The Science of Repetitive Strain Injuries
Repetitive strain injuries (RSI) develop when tissues are subjected to repeated low-level stress over extended periods, exceeding their capacity to recover between episodes of use. This creates a cycle of microtrauma and incomplete healing that gradually leads to tissue breakdown and sensitization of pain pathways. The pathophysiology involves multiple systems: musculoskeletal tissues experience microscopic damage from repetitive loading, while the nervous system becomes increasingly sensitive to normal stimuli. This process, called peripheral and central sensitization, means that activities which were once painless now trigger significant discomfort. Computer-related RSI typically affects the upper limbs through sustained postures combined with repetitive small movements. The muscles that stabilize your shoulder blade, neck, and forearm work continuously to maintain positions required for keyboard and mouse use, leading to fatigue and eventual breakdown of normal tissue architecture. Psychological factors play a significant role in RSI development and persistence. Work stress, time pressure, and fear of job security can increase muscle tension and delay recovery. The condition often becomes a complex interaction between physical tissue changes and psychological stress responses.
Contributing Factors
Modern computer work creates the perfect biomechanical storm for RSI development. Your shoulder blade muscles must work continuously to stabilize your arm in space while small intrinsic muscles perform thousands of precise finger movements each day.
Forward head posture, common during computer use, places your cervical spine in extension while loading the upper trapezius and levator scapulae muscles excessively. This altered posture changes the mechanics of your entire upper limb, affecting how forces are transmitted from your neck to your fingertips.
Static muscle contractions required for sustained postures reduce blood flow to working muscles, limiting oxygen and nutrient delivery while allowing waste products to accumulate. This metabolic stress contributes to muscle fatigue and the development of trigger points that can refer pain throughout the upper extremity.
The repetitive nature of typing and mouse use creates cumulative loading on tendons and ligaments that may exceed their adaptive capacity. Small movements repeated thousands of times can cause more tissue damage than larger movements performed less frequently, particularly when combined with poor posture and inadequate recovery time.