Low back pain (LBP) is one of the most common musculoskeletal disorders in developed countries. Underactive gluteal muscles (i.e., weak, long and do not function correctly) are suggested to be a causative factor for LBP, and indeed there has been some hype surrounding training for the glutes recently. But, what does the evidence make of these claims?
What are the glutes?
The glutes, or gluteal muscles, are a group of three muscles that make up the buttock: gluteus maximus (largest), gluteus medius (middle) and gluteus minmis (smallest). These muscles originate from the ilium (rim of the pelvis) and sacrum (top part of tail bone) and they insert on the femur (thigh bone). They function to move the hip joint into extension (backwards), abduction (move away from midline), external rotation (rotate outwards) and internal rotation (rotate inwards).
Why are the glutes often weak?
When we run, the glutes hold our pelvis level and steady, extend our hip, propel us forward, and keep our legs, pelvis, and torso aligned. So, when our glutes are faulty, our entire kinetic chain (i.e., the effect joints and segments have on one another to perform human movement) gets disrupted. The issue is that glutes are not as active as other running muscles during routine activities, which can make your hamstrings, quadriceps, and calves disproportionately stronger. Another issue is that most strength-training routines do not isolate the glutes. If an exercise requires several muscles to perform the movement, the majority of the work will be done by the strongest of those muscles. Also, tight muscles, specifically the hip flexors, can inhibit the glutes and prevent their muscle fibres from firing.
The posterior chain is a group of muscles on the posterior of the body, which includes the gluteal muscles. The posterior chain is comprised of some of the largest muscles in the body, yet in the vast majority of individuals, they do not perform well. There are several reasons for this including biomechanical, behavioural and societal factors, but increased sedentary lifestyles are a major contributing factor.
Low back pain
LBP can be caused by several factors, although injuries to the muscles and joints are perhaps to most common types, and are of the least concerning when compared to more serious causes of LBP. These include strains, sprains and arthridities. So, it would be logical to assume that muscles that perform suboptimally may lead to episodes of LBP. But, what does the literature say about the effect of underactive glutes on LBP?
What’s the evidence?
Despite confident assertions by individuals within the healthcare profession about the effects of gluteal muscle function on LBP, there is limited, low- moderate-quality evidence in the scientific literature to support these purported claims.
Weakening of abdominals
Weakening of the abdominal muscles among the trunk muscles of LBP patients is generally prevalent, and the strengthening of the abdominal muscles is essential in recovery of the spinal neutral position (position in which the three normal spinal curves are centred to provide optimal biomechanical alignment). When imbalance between the abdominal muscles of the trunk and extensor muscles occurs, it triggers LBP and reduces stabilisation of the lumbar (low back) segment.
Hips role in LBP
The ability to actively control the muscles of the hip plays an important part in lumbar stability. As a function of the gluteus maximus muscle, the sacroiliac joint delivers loads from the trunk to the lower limb, and if this joint moves excessively, it results in pressure on the joints and discs between the L5–S1 vertebral body, sacroiliac joint, and pubic symphysis, which leads to functional failure of the sacroiliac joint and LBP.
Gluteal exercises and LBP
Studies on low back stabilisation exercises and isometric gluteal exercises in patients with LBP found the effect of exercises on reducing LBP was greater when compared to low back stabilisation alone. This suggests isometric gluteal exercises might help to reduced LBP.
Balance and gluteal function
Patients with LBP have a decreased balance ability compared with healthy people. When the body is exposed to an unexpected load, the muscles should swiftly respond to maintain balance and posture against the load. But, LBP patients have a delayed response time, triggering a problem in postural maintenance and balance.