Considering that nothing ever operates in isolation, it makes sense that we, the practitioners, have been assessing not just the site of the pain, but above and below as well for a more holistic approach. This is where the idea behind glute weakness comes in.
Biomechanically speaking, the musculature of the lumbar spine is designed to extend and laterally flex. I would also argue the primary function of the glutes is not to move but to stabilise the pelvis. However, when there is a lack of stability at any joint, we see the surrounding muscles increase in tonicity to compensate and avoid issues caused by instability (5).
With LBP, this manifests as a lack of pelvic stabilisation (aka poor glute function or weakness) in which the muscles of the lumbar spine take over as the primary stabilisers due to their insertions onto the superior aspect of the ilium (top of the pelvis). Therefore, when the low back musculature attempts to stabilise the pelvis (which is not its primary function), additional muscle fiber recruitment is required. This can increase muscle tension, tenderness and may contribute to pain; or so the thought process goes (1)(3).
There’s also the potential for excessive recruitment of the lumbar spine musculature with movements where spinal extension replaces true hip extension. Take a rounded spine in squats or an inability to hinge effectively through movements for example. This shifts forces into the low back and moves them away from the glutes, resulting in strengthening of the spinal extensors and diminishing the strength gains in the hip extensors (gluteals).