This test involves the lower fibers of the rectus abdominals (attached to the pubic crest and symphysis). One must remember this is a muscle that performs either flexes the vertebral column with the pelvis fixed; however, with the thorax fixed, the pelvis will move toward the thorax.
Anterior trunk flexion by the lower abdominals focuses on one’s ability to use these muscles to flex the lumbar spine by flattening the low back on the testing surface and then holding this flat back position as the subject lowers both legs to the testing surface.
Starting Position for Abdominal Testing
The subject lies prone on a rigid, flat testing surface. Forearms are folded across the chest or hands behind the head. When the low back is pushed into the testing surface the pelvis will be in the same tilted position as when performing the trunk flexion test (approximately 10 degrees downward.
Fixation During Testing
No fixation of the legs (holding the legs down) is needed because this test determines the abdominal’s ability to fix/stabilize the pelvis while the subject lowers the legs to the testing surface.
Testing Movement
Have the subject raise both legs to 90 degrees of the trunk (straight up position). Knees should be straight when legs are in position. Have the subject push the lower back into the testing surface. The position of the low back should be stabilized and maintained throughout the entire test. Head and arms remain fixed as well.
Applying Resistance During Abdominal Testing
Any force experienced by the hip flexor muscles and the lowering leg movement will cause the pelvis to anteriorly tilt and acts as a strong resistance against the abdominal muscles. The abdominal muscles are attempting to hold the pelvis in the posterior tilted position as the subject lowers the legs slowly to the testing surface. Both the abdominal and hip flexor muscles are lengthening (eccentric action) as the legs are lowered causing the legs to become a long lever arm as they are lowered and causing the resistance to increase (external force or load on the muscles). The subject attempts to hold the pelvis in the pushed down position as the legs are lowered.
The tester should position their hand on the small of the subject’s back to ensure the pelvis is held in the correct position. Another tool to measure force is a blood pressure cuff to see if the starting force on the cuff is maintained throughout the leg lowering process. Any decrease in force on the hand or cuff should be noted based on the angle of the legs as they are lowered. The decrease in force indicates the test should stop and the leg angle measured (or approximated) for determining the status of these muscles. The positions of the legs (angles of the legs during lowering) are as follows:
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- 90 degrees (start position)
- 75 degrees (fair)
- 60 degrees (fair+)
- 45 degrees (good-)
- 30 degrees (good)
- 15 degrees (good+)
- 0 degrees (normal)
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Please note the position of the legs as the lower back starts to rise from the testing surface. It should be stated that many subjects have no problem lowering their legs to the testing surface but their lower back may rise from the testing surface during the vast majority of the test. This is an indication the subject has markedly weak abdominals but possesses very strong hip flexor muscles.
Remember: Each position verified at any angle is indicative if the lower back is still pressed into the testing surface. If the lower back pressure/force into the testing surface decreases the test, at that angle, is complete. Again, the subject may be able to lower legs to surface with the lower back arched but this is an indication of markedly weak abdominals and very strong hip flexors.
To learn more about strength testing and how you can incorporate it into your training or coaching program, check out the NESTA NCCA Accredited Personal Fitness Trainer Certification and the Biomechanics Specialist Certification.
