Movement retraining has proven to be a reliable way of treating compensatory movement faults, however, it is time-consuming and requires a lot of attention from a physiotherapist. Reliable movement retraining assistance system could enable patients to perform retraining exercises at home, thus increasing the possible exercise performance frequentness and consequently hasten the improvement. This paper describes a smart shirt system for movement retraining assistance. The smart shirt system is based on textile stretch sensors that are positioned over the typical movement fault sites for movement detection and monitoring. The information from the textile stretch sensors is used as visual feedback by the wearer for movement corrections. To verify the feasibility of the retraining assistance system, it was tested with a set of compensatory movement tests and retraining exercises. Each exercise was performed in a correct and incorrect manner, and the sensor measurement was analyzed to confirm the difference in measured signals between both cases. In total 11 exercises were performed to cover all of the typical compensatory movement sites, and for each retraining exercise, at least one sensor was identified, whose measurement could be used as feedback for the particular exercise.