Low back pain is endemic in western industrialised countries with a lifetime prevalence exceeding 80%. What is true for the general population also counts for footballers. During one year around 36 % of footballers of different age groups and playing levels complain about an episode of low back pain.5 A genetic predisposition, injuries and muscular imbalances contribute to these numbers. Whereas injuries are rare (8-15.7 % of all injuries), muscular imbalances play a major role. Usually the muscles of the lower extremities are well trained whereas the back muscles as well as the important anterior-lateral abdominal muscle groups are often neglected. Most of the players also show a functional shortening of the psoas muscle. Week abdominal muscles and a short psoas muscle lead to a forward rotation of the pelvis and a consecutive hyperlordosis. This hyperlordosis can be accentuated further when kicking a ball, which in turn exerts a significant stress to the posterior structures such as the facet joints and the posterior part of the disc.
From a biomechanical point of view, the lumbar spine significantly contributes to the stabilisation as well as the flexibility of the trunk. Flexion/extension with a range of motion (ROM) of 70-80° and lateral bending (40-50°) are the main movements which have to be controlled by the active (muscles) and passive (ligaments, joints, discs) systems. Due to the orientation of the facet joints in a more sagittal plane, rotation movements are very limited which also protects the disc from shear forces.
During frequent and abrupt changes in direction, explosive acceleration and abrupt deceleration (which are typical for football), the lumbar spine has to tolerate and control extreme torsional, rotational and translational forces. Even with good muscular performance, there is still a considerable stress on the passive stabilisers such as the discs and the facet joints.6,7
With forceful stop and rotation movements, the compression forces on the lumbar disc can reach > 8600N which is > 60% of the maximum which can be tolerated by a healthy disc. Sagittal shear forces can reach up to 3300N which actually is supra-maximal.7