Testing the Muscles of the Trunk and Pelvic Floor

Testing the Muscles of the Trunk and Pelvic Floor

Trunk Extension



Table 4-1


I.D. Muscle Origin Insertion
89 Iliocostalis thoracis

90 Iliocostalis lumborum

91 Longissimus thoracis

92 Spinalis thoracis (often indistinct)

93 Semispinalis thoracis

94 Multifidi

95, 96 Rotatores thoracis and lumborum (11 pairs)

97, 98 Interspinales thoracis and lumborum

99 Intertransversarii thoracis and lumborum

100 Quadratus lumborum

182 Gluteus maximus (provides stable base for trunk extension by stabilizing pelvis)    


Lumbar Spine

Grade 5 (Normal) and Grade 4 (Good)

Note: The Grades 5 and 4 tests for spine extension are different for the lumbar and thoracic spines. Beginning at Grade 3, the tests for both spinal levels are combined.


Grade 5 (Normal) and Grade 4 (Good):

The therapist distinguishes between Grade 5 and Grade 4 muscles by the nature of the response (see Figures 4-3 and 4-4). The Grade 5 muscle holds like a lock; the Grade 4 muscle yields slightly because of an elastic quality at the end point. The patient with Grade 5 back extensor muscles can quickly come to the end position and hold that position without evidence of significant effort. The patient with Grade 4 back extensors can come to the end position but may waver or display some signs of effort.

Alternative Grade 5 Sorensen Lumbar Spine Extension Test

The Biering-Sorensen test or Sorensen test is a global measure of back extension endurance capacity.1

Instructions to Patient:

“When I say ‘begin,’ raise your head, chest, and trunk from the table and hold the position as long as you can. I will be timing you. Let me know if you have any back pain.”

Helpful Hints

• Low levels of endurance of back muscles are reported as cause and effect of low back pain.2

• The Sorensen test has been validated as a differential diagnostic test for low back pain.3,4 Individuals with low back pain have significantly lower hold times than those without low back pain. In subjects with low back pain, the mean endurance time ranges from 39.55 to 54.5 seconds in mixed-gender groups (compared with 80 to 194 seconds for men and 146 to 227 seconds for women without pain).2

• The mean endurance time for all subjects (with and without low back pain) in one study was 113 ± 46 seconds.2 Men had higher mean endurance than women.

• Because average endurance times have not been established for older individuals, caution should be exercised when testing individuals aged 60 years and older.

• A significant difference was found in the endurance time across the age groups,2 indicating that a decrease in endurance time should be expected with increasing age. Some age-based norms are listed in Table 4-2.

• More recent data suggest that normative values vary by specific populations and by specific anthropomorphic characteristics such as body mass index and torso length.2,5

• The multifidus demonstrates more electromyogram (EMG) activity and faster fatigue rates than the iliocostalis lumborum.6

Lumbar and Thoracic Spine

Grade 3 (Fair)

Grade 2 (Poor), Grade 1 (Trace), and Grade 0 (Zero)

These tests are identical to the Grade 3 test except that the therapist must palpate the lumbar and thoracic spine extensor muscle masses adjacent to both sides of the spine. The individual muscles cannot be isolated (Figures 4-9 and 4-10).




Grade 0 (Zero):

No contractile activity.

Helpful Hints

• Tests for hip extension and neck extension should precede tests for trunk extension.

• When the spine extensors are weak and the hip extensors are strong, the patient will be unable to raise the upper trunk from the table. Instead, the pelvis will tilt posteriorly while the lumbar spine moves into flexion (low back flattens).

• If the hip extensor muscles are Grade 4 or better, it may be helpful to use belts to anchor hips to the table, especially if the patient is much larger or stronger than the testing therapist.

• When the back extensors are strong and the hip extensors are weak, the patient can hyperextend the low back (increased lordosis) but will be unable to raise the trunk without very strong stabilization of the pelvis by the therapist.

• If the neck extensors are weak, the therapist may need to support the head as the patient raises the trunk.

• The position of the arms in external rotation and fingertips lightly touching the side of the head provides added resistance for Grades 5 and 4; the weight of the head and arms essentially substitutes for manual resistance by the therapist.

• If the patient is unable to provide stabilization through the weight of the legs and pelvis (such as in paraplegia or amputee), the test should be done on a mat table. Position the subject with both legs and pelvis off the mat. This allows the pelvis and limbs to contribute to stabilization, and the therapist holding the lower trunk has a chance to provide the necessary support. (If a mat table is not available, an assistant will be required, and the lower body may rest on a chair.)

• The Modified Sorensen test is the Sorensen test but performed with arms at the patient’s sides.

Elevation of the Pelvis



Grade 5 (Normal) and Grade 4 (Good)

Grade 1 (Trace) and Grade 0 (Zero)

These grades should be avoided to ensure clinical accuracy. The principal muscle involved in pelvic elevation, the quadratus lumborum, lies deep to the paraspinal muscle mass and can rarely be palpated. In people who have extensive truncal atrophy, paraspinal muscle activity may be palpated, and possibly, but not necessarily convincingly, the quadratus lumborum can be palpated.

Trunk Lateral Endurance

Trunk Flexion



Trunk flexion has multiple elements that include cervical, thoracic, and lumbar motion. Measurement is difficult at best and may be done in a variety of ways with considerable variability in results.

The neck flexors should be eliminated as much as possible by asking the patient to maintain a neutral neck position with the chin pointed to the ceiling to avoid neck flexion.

Grade 5 (Normal)

Position of Therapist:

Standing at side of table at level of patient’s chest to be able to ascertain whether scapulae clear table during test (see Figure 4-18). For a patient with no other muscle weakness, the therapist does not need to touch the patient. If, however, the patient has weak hip flexors (refer to page 206), the therapist should stabilize the pelvis by leaning across the patient on the forearms (Figure 4-19).


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Aug 25, 2016 | Posted by in RHEUMATOLOGY | Comments Off on Testing the Muscles of the Trunk and Pelvic Floor
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