Serratus Posterior Muscles: Understanding, Activating, and Strengthening

What exercises work the serratus posterior?

The serratus posterior muscles, consisting of the serratus posterior superior and serratus posterior inferior, are deep intrinsic back muscles primarily involved in respiration and spinal stability. While not directly targeted with isolation exercises like major muscle groups, they are activated synergistically during specific breathing exercises, spinal extension movements, and core stability drills.

Understanding the Serratus Posterior Muscles

The serratus posterior muscles are two thin, quadrilateral muscles located in the superficial layer of the intrinsic back musculature, deep to the rhomboids and latissimus dorsi. Their primary roles are often overlooked but are crucial for efficient respiration and maintaining spinal integrity.

• Serratus Posterior Superior (SPS):

  • Location and Attachments: Originates from the nuchal ligament and the spinous processes of C7-T3, inserting onto the upper borders of ribs 2-5, just lateral to their angles.
  • Primary Actions: Elevates the upper ribs, assisting in forced inspiration (inhalation). It plays a role in expanding the chest cavity.
  • Functional Relevance: Important for deep breathing, especially during physical exertion or in conditions like asthma where accessory breathing muscles are heavily recruited.

• Serratus Posterior Inferior (SPI):

  • Location and Attachments: Originates from the spinous processes of T11-L2, inserting onto the lower borders of ribs 9-12, just lateral to their angles.
  • Primary Actions: Depresses the lower ribs, assisting in forced expiration (exhalation). It helps to compress the abdominal contents and stabilize the lower thoracic spine during trunk movements.
  • Functional Relevance: Contributes to expelling air from the lungs, providing stability to the thoracolumbar junction during lifting, bending, and twisting movements, and supporting core bracing.

Direct vs. Indirect Activation

It's important to understand that the serratus posterior muscles are not prime movers in the way that the pectorals or quadriceps are. They are deep, postural, and respiratory muscles that act as synergists or stabilizers. Therefore, "isolating" them in the traditional sense is challenging and often not the most effective approach. Instead, exercises that emphasize their primary functions—rib movement and spinal stability—will engage them most effectively.

Exercises Targeting the Serratus Posterior Superior

Exercises that promote deep inhalation and thoracic spine extension will engage the SPS. The focus here is often on mobility and breathing mechanics rather than heavy resistance.

• Diaphragmatic Breathing with Rib Expansion:
  • Lie supine with one hand on your chest and one on your abdomen. Focus on breathing deeply, allowing your abdomen to rise, followed by an expansion of your lower and then upper rib cage. The SPS assists in the active elevation of the upper ribs during the latter phase of a deep inhale.
• Cat-Cow Pose (Extension Phase):
  • From a tabletop position, arch your back, dropping your belly towards the floor, lifting your chest, and looking up. This thoracic extension movement, coupled with a deep inhale, can activate the SPS as it helps elevate the upper ribs.
• Overhead Reaches and Stretches:
  • Gentle overhead arm movements, especially those that encourage thoracic extension and rib cage expansion, can involve the SPS. Examples include reaching overhead while standing or performing a child's pose with arms extended.

Exercises Targeting the Serratus Posterior Inferior

The SPI is involved in depressing the lower ribs and stabilizing the thoracolumbar spine. Exercises that require spinal extension, core stability, and controlled trunk movements, particularly those involving the lower back and core, will activate the SPI.

• Back Extensions (Hyperextensions):
  • Performed on a Roman chair or stability ball, back extensions primarily target the erector spinae, glutes, and hamstrings. The SPI works synergistically to stabilize the lower thoracic and lumbar spine during the extension phase, especially if you focus on a controlled contraction and slight lower rib depression at the peak.
• Good Mornings:
  • With a barbell across your upper back (or using bodyweight), hinge at your hips, keeping a slight bend in your knees and a neutral spine. The SPI contributes to the stability of the thoracolumbar region as you lower and raise your torso, resisting excessive flexion.
• Romanian Deadlifts (RDLs):
  • Similar to good mornings, RDLs emphasize hip hinging while maintaining a neutral spine. The SPI, along with the erector spinae and core muscles, plays a crucial role in stabilizing the spine throughout the movement, particularly during the eccentric (lowering) phase.
• Bird-Dog:
  • From a tabletop position, extend one arm forward and the opposite leg backward, maintaining a stable core and neutral spine. This exercise challenges core stability and spinal control, engaging the SPI as a stabilizer to prevent unwanted trunk rotation or excessive arching.
• Cable Pullovers (with specific intent):
  • While primarily a latissimus dorsi exercise, performing cable pullovers with a focus on depressing the lower ribs and maintaining a strong core brace can indirectly engage the SPI, particularly during the eccentric control phase. The key is to emphasize the role of the core and lower back in stabilizing the trunk.

Importance of Core and Spinal Stability for Serratus Posterior Function

Both serratus posterior muscles are integral components of the body's deep core stability system. They work in conjunction with the diaphragm, pelvic floor, transverse abdominis, and multifidus to create intra-abdominal pressure and provide a stable foundation for movement. Therefore, a comprehensive approach to strengthening these muscles involves:

• Integrated Core Training: Exercises that challenge the entire core unit, promoting coordinated contraction of deep abdominal and back muscles.
• Mindful Breathing: Incorporating deep, diaphragmatic breathing into daily activities and exercise routines enhances the function of all respiratory muscles, including the serratus posterior.
• Postural Awareness: Maintaining good posture, especially during prolonged sitting or standing, helps to prevent these muscles from becoming weak or dysfunctional.

Integration into Training Programs

Rather than dedicating specific "serratus posterior days," these muscles are best trained through a holistic approach that integrates functional movements, core stability, and conscious breathing.

• Warm-ups: Incorporate thoracic mobility drills and deep breathing exercises.
• Compound Lifts: Emphasize proper bracing and spinal stability during exercises like deadlifts, squats, and overhead presses.
• Accessory Work: Include exercises like back extensions, good mornings, and bird-dogs to specifically target spinal erectors and stabilizers.
• Recovery and Mobility: Regular stretching and mobility work for the thoracic spine and rib cage can support optimal serratus posterior function.

Considerations and Best Practices

• Form Over Weight: Given their role as stabilizers, prioritize correct form and controlled movements over lifting heavy weights, especially for exercises like good mornings and RDLs.
• Breathing Mechanics: Pay close attention to your breathing during all exercises. Consciously engaging your diaphragm and observing rib cage movement can enhance activation.
• Listen to Your Body: Any sharp pain in the back or rib cage area should be a signal to stop and assess your form or consult a healthcare professional.
• Consult a Professional: If you have specific concerns about back pain, breathing difficulties, or want to ensure proper exercise technique, consult with a qualified personal trainer, physical therapist, or kinesiologist.

By understanding the functional anatomy of the serratus posterior muscles and incorporating exercises that support their roles in respiration and spinal stability, you can contribute to a more resilient, functional, and injury-resistant body.