, intertransversales), iliopsoas

Accompanying Muscles

Hip abductors of top leg: gluteus medius, gluteus minimus

Hip adductors of bottom leg: adductor longus, adductor brevis, adductor magnus, gracilis

Knee extensors: quadriceps femoris

Ankle–foot plantar flexors: gastrocnemius, soleus

Technique Cues

• In step 2, move the legs as one unit by using the hip adductors to pull the bottom leg up against the top leg, while the hip abductors of the top leg raise the top leg. The knee extensors keep both knees straight as the ankle–foot plantar flexors keep both feet pointed.

• Initially focus on the movement occurring at the hip joints while the trunk stays stationary, with the waist lifted off the mat. Then, to lift the legs higher, emphasize activating the lateral flexors of the spine by bringing the side of the pelvis closer to the rib cage on the upper side of the body while the legs reach up toward the ceiling. In this phase, the waist will lower toward the mat as the spine laterally flexes and the pelvis laterally tilts.

• The hips should remain stacked, with the top hip bone vertically above the lower hip bone. Avoid rocking backward or forward as the legs move.

• Imagine. To help achieve correct form and movement quality, imagine an archer’s bow being pulled tight. As the legs arc up toward the sky, they create a bow shape together with the trunk.

Exercise Notes

Although this exercise can provide some toning benefits for both the hip adductors and abductors, its primary purpose is to strengthen the lateral flexors of the spine and develop essential skills for core stability.

Spinal lateral flexion. Ideally, lateral flexion involves bending the spine directly to the side. This movement requires a finely coordinated simultaneous contraction of muscles located in the front, primarily the obliques and iliopsoas; muscles located on the side, primarily the quadratus lumborum; and muscles located in the back, including the erector spinae, semispinalis, and components of the deep posterior spinal group (see the illustration). With optimal form, the obliques do most of the work, with the back muscles firing just sufficiently to keep the trunk from flexing forward. However, it is common to use too much activation of the back muscles, causing the lower back to arch. In such cases, allow the feet to come forward slightly, and emphasize pulling the abdominal wall inward so the body is in a slight banana shape when viewed from the top to facilitate a more desired use of the obliques.

Leg Pull Side

Execution

1. Start position. Lie on one side, with the bottom arm and both legs straight and in line with the trunk. The head is resting on the bottom arm. The top arm is bent, with the palm on the mat in front of the torso, the fingers pointing toward the head. The bottom leg is resting on the mat, and the top leg is held slightly higher than the top hip. Feet are pointed.

2. Exhale. Raise the bottom leg toward the top leg, ideally until touching. See the main muscle illustration.

3. Inhale. Lower the bottom leg until it lightly touches the mat. Repeat the sequence 10 times. After the last repetition, lower the bottom leg to rest fully on the mat. Perform the same sequence on the other side.

Targeted Muscles

Hip adductors of bottom leg: adductor longus, adductor brevis, adductor magnus, gracilis, pectineus

Accompanying Muscles

Lateral spinal stabilizers and lower spinal lateral flexors: external oblique, internal oblique, quadratus lumborum, erector spinae

Hip abductors of top leg: gluteus medius, gluteus minimus

Knee extensors: quadriceps femoris

Ankle–foot plantar flexors: gastrocnemius, soleus

Technique Cues

• Focus on using the hip abductors to keep the top leg stationary. Use the hip adductors to raise the bottom leg in step 2, and then use them eccentrically to lower the bottom leg in step 3. The knee extensors keep the knees straight while the ankle–foot plantar flexors keep the feet pointed throughout the exercise.

• Keep the waist lifted off the mat and the pelvis still throughout the exercise. By keeping the bottom of the rib cage close to the side of the pelvis with the waist lifted, the spinal lateral flexors of the lower side of the body can be used to limit the lateral tilt of the pelvis. This facilitates greater overload to the hip adductors.

• Keep the hips stacked, and avoid rocking the top hip bone backward or forward.

• Imagine. To help achieve the desired isolated movement of the leg at the hip joint, imagine an open protractor facing sideways, with the bottom arm of the protractor rising to close the angle.

Exercise Notes

The purpose of this exercise is to improve muscle strength or tone in the hip adductors while maintaining trunk stability in this challenging side-lying position. If trunk stability cannot be adequately maintained and the back arches or the hips rock back and forth, move the legs slightly forward to create a banana shape, as described in Leg Lift Side (page 58).

The hip adductors (see the illustration) are a massive group of muscles that includes the adductor longus, adductor brevis, adductor magnus, gracilis, and pectineus. All of these, except the pectineus, are considered prime movers for hip adduction. Because of their location, the hip adductors are often referred to as the inner thigh muscles. This popular exercise tones the inner thighs and helps counter the jiggle that can occur during walking when these muscles are out of shape.

