A novel method based on kinematical analysis is proposed to describe the three-dimensional motion of the ribs during breathing. The three-dimensional coordinates of markers on the ribs and vertebrae were used to calculate the orientation of the ribs as a function of time. A test measured the relative motion between the markers and the ribs using magnetic resonance and the results revealed that the skin motion artifact found for the ribs (absolute mean value 3.9 mm) would induce maximum errors of 4° on rib motion calculation. The method identified a signal coherent with the breathing cycle for the angles of the ribs around the mediolateral axis and was also able to show differences between healthy nonathletes and swimmers, which presented greater angular variation of the ribs (p < .05). In conclusion, this study has shown the reliability of using three-dimensional kinematic analysis to evaluate the movement of the ribs during breathing as well as its potential to identify differences in the behavior of the rib motion in trained swimmers and untrained healthy subjects.
Karine Jacon Sarro, Amanda Piaia Silvatti, Andrea Aliverti and Ricardo M. L. Barros
Gustavo Ramos Dalla Bernardina, Tony Monnet, Heber Teixeira Pinto, Ricardo Machado Leite de Barros, Pietro Cerveri and Amanda Piaia Silvatti
The aim of this study was to assess the precision and accuracy of an action sport camera (ASC) system (4 GoPro Hero3+ Black) by comparison with a commercial motion capture (MOCAP) system (4 ViconMX40). Both systems were calibrated using the MOCAP protocol and the 3-dimensional (3D) markers coordinates of a T-shaped tool were reconstructed, concurrently. The 3D precision was evaluated by the differences in the reconstructed position using a Bland–Altman test, while accuracy was assessed by a rigid bar test (Wilcoxon rank sum). To examine the accuracy of the action sport camera with respect to the knee flexion angles, a jump and gait task were also examined using 1 subject (Wilcoxon rank sum). The ASC system provided a maximum error of 2.47 mm, about 10 times higher than the MOCAP (0.21 mm). The reconstructed knee flexion angles were highly correlated (r 2 > .99) and showed no significant differences between systems (<2.5°; P > .05). As expected, the MOCAP obtained better 3D precision and accuracy. However, the authors show such differences have little practical effect on reconstructed 3D kinematics.