ABSTRACT

Injuries associated with manual tasks can be acute, that is, they can occur as a consequence of a single exposure to a high force. Acute injuries occur when the load on a body tissue (e.g., muscle, tendon, ligament, bone) is greater than the tissue can withstand. Cumulative injuries, on the other hand, are those which arise as a consequence of repeated or long duration exposure to lower levels of force. Even low levels of load can cause small amounts of damage to body tissues. This damage is normally repaired before injury occurs. However, if the rate of damage is greater than the rate at which repair can occur, then an injury may result. Injuries can also result from a combination of these mechanisms, for example, a tissue which has been weakened by cumulative damage may be vulnerable to acute injury by lower forces. Manual task risk assessment needs to consider these possible mechanisms.