The hip adductors are used to raise the bottom leg off the mat in any side-lying exercise, such as Leg Lift Side (page 58). They also are used to keep the legs together in many Pilates exercises in which both legs move in unison, such as Jackknife (page 123) and Corkscrew (page 168). This use of the adductors to keep the legs together as the legs reach out is a key element in achieving the long and connected line of the legs that is vital to the Pilates aesthetic.

Spine Twist Supine

Execution

1. Start position. Lie supine with the hips and knees at 90-degree angles so that the knees are directly above the hip joints and the lower legs are parallel to the mat. Feet are gently pointed. The arms are straight down by the sides, with the palms facing down.

2. Exhale. Pull the abdominal wall in, and perform a slight posterior pelvic tilt. Gently pull the inner thighs together.

3. Inhale. Rotate the middle and lower trunk so that the pelvis and knees move as a single unit to one side as shown in the main muscle illustration.

4. Exhale. Rotate back to center.

5. Inhale. Rotate the middle and lower trunk to the opposite side as shown, moving the pelvis and knees as one unit.

6. Exhale. Rotate back to center. Repeat the sequence five times each direction.

Targeted Muscles

Spinal flexors and rotators: rectus abdominis, external oblique, internal oblique, transversus abdominis

Accompanying Muscles

Spinal extensors and rotators: erector spinae

Hip flexors: iliopsoas, rectus femoris

Hip horizontal adductors: adductor longus, adductor brevis, adductor magnus, pectineus

Knee extensors: quadriceps femoris

Ankle–foot plantar flexors: gastrocnemius, soleus

Technique Cues

• In step 2, focus on drawing the transversus abdominis inward and using the obliques to rotate the trunk so the pelvis and knees go to one side while the shoulders remain stationary and in full contact with the mat in step 3.

• Further deepen the flexion of the lower spine before pulling the lower side of the pelvis back toward the opposite side of the rib cage in step 4. This encourages greater use of the obliques, not the spinal extensors, to produce the rotation.

• Pull the knees together gently, using the hip horizontal adductors to keep the bottom leg lifted as the spine rotates. Keep the knees aligned with the center of the pelvis as the ankle–foot plantar flexors keep the feet pointed throughout the exercise.

• Maintain the 90-degree angles at the hips and knees throughout the exercise.

• Imagine. To help achieve the desired motion of the pelvis and spine, imagine a steering wheel turning slowly in one direction and then the other.

Exercise Notes

This exercise is valuable for learning to rotate the pelvis and lower back while maintaining desired alignment of the core. When rotating the spine, the common error is to excessively arch the back so the spinal extensors, not the abdominals, primarily affect the movement. Learning to use the transversus abdominis and obliques in this supine position can help protect the spine from injury when spinal rotation is used, particularly in more challenging exercises or during athletic activities.

Tabletop position. The tabletop position shown in step 1 is one of the fundamental supine positions used in Pilates. In this position, the hip flexors help maintain the 90-degree angles at the hips and prevent the legs from moving away from the chest. The knee extensors are used to create the 90-degree angles at the knees and to prevent the lower legs from dropping down to the mat.

Variation

Keep the pelvis in a neutral position as the spine rotates and the pelvis tips onto its side. This will change the desired muscle recruitment to an intricate cocontraction of the abdominals and the spinal extensors.

Chest Lift With Rotation

Execution

1. Start position. Start in the same position as for Chest Lift (page 54), supine with the knees bent and feet flat on the mat and hip-width apart. Interlace the fingers behind the head, and bend the elbows so they point to the sides. The chin is tilted slightly down toward the chest.

2. Exhale. Slowly curl the head and upper trunk up as shown so that the scapulae lift off the mat while the back of the waistline contacts the mat.

3. Inhale. Pause.

4. Exhale. Rotate the upper trunk to one side. See the main muscle illustration.

5. Inhale. Rotate back to center.

6. Exhale. Rotate the upper trunk to the opposite side.

7. Inhale. Rotate back to center. Continue alternating the rotation 10 times (5 times each side) while the head and upper trunk remain lifted off the mat. On the last repetition, pause in the center, pulling the abdominal wall farther inward, and then slowly exhale while lowering the trunk and head to the start position.

Targeted Muscles

Spinal flexors and rotators: rectus abdominis, external oblique, internal oblique, transversus abdominis

Technique Cues

• Use the abdominals to maintain a slight posterior tilt of the pelvis, the desired C curve of the spine, and the desired height of the trunk off the mat while the upper trunk rotates from side to side.

• Once the head has been lifted in step 2, maintain the same degree of neck flexion with the elbows in line with the shoulders so that the focus is on using the obliques to rotate the upper trunk while the pelvis remains stationary in steps 4 through 7.

