Some individuals with lower back pain tend to have over activation of their lumbar extensors with excessive lumbar extension and lack proper activation of the hip extensor muscles; such as the gluteus maximus and hamstrings. Usually this discrepancy is most prominent during hip extension motions.
I wanted to find information that will help modify this motor pattern during dynamic exercises and eventually functional tasks. I came across an article that focused on an abdominal drawing-in maneuver (ADIM). The idea is that while performing an ADIM when completing a hip extension exercise the lumbar extensors will not be as active and the hip extensor muscles will complete most of the task.
There are a couple theories to the cause of this adjustment in muscle activation with abdominal hollowing. One is less anterior pelvic tilt causes a poor length tension relationship for the lumbar extensors and a more optimal one for the hip extensors. Another theory is due to reciprocal inhibition, which means that when the agonist muscles (e.g. abdominal muscles) are activated the antagonist muscles (e.g. lumbar extensors) naturally become less active, so the hip extensor muscles must take over to complete the task.
(Click the link below for access to the article)
Purpose: To measure the electromyographic (EMG) signal amplitude of the hip extensors and erector spinae and the angle of the anterior pelvic tilt during hip extension in the prone position.
Methods: The researchers examined two groups of subjects completing a prone hip extension with the knee extended with an ADIM or without an ADIM. They measured the muscle activation of the erector spinae and the gluteus maximus and medial hamstring on the dominant side. They had the subjects sustain the hip extension for 5 seconds. They placed a pressure cuff underneath the abdomen inflated to 70 mmHg and instructed the subjects to maintain the pressure at about 60 mmHg during the movement.
Results: The researchers compared the outcome measures of hip extension without an ADIM to hip extension with an ADIM and found a significant decrease in erector spinae activation (49% to 17% MVIC), significant increase in gluteus maximus (24% to 52% MVIC) and medial hamstring activation (47% to 58% MVIC), and a decrease in anterior pelvic tilt (10 degrees to 3 degrees). *MVIC = maximal voluntary isometric contraction
Limitations: The data cannot be generalized because the subjects were only healthy and no unhealthy subjects were studied. There is a potential for the EMG to pick up signals from adjacent muscles. The researchers did not differentiate muscle activation between abdominal muscles, the diaphragm, and the pelvic floor with the abdominal drawing-in maneuver. Finally, the lumbopelvic hip movement patterns were not measured to see how much movement at those segments were occurring.
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