Not all injuries occur in a single instant.  Cumulative Trauma is an injury that occurs over the course of time.  These are injuries to the musculoskeletal and/or nervous systems that may be caused by repetitive tasks, forceful exertions, vibrations, mechanical compressions (i.e. pressing against hard surfaces) or sustained or awkward positions. 

These injuries can sometimes be crippling and can develop gradually over periods of weeks, months, or even years. 

Examples include carpal tunnel and other arm/wrist/hand injuries, tendonitis, lower back disorders, cervical radiculopathy, and thoracic outlet syndrome.