• Avoid bringing the elbows forward and pulling on the head, or bringing the chin farther down or forward.

• At the end of step 7, use the abdominals eccentrically to create a smooth, sequential lowering of the trunk and head back to the start position.

• Imagine. To help achieve the desired trunk rotation, imagine the trunk lifting as it rotates, like the swell of a wave. Keep both sides of the trunk long, and avoid bending the trunk to the side.

Exercise Notes

This basic exercise is valuable for developing the obliques, muscles essential for providing contour and tone in the abdominal area to the sides of the central rectus abdominis. The obliques also play a key role in trunk stability and prevention of lower back injury, and are fundamental to most athletic activities.

Oblique focus. Because many muscles can produce rotation, keeping the C curve with the spine flexed rather than flattening during rotation will effectively challenge the obliques. In addition, note that the upper portion of the external oblique runs from the outside of the rib cage diagonally down toward the central tendon, called the linea alba (see the illustration). In contrast, the internal oblique runs diagonally up to attach to the central tendon and the undersurface of the rib cage. So, when rotating the upper trunk to the left, focusing on bringing the right side of the rib cage toward the center and then the center toward the opposite hip bone (left ASIS) can help activate the desired right external and left internal oblique muscles. There should be a sensation of both sides of the abdominal area rigorously working as the upper trunk rotates. The transversus abdominis may also assist with rotation.

Variation

As the body lifts into forward flexion, keep the pelvis in a neutral position instead of creating a slight posterior tilt.

Back Extension Prone

Execution

1. Start position. Lie prone with the forehead on the mat and the arms by the sides with the palms pressing against the sides of the thighs, elbows straight. The legs should be together with the feet gently pointed.

2. Exhale. Lift the head, upper trunk, and middle trunk off the mat while keeping the legs together and the arms pressing against the sides. See the main muscle illustration.

3. Inhale. Slowly lower the trunk and head, returning to the start position. Repeat the sequence 10 times.

Targeted Muscles

Spinal extensors: erector spinae (spinalis, longissimus, iliocostalis), semispinalis, deep posterior spinal group

Accompanying Muscles

Anterior spinal stabilizers: transversus abdominis, internal oblique, external oblique, rectus abdominis

Hip extensors: gluteus maximus, hamstrings

Shoulder adductors: latissimus dorsi, pectoralis major

Elbow extensors: triceps brachii

Technique Cues

• In step 2, maintain abdominal support, and keep the legs together and in contact with the mat as the spinal extensors are used to raise the upper trunk.

• Focus on sequentially extending the back, vertebra by vertebra, starting from the top, particularly emphasizing the spinal extensors in the upper and middle back while continuing to reach the head out in line with the upper back.

• Continue pressing the arms against the sides using the shoulder adductors, particularly the latissimus dorsi and pectoralis major. Both of these muscles can also help depress the shoulders, so reaching the fingertips gently down toward the feet while the elbow extensors keep the elbows straight can help activate them. Recruitment of the latissimus dorsi is desirable because it is a key muscle for trunk stabilization.

• In step 3, use the spinal extensors eccentrically to control lowering the trunk, this time sequentially from bottom to top, while the abdominals continue to provide support.

• Imagine. To achieve the desired feeling of elongation, imagine a rubber band anchored at one end (your feet) being pulled out and up from the other end (the crown of your head).

Exercise Notes

The purpose of this exercise is to strengthen the spinal extensors, particularly the erector spinae, while working on developing the ability to simultaneously use the abdominals to help protect the lower back.

Abdominal support with spinal extension. Because the lower back, or lumbar, curve is concave posteriorly but the upper back, or thoracic, curve is concave anteriorly, the tendency is predominantly to arch the lower back when performing this and similar spinal extension exercises. Arching the lower back also tends to be linked with tilting the top of the pelvis forward to create an anterior pelvic tilt (see the first illustration below). However, pulling the lower attachment of the abdominals upward can produce rotation of the pelvis in the opposite direction, a posterior pelvic tilt (see the second illustration below). Think of gently pressing the pubic bone into the mat while the lower portion of the abdominals pulls up and in toward the spine to limit the amount of anterior pelvic tilt and reduce the stress to the vulnerable lower lumbar spine. This stabilization of the lower back also facilitates focusing on and strengthening the upper back muscles, which are key for preventing slumped posture. The hip extensors may also help stabilize the pelvis and prevent it from tilting forward excessively (the abdominal–hamstring force couple is discussed in chapter 3). Learning to use the abdominals to help stabilize the lower back in this basic exercise is essential for optimal execution of more challenging exercises involving spinal extension, such as Swimming (page 184) and Double Kick (page 181).