ORIGINAL PAPER Smart shirt system for compensatory movement retraining assistance: feasibility study Peteris Eizentals 1 & Alexei Katashev 1 & Alexander Oks 2 & Guna Semjonova 3 Received: 23 December 2019 /Accepted: 11 March 2020 # IUPESM and Springer-Verlag GmbH Germany, part of Springer Nature 2020 Abstract 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. Keywords Smart shirt system . Compensatory movements . Smart textile . Movement retraining 1 Introduction Body movements are complex tasks performed by the joint effort of the skeletomuscular and neural system of the body. Although there is no single correct way how to perform each movement, there is an optimal way of movement, which min- imizes and controls physiological stresses on joints involved in the movement. In the absence of normal movement pat- terns, compensatory or faulty movements can be used to achieve functional motor skills necessary for performing a task. Compensatory or faulty movement patterns can be caused by limited motion range due to injury or pathology, muscular imbalance and overuse or disuse of involved muscles. For maintaining the normal function, any movement limit at a joint must be compensated elsewhere in the system. These compensatory movements may result in increased stress and strain on moving joints and involved muscles and ligaments [1]. There is a growing amount of evidence linking compensatory movements to musculoskeletal pain and pathol- ogy [2–5]. Movement retraining is generally agreed to be the best practice for treating compensatory movements [ 6, 7]. Movement retraining exercises restore or establish a correct movement pattern by improving the muscle balance of the muscles involved in the movement or increasing the limited motion range. Special sets of exercises have been designed and are used by physiotherapists to test and treat the typical compensatory movement regions [8], however, movement retraining is a time-consuming task requiring numerous visits to the physiotherapist. Ideally, a patient should be able to perform exercises independently according to the guidelines of the physiotherapist, however, performing the exercises with only self-monitoring poses the risk of inefficient or even po- tentially harmful training in case the patient has misunder- stood the instructions. In addition, for some exercises self- monitoring is unsuitable or even impossible, and mirrored * Peteris Eizentals peteris.eizentals@gmail.com; peteris.eizentals@rtu.lv 1 Institute of Biomedical Engineering and Nanotechnology, Riga Technical University, Riga, Latvia 2 Institute of Design Technologies, Riga Technical University, Riga, Latvia 3 Faculty of Rehabilitation, Riga Stradins University, Riga, Latvia Health and Technology https://doi.org/10.1007/s12553-020-00420-x