Studies suggest that low back pain is associated with repeated forward bending and lifting objects. Bending and lifting weight may cause back pain and makes the patient more prone to get slip disc issues.
Nachemson found that holding a 20 kg load while bending forward only 20 degrees increased the lumbar IVD load by over 200 percent. Glute max(GM) is functionally coupled with back extensor muscles while lifting the weight from full flexion.
GM has played a crucial part in bipedalism in humans, which allows upper extremities to be used during functional activities, which are unavailable for quadrupeds.
GM also has proximal attachments with lumbar bone structures, ligaments and thoracolumbar fascia which helps to transfer load between the pelvis and lower back during flexion-extension.GM is tightly coupled with lumbar para-spinal muscles via thoracolumbar fascia. And biceps femoris is coupled via sacrotuberous ligament.
If GM is inhibited Lumbo-pelvic rhythm is disturbed during sagittal plane movement.
Ville Leinonen and colleagues found that, During initial sagittal flexion movement of the trunk , erectorspinae (ER) and biceps femoris were activated simultaneously and GM was activated last. During later part of the trunk flexion, the erector spinae activity ended first then gradually GM and biceps femoris acivity , But in patients with pain, during beginning of the flexion GM fired significantly later than ES and during end of flexion got deactivated earlier (simultaneously with ES). In short GM activation duration was significantly reduced in back pain patients.
During initial sagittal extension of trunk biceps got activated first then gradually GM, ES and during end of the extension biceps relaxed first then gradually GM & ES. But in patients with back pain, GM got relaxed simultaneously with biceps. This also shows that GM activity was reduced during extension.
Amy H. Amabile and colleagues found that patients with chronic LBA had atrophy of GM muscle. Both the above studies show that activity of GM reduces with chronic law back pain patients.
Clinical implementation :
People with lower back pain who have to bend forward in daily routine and also they have to lift objects in saggital plane should be considered for GM strengthening during their rehabilitation rather focusing on other group of muscles. FOR EXERCISE PRESCRIPTION READ : GLUTEUS AMNESIA
- Back and Hip Extensor Activities During Trunk Flexion/Extension: Effects of Low Back Pain and Rehabilitation Ville Leinonen, BM, Markku Kankaanpa¨a¨, MD, Olavi Airaksinen, DMSc, Osmo Ha¨nninen, DMSc, PhD
- Atrophy of gluteus maximus among women with a history of chronic low back pain Amy H. Amabile ,John H. Bolte,Saskia D. Richter
- Image coutsey: charterphysio.co.uk