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You've heard it called Repetitive Strain Injury (RSI) and CarpalTunnel Syndrome. It is also known as: Tendinitis, Tennis Elbow or Epicondylitis,DeQuervain's Disease, and Thoracic Outlet Syndrome. Itcauses pain and discomfort in the neck, shoulders, wrists, forearms, fingers, elbows, andback. It can be disabling. However, it is preventable.

Cumulative Trauma Disorder (CTD) is a wear-and-tear injury to the softmuscle tissue. It is caused by continual stress to specific tendons, joints, or muscles.Stress is induced by repetition, force, vibration, and cold. Your body isstressed by daily living activities such as: turning a door knob, housecleaning, opening a jar, graspinga cup, driving a car, reading, and writing, as well as recreational activities such as: painting, home improvement, bike riding, racquet sports, golf, playing musical instruments, craftwork, computer games, gardening and cooking. If yourbody is not able to recover from these stressful activities, it will no longer toleratethem.


Awkward postures take the body out of neutral positions and can result in increased stress to muscles, tendons, and nerves. For example, the neutral position for the wrist is when the wrist is straight. Working with the wrist in a forward bent position results in compression or crimping of tendons on the palm side of the wrist and tension of tendons on the back of the wrist. This awkward position restricts the normal ability of the tendons to glide during the work activity and may result in injury. Awkward positions also increase muscle load, constrict blood flow, and in some cases compress nerves.

High Repetition can result in injury if the repetition exceeds the body's capacity to recover from the muscle tension that results from repetitive movement. Typically, given time, muscles, tendons, and ligaments accommodate to given levels of repetition. Problems arise when there are dramatic increases in repetition and no action is taken to change how a task is done. Symptoms of repetitive strain (such as muscle tension, aches and pains that come and go, burning or tingling and numbness) are a signal that you may be exceeding your limits.

Forces vary with equipment type, design, and state of repair. Recognize that when applying force to an object, forces are transferred through your body. For example, when activating a pipette, forces are transferred to your finger or thumb. Forces transferred to your body are affected not only by the amount of force, but also the distance through which a force is applied. Consider how your arms, neck and back feel when the vortex machine is at the back of the bench.

Choosing equipment that requires less force to activate and requires a shorter activation distance can reduce forces transferred to your body. Assuring equipment is in good working order also helps reduce the overall forces to the body.

The amount of force your body can accept without injury varies with the individual. It is also dependent on the size of the joint and the size of ligaments and muscles surrounding the joint. In general, it is best to position yourself and/or use tools that help transfer forces to larger joints (e.g., using the larger shoulder muscle instead of the smaller wrist).

Contact Stresses occur when a force is concentrated to a small area, also known as pressure. Contact stress occurs when resting your forearm against the sharp edge of a hood. In this case, highly concentrated forces can disrupt the ability of the tendons to move within the forearm and cause inflammation of the tendon. If resting on a sharp edge is necessary, either pad the edge or pad yourself to distribute forces. When grasping hand-held equipment, contact stress occurs in the hand and this stress can effect structures of the hand. It is important to assure hand-held equipment fits your hand well. Hand-held equipment should not result in pressure at the base of the palm of the hand since the pressure can effect the median nerve. If necessary, padding can be added to the equipment or you can wear a padded glove to reduce pressure.


Vibrations can be transferred to the body when holding an object on some type of oscillating equipment. For example, vibration to the hand occurs when holding tubes by hand onto a vortex mixer or impact driver. Vibration can be eliminated by using a vortex mixer rack instead of holding the tubes by hand. In the case of the impact driver where it is not possible to eliminate vibration, the amount of vibration transferred to the body can be reduced by padding the hand.

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