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Microtrauma can include the microtearing of muscle fibres, the sheath around the muscle and the connective tissue. It can also include stress to the tendons, and to the bones (see Wolff's law). It is unknown whether or not the ligaments adapt like this. Increased lubrication in response to microtrauma to the bowels is a key factor to the beneficial effects of dietary fibre in increasing bowel robustness, though this is dissimilar to muscular hypertrophy. Microtrauma to the skin (compression, impact, abrasion) can also cause increases in a skin's thickness, as seen from the calluses formed from running barefoot. This might be due to increased skin cell replication at sites under stress where cells rapidly slough off or undergo compression or abrasion.
Most microtrauma cause a low level of inflammation that cannot be seen or felt. These injuries can arise in muscle, ligament, vertebrae, and discs, either singly or in combination. Repetitive microtrauma which are not allowed time to heal can result in the development of more serious conditions.
Back pain can develop gradually as a result of microtrauma brought about by repetitive activity over time. Because of the slow and progressive onset of this internal injury, the condition is often ignored until the symptoms become acute, often resulting in disabling injury. Acute back injuries can arise from stressful lifting techniques done without adequate recovery, especially when experimenting with more ballistic work, or work where the extensor spinae are stressed during spinal flexion when much of the load is commonly taken up by the slower to heal ligaments which may not adapt progressively to the stress. While the acute injury may seem to be caused by a single well-defined incident, it may have been preventable or lessened if not for the years of injury to the musculoskeletal support mechanism by repetitive microtrauma.
After microtrauma from stress (lifting weights) to muscles, they can be rebuilt and overcompensate to reduce the likeliness of re-injury. That is why progressive overload is essential to building muscle through working out.