Lower-back pain that radiates into the leg is one of the most unpleasant problems for a person who trains. Often behind it lies an intervertebral disc herniation. At the same time, a disc is not a "fragile part" that breaks from a single wrong movement: a herniation develops as a result of a combination of load, genetics, age and lifestyle. The editorial team explains how this works and where pharmacology fits in here.
What an intervertebral disc herniation is
An intervertebral disc consists of two parts. In the centre is the gelatinous nucleus pulposus, rich in water and proteoglycans, and at the periphery is the annulus fibrosus of several layers of dense collagen fibres. Together they work as a shock absorber and at the same time provide mobility of the spine.
A herniation is the displacement of disc material, predominantly the nucleus pulposus, beyond its normal boundaries through cracks in the annulus fibrosus. Most often this occurs in the lumbar region at the L4–L5 and L5–S1 levels, which bear the greatest load, and also in the cervical region.
A herniation on its own may not cause symptoms. Pain arises when it irritates or compresses a nerve root, and also through the chemical inflammation caused by nucleus material. The typical manifestation is radicular pain radiating into the leg (sciatica), sometimes with numbness or weakness.
Radiologists distinguish several forms of disc displacement depending on its shape and degree. These terms often appear in MRI reports and frighten patients, although on their own they do not determine the severity of symptoms.
| Term | What it means |
|---|---|
| Protrusion | Displacement with a broad base, the annulus fibrosus partly preserved |
| Extrusion | Disc material comes out further, the base narrower than the released fragment |
| Sequestration | A fragment loses its connection with the disc and lies freely in the canal |
| Disc degeneration | Loss of water, reduction of disc height, cracks in the annulus |
How load damages a disc
Classic measurements of intradiscal pressure, begun by A. Nachemson in the 1960s and refined later by H.-J. Wilke and co-authors, showed that pressure in a disc depends on the position of the body: lowest when lying down, higher when standing and sitting with a forward lean, and highest when lifting weight with a bent back (Nachemson, 1966; Wilke et al., 1999).
Laboratory studies on animal spinal segments showed that repeated flexion and extension under compression can cause a gradual advance of the nucleus through the annulus fibrosus and form a herniation (Callaghan & McGill, 2001). That is, a herniation is more often the result of an accumulation of micro-damage than of a single "unfortunate" lift.
A dangerous combination is considered to be flexion and twisting of the spine under load, especially when the muscles are tired and technique deteriorates. The morning hours are also risky: after a night's sleep the discs are saturated with water, and their stiffness during flexion is higher.
At the same time, moderate regular load is beneficial for discs: nutrition of a disc occurs through diffusion, which is aided by movement. That is why both a sedentary lifestyle and chaotic excessive loads are equally not to the benefit of the spine.
Sports and risk groups
Loads on the lumbar region are especially high in weightlifting, powerlifting, CrossFit, rowing, gymnastics, wrestling, and also in sports with twisting — golf, tennis, throwing. In these disciplines axial compression, flexion and rotation are combined.
However, the sport is only part of the picture. Twin studies have shown that a significant part of the variability in disc degeneration is explained by heredity, not by physical load alone (Battie et al., 2009). That is why two people with the same training programme may have completely different states of their discs.
Age also matters: over the years a disc loses water, and the annulus fibrosus becomes less elastic. Symptomatic lumbar herniation most often occurs in people of working age, roughly from 30 to 50 years.
Other risk factors include excess body weight, smoking, prolonged sitting, vibration (for example, in drivers), and also previous episodes of back pain.
- repeated flexion and twisting under load;
- heavy lifts under fatigue and with deteriorating technique;
- a hereditary predisposition to disc degeneration;
- age, excess weight, smoking, prolonged sitting.
Pharmacology and lifestyle
There is little direct evidence that some drug causes a disc herniation, but several indirect mechanisms deserve attention. Anabolic steroids quickly increase strength and body mass, allowing one to work with weights to which the passive structures of the spine — discs, ligaments, joints — have not yet adapted. The Endocrine Society describes a wide spectrum of risks of such substances, and the mismatch between muscle strength and connective-tissue strength is one of them (Pope et al., 2014).
Painkillers and non-steroidal anti-inflammatory drugs, which athletes take "prophylactically", can mask early signals — lower-back pain, stiffness — and allow one to continue training with a load that is already causing harm.
Prolonged systemic use of corticosteroids reduces the density of bone tissue and increases the risk of compression fractures of the vertebrae. This is not a herniation, but back pain against a background of such therapy requires a doctor's separate attention.
Smoking is linked to impaired disc nutrition through the narrowing of small blood vessels. Excess body weight, in particular gained quickly during a "mass-gaining" phase, increases the constant load on the lumbar region.
A herniation on MRI does not yet mean pain
One of the most important discoveries of recent decades: disc changes on MRI are very common in people who have no back pain. A systematic review showed that the frequency of protrusions and signs of degeneration in asymptomatic people increases with age and, already in middle age, concerns a significant proportion of those examined (Brinjikji et al., 2015).
This means that finding a herniation on an image does not always explain pain, and its absence does not rule out other causes. The doctor compares MRI data with the clinical picture: the location of the pain, neurological symptoms, examination findings.
Another encouraging circumstance is that a significant part of herniations decrease or resolve over time, especially large extrusions and sequestra, which more strongly provoke an immune reaction. That is why, for most patients without a neurological deficit, treatment begins with conservative measures.
For an athlete the practical conclusion is this: one should not panic over an MRI report, and still less refuse movement. It is far more important to understand which loads provoke symptoms and to gradually restore tolerance to them.
Editorial conclusions
An intervertebral disc herniation is most often the result of an accumulation of micro-damage to the annulus fibrosus due to repeated flexion and twisting under load, against a background of a genetic predisposition and age-related changes.
Anabolic steroids, painkillers and rapid mass gain indirectly increase the risk by allowing unadapted structures of the spine to be overloaded.
Disc changes on MRI often occur even without pain, and most symptomatic herniations are successfully treated conservatively.
We also recommend reading our materials on the prevention and diagnosis of disc herniation, on safe technique in basic exercises and on tendinitis in athletes.
References
- Nachemson A. The load on lumbar disks in different positions of the body. Clin Orthop Relat Res. 1966;45:107–122.
- Wilke HJ, Neef P, Caimi M, et al. New in vivo measurements of pressures in the intervertebral disc in daily life. Spine. 1999;24(8):755–762.
- Callaghan JP, McGill SM. Intervertebral disc herniation: studies on a porcine model exposed to highly repetitive flexion/extension motion with compressive force. Clin Biomech. 2001;16(1):28–37.
- Battié MC, Videman T, Kaprio J, et al. The Twin Spine Study: contributions to a changing view of disc degeneration. Spine J. 2009;9(1):47–59.
- Brinjikji W, Luetmer PH, Comstock B, et al. Systematic literature review of imaging features of spinal degeneration in asymptomatic populations. AJNR Am J Neuroradiol. 2015;36(4):811–816.
- Pope HG Jr, Wood RI, Rogol A, et al. Adverse health consequences of performance-enhancing drugs: an Endocrine Society scientific statement. Endocr Rev. 2014;35(3):341–375.
Andriy Melnyk
A strength-sports coach and author of programs for beginner and intermediate levels. Writes about training planning.
