Low back pain is the most common physical ailment in the world. The majority of people will experience a low back pain episode at some point in their lives, often repetitively.

To efficiently move forward, our trunk must be forward-oriented. This comes from hip flexion, but core stability is required to keep us trending forward without falling backwards. This could be why the vast majority of ‘core stability’ exercises deal with the anterior abdominal muscles.

At the same time, the way we propel is through hip mobility. The hips drive upward and downward, but the bulk of our propulsion in a gravity-dependent world comes from hip extension. Pushing off powerfully from the gluteal muscles is the central motor to fast, powerful, and efficient running. That said, strong, efficient running requires this balance: flexion-dominant stability of the trunk, which provides a solid platform for powerful hip extension beneath and behind us. It is when we lose this balance that problems arise, often in the low back and pelvis.

Low Back Pain During Running: Tips For Ultramarathon Runners Pt. 1Low Back Pain: A Misfire in the System

When either hip mobility or trunk stability is lost, so is efficiency. With the former, if the hip cannot extend–either due to tightness or poor positioning–’the buck is passed’ onto the low back. For the latter, if the trunk does not stay stable, the hips lose the ability to powerfully push, and excessive mobility occurs at the trunk.

The Culprits
Hip-Flexor Tightness
Efficient running requires the hip extend to the level of the trunk. That is all. Yet, few of us–including runners–have that flexibility. Excessive sitting–the cornerstone of Western civilization–is likely the culprit, where our hips are stuck in a flexed position for hours at a time each day.

The hip-flexor muscles–the psoas, ilacus, and rectus femoris–all originate on the lumbar spine or pelvis, and insert onto the upper portion of the femur. They act to active flex the hip upward during running, but they also must passively relax to allow the thigh to extend. If the hip flexors become tight, any attempt to extend fully during the running gait will result in low back stress. Tight psoas muscles, especially, will pull on the lumbar spine–on which they’re connected–causing lumbar stiffness and possible low back pain.

Trunk-Stability Deficit
On the other end, the core-stability system must keep the trunk stable so that the hips have a strong base for push off. When the trunk–namely the lumbar spine and pelvis–fails to stay stable during the push off, excessive motion tends to occur. With each stride–180 per minute–the lumbar and pelvic joints are being stressed. This is a prime generator of low back pain and degenerative stress.

Low Back Pain During Running: Tips For Ultramarathon Runners Pt. 1Too Upright
If one has flexible hips and a strong core, it is still possible to have back pain. Since hip extension equal to the trunk is the prime job of the gluteal muscles, what happens if the trunk is completely upright?

Besides providing forward momentum, the vial importance of a hip-hinged forward trunk is that it gives the gluteals somewhere to go. A forward trunk creates a rearward, propulsive glute push off. But running too upright robs the hip extensors of a place to go. As a result, the body often compensates by extending through the lumbar spine.

This is extremely stressful to the low back, as the body is actively recruiting lumbar muscles to propel, which creates significant joint stress and overuse of a muscle group intended to stabilize and lightly rotate–not propel.

Excessive Trunk Rotation: ‘The Swivel’
A central component of a strong arm swing is the transfer of power from arms to the legs–and/or a counter-balance to the legs–using the trunk as a conduit. Inefficiency in the arm swing can cause a hyper-rotation, a ‘swivel-effect,’ where the arms twist from side to side, rather than pumping forward and back. This can cause the trunk to excessively rotate, often concentrating the motion in the lumbar spine.

Again, this left-and-right twist that propagates 180 times per minute creates a potentially enormous stress to the low back, often resulting joint wear and tear, and low back pain.


Source: www.irunfar.com; Joe Uhan; November 11, 2014.