Crew exercise is important for maintaining the health and fitness of astronauts, and to prevent adverse health problems, such as bone density losses. We developed algorithms for ESPRIT: an Exercise Sensing and Pose Recovery Inference Tool, in support of NASA's Exercise Countermeasure Program. ESPRIT is a stereo camera system that monitors exercise activities, detects markers placed on the body and other image features and recovers 3D kinematic body pose. ESPRIT relies on strong prior knowledge and modeling of human body, pose, dynamics, and appearance. It also relies on advanced statistical inference techniques to achieve robust and accurate motion capture. Phase I result has been promising and has demonstrated motion capture of several exercises, including walking, curling and dead lifting. Phase II effort will focus on enhancement of algorithms, development of an ESPRIT prototype, detailed performance evaluation, and delivery of prototype for testing and demonstration.