...instability or pain?  Well this past August another study was published showing that pain - independent of biomechanical impairments - can alter muscle recruitment and affect movement capability.

The study used the Active Straight Leg Raise (ASLR) test which is widely used clinically to assess the severity of lumbo-pelvic pain due to [the belief of] decreased stability of the sacroiliac joint (SIJ).  In a nutshell, a solution was injected in the pelvic region meant to cause pain.  Pain intensity, ASLR test difficulty and degree of perceived pain throughout the pelvis and lower limb were all assessed and documented.  Also electromyography (EMG) was used to identify recruitment of trunk and thigh muscles during the ASLR.  In turn, these were all done before, during and after pain provocation.

The results showed that pain provocation in the pelvic area increased the difficulty to perform the ASLR test, as well as, increased [requirement of] activity with the stabilizing trunk and thigh muscles.  There also was increased sensitivity to pressure on adjacent structures to the injection site.  Of note, the results showed outcomes similar to those people that are tested when experiencing low back pain.

What does this mean to you?  It is important to address pain and discomfort in the body in order to optimize movement.  It can be argued that instability in one area may be caused by the nervous system attempting to mediate a more important threat in an adjacent area.  It is doing this by altering the tissue state (muscle recruitment, tissue laxity, etc...) in order to accomplish the protection it deems necessary.  Interestingly, movement [therapeutically] applied in a way that is not threatening to the [protecting] nervous system helps to alleviate pain and restore function.