Purpose: This work aimed to develop a novel indicator of upper limb manipulative movements. A principal component analysis (PCA) algorithm was applied to kinematic measurements of movements of the upper limbs performed during an everyday activity. Methods: Kinematics of the upper limb while drinking from a mug were investigated using the commercially available Xsens MVN BIOMECH inertial sensor-based motion capture system. The study group consisted of 20 male patients who had previously suffered an ischaemic stroke, whilst the reference group consisted of 16 males with no disorders of their motor organs. Based on kinematic data obtained, a set of 30 temporal and kinematic parameters were defined. From this, 16 parameters were selected for the determination of a novel indicator, the Upper Body Index (UBI), which served the purpose of assessing manipulative movements of upper limbs. Selection of the 16 parameters considered the percentage distribution of the parameters beyond the standard, the differences in mean values between the reference group and the study group, and parameter variability. Results: Analysis of kinematics allowed for the identification and selection of the parameters used in the development of the new index. This included 2 temporal parameters and 14 kinematic parameters, with the minimum and maximum angles of the upper limb joints, motion ranges in the joints, and parameters connected with movement of the spine recorded. These parameters were used to assess motion in the shoulder and elbow joints, in all possible planes, as well as spine movement. The values of the UBI indicator were as follows: in the case of the reference group: 13.67 ± 2.40 for the dominant limb, 13.71 ± 3.36 for the non-dominant limb; in the case of the stroke patient group: 130.86 ± 75.07 for the dominant limb, 155.58 ± 170.76 for the non-dominant limb. Conclusions: The developed UBI made it possible to discover deviations from the standard performance of upper limb movements. Therefore, the index may be applicable to the analysis of any sequence of movements carried out by the upper limb.
