ntroduction Various methods of rehabilitation are used at present; among which Kinetic Control is constituting as one of the concepts and according to which it is important to test the patients during functional training in order to determine their preferred direction of motion and weak links in the kinetic chain. Functional training takes into consideration the direction of motion, motor work of muscle units and endurance of dysfunctional muscle groups. Aim To choose tests which will determine muscular imbalances on the basis of Kinetic Control and to determine how the sitting position and stability of the lower limb improve functionally. Case study The study presents a 43-year-old patient with history of left knee joint injury in 2001. In 2006, the patient suffered from severe sciatic neuritis radiating to the left lower limb. The rehabilitation programme which lasted for a year included rehabilitation of the lumbar spine. Results and discussion Prior to the therapy, the patient was examined according to the concept of Kinetic Control, i.e. tests were performed in order to determine the direction of motion as well as muscular imbalances. After the training period, the tests showed functional improvements of the sitting position and the stability of the left lower limb when performing everyday motor activities. Conclusions 1. The performed tests, which were part of functional training, showed abnormalities in the direction of motion and muscular imbalances. 2. An improvement occurred in the sitting position and in the stability of the left lower limb.