Effects of Lumbosacral Joint Mobilization/Manipulation on Lower Extremity Muscle Neuromuscular Response

It is well known that musculoskeletal dysfunction at one joint is not limited to the joint itself and can be related to dysfunction at joints proximal or distal in the kinetic chain. Recent research has focused on the relationship of altered lower extremity kinematics and common musculoskeletal pathologies.

Pain is often associated with musculoskeletal pathologies and is one of the strongest stimuli affecting functional activities in a negative manner. Following injury or chronic dysfunction, inhibitory neurons decrease the ability of musculature to fully recruit excitatory motor neurons. This can lead to aberrant movement patterns and different activation of muscles. Muscle inhibition has been attributed as a possible source of altered motor activation patterns. Pain can be a result or cause of musculoskeletal dysfunction and does not necessarily precede inhibition, but can have a contributing effect. The presence of muscle inhibition is considered a limiting factor in the rehabilitation of musculoskeletal pathologies. If muscle inhibition is properly addressed, individuals and athletes alike, should be able to more appropriately meet the demands of the activities with a decreased risk of future injury.

One technique used to determine presence of muscle inhibition is to measure the ability of the muscle to produce a maximal voluntary isometric contraction and compare values with the ability of the contralateral muscle. Since the contralateral limb may also experience muscle inhibition,it is difficult to obtain an accurate measurement of the amount of muscle inhibition occurring in the ipsilateral limb. A suggested solution is utilize the burst-superimposition technique which provides the muscle with a supramaximal stimulus to recruit any remaining muscle fibers which have not been stimulated.

Treatment of muscle inhibition is multifaceted. Utilization of manual therapy techniques such as joint manipulation or mobilization directed at the lumbopelvic region have been shown to be successful in disinhibiting lower extremity muscles. Previous studies have demonstrated sacroiliac joint manipulation disinhibited the quadriceps muscle in individuals with anterior knee pain. One of the limitations was these studies only observed an immediate decrease of quadriceps inhibition and the duration of the treatment effect was unknown. Effects of disinhibition of other lower extremity muscles and duration of disinhibition have not been determined at this time. It is also unknown what effects manual therapy treatments directed at the lumbopelvic region have on functional activities such as walking, squatting, or ascending/descending stairs. By examining these effects, we will be attempting to provide scientific evidence to validate common clinical practices in rehabilitative medicine.