The neutral spine is one of the cornerstones of low back and core rehabilitation. On first glance it is an awareness of lumbar flexion versus hip flexion and the cognizant use of the lumbar extensor musculature to support forward flexion.
Why is this important? The neutral spine goes hand in hand with teaching patients to bend from the hips and not from the low back, this is a subtle yet important concept we will delve into later on when discussing hip hinging and the posterior chain. Looking at the trunk when we have full forward flexion without a neutral spine or hip hinging we are essentially turning off the low back extensor muscles, these are the primary muscles which function to support your back against a forward flexion movement as well as protecting your vertebra from shearing forces which are when one vertebrae wants to move forward against another due to flexion forces. When you bend at the waist to pick up a box from the ground, for example, you are taking away your support system. The little support you are left with is the ligaments which surround your spine, these ligaments are not meant to be the only supporters of your trunk and will become damaged easily. Remember its not as often as patients think that they damage a ligament with a single high load event, more often it is the culmination of years of low load events done repeatedly which over time weaken the ligament until it finally fails.
Achieving and maintaining a neutral spine actively engages the trunk extensors such as the Iliocostalis, Longissimus and Multifidi, letting them properly take up the force of trunk flexion and taking that pressure off of the ligaments, joints and the spine itself.
So what is the neutral spine? The spinal column has natural curves to help with compressive forces. The lumbar spine has a natural curve which helps it sustain the weight of the body and deal with compression from daily activity such as standing, walking, sitting, etc.
A neutral spine simply means maintaining this natural curvature while performing your daily tasks, whether that means sitting all day or loading heavy boxes the neutral spine should be something you are aware of and maintain all the time.
Finding your neutral spine is simple. Put your shoulders against a flat wall, make sure your head, buttocks and feet are touching the same wall. This establishes your center of gravity which should run through your ears, shoulders, hips, knees and ankles. You should have a slight arch in your lower back, you should be able to just slide your hand in this space. If you cannot get your hand in there you may have a decreased lumbar curvature, and if you feel more space than your hand you may have an increased lumbar curvature. Either of these situations can spell trouble and it’s important to recognize them and correct them with your health care practitioner.
Finding neutral spine, note the slight low back curvature and space.
Once you find your neutral spine you need to incorporate it into your daily routine.
Here we can see a proper neutral spine when flexing forward. You can also note that there is hip hinging, most of the trunk flexion is from rotation at the hips and the left over rotation at the lumbar spine is supported by the trunk extensor musculature. This leaves very little force at the lumbar spine and puts the force where it belongs.
When properly utilizing hip hinging and the neutral spine we can draw a straight line from the upper back down to the buttocks region. Often when training patients we will tape a broomstick to them so they can feel when they are correctly bending forward with a proper neutral spine.
Twisting: To add to the lumbar spine stress commonly we also twist while we bend forward. This twisting of the lumbar spine gives us a much higher chance of injury. Part of the problem is the disc itself, the disc is make up of alternating layers of supporting ligaments. The alternate layers have oblique or diagonal lines of strength, that is the line of direction they are the strongest in. When we twist the lumbar spine we are only taking advantage of every other layer of the disc, cutting in half the discs protective strength. Trunk twisting with forward flexion also places a very high demand on the trunk musculature which does not have any powerful muscle action which counters the rotation type forces. By keeping a neutral spine we can offload some of the rotation forces to the extensor musculature. Once again this is typically a function of small loads repeated over long periods of time, something which may not hurt us at first but eventually weakens the structures and causes injury and resultant pain and dysfunction later on down the line.