Patient Education: Anatomy and Physiology

Sub-acute low back pain (LBP) is a prevalent musculoskeletal issue among active military personnel, often affecting performance, readiness, and quality of life. Defined as pain persisting between 1–3 months, sub-acute LBP represents a critical stage between acute onset and chronic persistence. Understanding the anatomy and physiology involved is essential to addressing this condition effectively within the military context.

The lower back, or lumbar spine, consists of five vertebrae (L1–L5), intervertebral discs, facet joints, ligaments, muscles, and neural structures. These components work in harmony to provide stability, flexibility, and support for upright posture and movement. The vertebrae are separated by intervertebral discs composed of a tough outer annulus fibrosus and a gelatinous inner nucleus pulposus, which serve as shock absorbers and allow spinal motion. Surrounding muscles, including the multifidus, erector spinae, quadratus lumborum, and abdominal musculature, are critical in stabilizing and moving the spine during activity.

In active military members, the high physical demands of training, deployment, and combat readiness contribute significantly to the development of sub-acute LBP. Repetitive heavy lifting, prolonged load carriage, jumping, and rapid directional changes place intense mechanical stress on the lumbar spine. Additionally, wearing heavy gear and operating in austere environments exacerbates the risk of muscle fatigue, joint irritation, disc degeneration, and microtrauma.

The physiological response to low back pain typically begins with localized inflammation, muscle guarding, and altered neuromuscular activation. In the sub-acute phase, inflammatory markers may persist, though to a lesser extent than in acute injury. This can lead to reduced flexibility, weakened core musculature, and impaired proprioception. In military populations, these physiological changes are often compounded by insufficient rest periods and a drive to return to duty quickly, sometimes before full recovery.

Moreover, psychosocial factors such as stress, sleep deprivation, and mental health challenges can amplify the perception of pain and slow recovery. These factors are common in the military and may contribute to maladaptive pain behaviors or fear-avoidance patterns, which increase the risk of chronicity.

Management of sub-acute LBP in military members should focus on restoring function, preventing chronic progression, and maintaining operational readiness. A multidisciplinary approach is often warranted, including massage therapy and physical therapy to improve flexibility, strength, and motor control; ergonomic training for load management; and behavioral strategies to address psychosocial influences.

Emphasis should also be placed on education to counteract common misconceptions about pain and encourage gradual return to activity. Pain misconceptions are particularly impactful in military settings. These misconceptions include the following:

Misconception 1: Pain is a normal part of aging or service.
Active service members are often exposed to intense physical activity, repetitive strain, and high-risk environments. The belief that pain is just a normal part of service can prevent early treatment and worsen long-term outcomes. Many service members assume pain is just part of the job, but pain shouldn’t be ignored. Pain often signals an issue that needs to be treated and “pushing through” can lead to more serious pathology.

Misconception 2: Pain always means damage.
In reality, pain is a complex experience created by the nervous system, and it doesn’t always correlate with tissue damage. Conditions like fibromyalgia or neuropathic pain demonstrate that people can experience intense pain even when there is no clear physical cause. A better understanding of this concept can reduce fear avoidant behaviors and encourage more successful recovery practices.

Misconception 3: Pain is “all in your head.”
While the brain does process pain signals, this doesn't mean the pain is imagined or not real. Pain is a genuine and deeply personal experience influenced by a range of factors, including stress, past trauma, mood, and context. The belief that pain is “all in your head” can prevent people from seeking help, even though pain is a real and complex experience.

Misconception 4: Medication is the only way to address pain.
Relying only on medication, especially opioids, can be a risky strategy. A well-rounded multidisciplinary approach (e.g. physical therapy, massage therapy, exercise, and mental health support) is often safer and more effective for long-term performance & recovery.

In conclusion, sub-acute low back pain in active military personnel is a complex condition influenced by the unique biomechanical and psychosocial demands of service. Anatomical structures such as the vertebrae, discs, and surrounding musculature play central roles in the development of pain, while physiological responses during this stage reflect both tissue healing and neuromuscular dysfunction. Addressing sub-acute LBP with a comprehensive, individualized approach is essential to ensure recovery, prevent chronic issues, and sustain military readiness.