Thought Bytes...
March 2004

Repetitive Strain Injuries #5: Mechanical Stress

Pressure on tissues is mechanical stress. Resting your hands on the desk while typing is mechanical stress on the wrist (and potentially the median nerve). A lumbar support that is too low is mechanical stress on the sacroiliac joints. Sitting on a hard chair is mechanical stress on the sciatic nerve. Carrying a heavy purse is mechanical stress on the shoulder. Leaning on the edge of the desk is mechanical stress on the ulnar nerve. Basically, anything that could potentially cause a bruise is mechanical stress. When the skin is under mechanical stress, it causes a bruise because the blood vessels are damaged. At a deeper level mechanical stress causes friction on the tendon and tendon sheath. This irritation can lead to tendonitis and tenosynovitis respectively. Mechanical stress to the nerve slows the conduction of the signals to or from the nerve endings (either sensory or motor). Over time, mechanical stress to any tissues can cause inflammation and eventual scarring. Just look at your feet. The calluses on your feet are the result of mechanical stress to the skin. The skin’s natural defense is to add layers to protect the new skin underneath.

Avoiding mechanical stress can be as simple as rounding corners and padding surfaces. At the other extreme, reducing or eliminating mechanical stress may involve retraining workers or changing processes.

Home | Services | About ErgoSum | Contact