Transversus Abdominis

A Deep Core Muscle for Lumbopelvic Control and Athletic Movement

The transversus abdominis (TrA) is one of the deepest muscles of the abdominal wall and plays an important role in controlling the lumbar spine and pelvis during movement.

Its function extends far beyond simply “drawing the stomach in.” The TrA can activate in anticipation of limb movement and contributes to intra-abdominal pressure, thoracolumbar fascial tension, and lumbopelvic stiffness as part of the body’s anticipatory postural control system.¹⁻³

For athletes, this makes the TrA less of a primary force-producing muscle and more of a muscle that helps create an efficient foundation from which the extremities can produce and transfer force.

Anatomy of

the Transversus Abdominis

Origin

The TrA originates primarily from the:

• Iliac crest
• Inner surfaces of the lower six costal cartilages
• Thoracolumbar fascia⁷

It lies deep within the lateral abdominal wall. Posteriorly, it is continuous with the thoracolumbar fascia, while anteriorly its fibers transition into the transversus abdominis aponeurosis and rectus sheath.⁸˒⁹

Insertion

The TrA inserts primarily into the:

Linea alba.⁷⁻⁹

Through this broad fascial connection, contraction of the TrA can increase tension across the abdominal wall and contribute to trunk stiffness.

Actions

Primary functions of the TrA include:

• Compressing the abdominal contents
• Reducing abdominal cross-sectional area
• Increasing intra-abdominal pressure
• Tensioning the thoracolumbar fascia
• Contributing to lumbar and pelvic stability⁷˒⁸˒¹⁰

The TrA also works synergistically with the:

• Multifidus
• Diaphragm
• Pelvic floor

as part of the deeper trunk stabilization system.³˒¹¹

Exercise 1 | Abdominal Drawing-In Maneuver

The abdominal drawing-in maneuver is one of the most commonly studied strategies for selectively recruiting the TrA.¹¹⁻¹³

How It Is Performed

While maintaining a neutral lumbar position, gently draw the lower abdominal wall inward without aggressively bracing or holding the breath.

Breathing should remain relaxed.

Why It May Be Useful

ADIM can help an athlete learn to recruit the deeper abdominal musculature without relying excessively on the more superficial trunk muscles.¹¹⁻¹³

Because the TrA is deep and difficult to directly palpate or voluntarily isolate, feedback can be useful during early motor learning.

Examples include:

• Ultrasound imaging
• Pressure biofeedback
• Visual feedback¹²˒¹³

ADIM is therefore best viewed as a motor-control exercise, rather than a high-level athletic strength exercise.

Exercise 2 | Dead Bug

The Dead Bug progresses TrA training from an isolated contraction toward maintaining trunk and pelvic control while the extremities move.

Instead of simply asking the athlete to “activate the core,” the exercise requires the athlete to:

maintain lumbopelvic position while producing independent arm and leg movement.

In comparisons of Pilates-based exercises, the Dead Bug produced one of the largest increases in TrA muscle thickness.¹⁴

This makes it a useful transition between isolated motor-control training and more dynamic athletic tasks.

Exercise 3 | Bird Dog

The Bird Dog requires the athlete to maintain trunk and pelvic control while extending the opposite arm and leg.

Studies examining hollowing-based stabilization exercises have reported substantial TrA recruitment during Bird Dog and Side Plank variations.²

The Bird Dog also requires coordination among the:

• TrA
• Multifidus
• Hip musculature
• Scapular stabilizers

making it particularly useful when progressing from isolated TrA activation toward integrated trunk control.

< Take-Home Message >

The transversus abdominis is a deep abdominal muscle that contributes to intra-abdominal pressure, thoracolumbar fascial tension, and control of the lumbar spine and pelvis.³˒⁷˒⁸

For athletes, its importance is not simply how strongly the muscle can contract in isolation.

What matters more is whether the TrA can contribute appropriately to trunk control while an athlete runs, jumps, throws, changes direction, or produces force through the extremities.

Early training may include ADIM or breathing-based strategies to improve motor control, followed by exercises such as the Dead Bug, Bird Dog, and Side Plank, and ultimately more dynamic and sport-specific tasks.²˒¹⁰⁻¹⁵

The evidence should also be interpreted cautiously.

Because the TrA is a deep muscle, direct EMG research is technically challenging, and studies vary considerably in methodology.¹⁹ Therefore, current evidence does not justify labeling one exercise as the single “best” TrA exercise or assuming that isolated TrA weakness is the cause of an athlete’s symptoms.

The ultimate goal is not simply to activate the TrA.

It is to develop a trunk that can efficiently stabilize, transfer force, and adapt to the demands of athletic movement.