Abstract: Provided herein are systems and methods that use a video content analysis algorithm to measure and quantify repetitive motion activity of a designated body part, including velocity, acceleration, frequency, and duty cycle, without applying sensors or other instrumentation to the body, for the purpose of preventing repetitive motion injuries. In some embodiments, the video-based direct exposure assessment system uses marker-less video and a video content analysis algorithm. The video content analysis algorithm is able to recognize and identify the pattern of repetitive motion, through a process known as cyclic motion analysis. Determination of the cycle pattern provides parameters for determining a body part's activity level, and thereby allows determination of the body part's activity level.