This paper explores the design of a dynamically weighted therapy bar, which can provide real-time quantitative performance information and adjustments during rehabilitation exercise. In contrast, typical therapy equipment is passive, offering no feedback to the patient or clinician. The dynamic weighted bar (DWB) was designed and fabricated containing an inertial sensor which tracks the orientation of the bar and adjusts the position of an internal weight accordingly, in turn providing a targeted force imbalance between the patient's two arms. Step input experiments were performed on the device while it was held in various stationary positions. The DWB was able to successfully function and transmit motion information. It was able to produce a center of mass shift of 101.6 mm, and a complete travel time between 0.96 s and 1.41 s over the entire length. The use of the DWB device can offer many benefits during rehabilitation including access to more quantitative information for clinicians as well as the potential for more personalized therapy programs.