(Unknown Author)

Pain in the Workplace

Work can cause pain. Any strong effort exerted over a long time usually causes some degree of pain, or at least discomfort. This is natural. Usually the tissues strengthen with mild overuse. This was first noted in bone by J.Wolff and reported in 1872. Now it is referred to as Wolff's Law. But we also know that too much overuse, e.g., repeatedly bending a bone, can cause stress fractures. The same is true of all tissues. Muscles and tendons become thicker and stronger with use, but if those same stresses that cause them to become stronger are applied to excess, the tissues break down, and now we have an injury. Such an injury is often called a repetitive strain injury (RSI) or cumulative trauma disorder (CTD).

How Much is Too Much?

No one really knows for sure. Guidelines are at this very moment being worked out....in the midst of great debate. But at least we can agree that certain conditions at work may present risk of injury to susceptible individuals. These are called "Risk Factors".

Unfavourable Working Conditions and Their Potential Effects. These health effects are based upon epidemiologic studies and the presence of the risk factor increases the risk of an individual developing a chronic work-related musculoskeletal injury. All potential health effects depend on the length of exposure to the conditions, the magnitude or size of the stressor, and the variation of the exposure.

Risk Factors Possible Tissue Changes Example Diagnoses

High Forces/Moments Strain in tendons or muscles. High forces for short duration may lead to tissue disruption. Moderate forces for long durations may lead to creep in tendons or muscle fatigue. Tendinitis
Muscle strain

Exertion of force in non-optimal postures Increased fatigue Muscle pain

Extreme Posture Compression of blood vessels or nerves Carpal Tunnel Syndrome

Overhead work Increased intramuscular pressure in supraspinatus with reduction in blood flow Myalgia of the trapezius and/or supraspinatus and supraspinatus tendinitis

Whole Body Vibration Increased shrinkage of intervertebral disks Low back pain

Hand/Arm Vibration Increased grip force to maintain control of object
Damage to nervous tissue
Increased fatigue and muscle pain
Carpal Tunnel Syndrome
Raynaud's Disease

Immobile Posture Static contraction of muscles Myalgia/Tension Neck syndrome

High Frequency Movements High velocity of tendon sliding combined with static contraction of more proximal muscles Tenosynovitis
Myalgia/Tension Neck syndrome

Risk Factors	Possible Tissue Changes	Example Diagnoses
High Forces/Moments	Strain in tendons or muscles. High forces for short duration may lead to tissue disruption. Moderate forces for long durations may lead to creep in tendons or muscle fatigue.	Tendinitis Muscle strain
Exertion of force in non-optimal postures	Increased fatigue	Muscle pain
Extreme Posture	Compression of blood vessels or nerves	Carpal Tunnel Syndrome
Overhead work	Increased intramuscular pressure in supraspinatus with reduction in blood flow	Myalgia of the trapezius and/or supraspinatus and supraspinatus tendinitis
Whole Body Vibration	Increased shrinkage of intervertebral disks	Low back pain
Hand/Arm Vibration	Increased grip force to maintain control of object Damage to nervous tissue	Increased fatigue and muscle pain Carpal Tunnel Syndrome Raynaud's Disease
Immobile Posture	Static contraction of muscles	Myalgia/Tension Neck syndrome
High Frequency Movements	High velocity of tendon sliding combined with static contraction of more proximal muscles	Tenosynovitis Myalgia/Tension Neck syndrome