Assessment of three-dimensional joint kinematics of the upper limb during simulated swimming using wearable inertial-magnetic measurement units

Abstract

The analysis of the joint kinematics during swimming plays a fundamental role both in sports conditioning and in clinical contexts. Contrary to the traditional video analysis, wearable inertial-magnetic measurements units (IMMUs) allow to analyse both the underwater and aerial phases of the swimming stroke over the whole length of the swimming pool. Furthermore, the rapid calibration and short data processing required by IMMUs provide coaches and athletes with an immediate feedback on swimming kinematics during training. This study aimed to develop a protocol to assess the three-dimensional kinematics of the upper limbs during swimming using IMMUs. Kinematics were evaluated during simulated dry-land swimming trials performed in the laboratory by eight swimmers. A stereo-photogrammetric system was used as the gold standard. The results showed high coefficient of multiple correlation (CMC) values, with median (first-third quartile) of 0.97 (0.93-0.95) and 0.99 (0.97-0.99) for simulated front-crawl and breaststroke, respectively. Furthermore, the joint angles were estimated with an accuracy increasing from distal to proximal joints, with wrist indices showing median CMC values always higher than 0.90. The present findings represent an important step towards the practical use of technology based on IMMUs for the kinematic analysis of swimming in applied contexts.

The Use of IMMUs in a Water Environment: Instrument Validation and Application of 3D Multi-Body Kinematic Analysis in Medicine and Sport

“…The protocol proposed by Cutti et al [51] and slightly adapted to the sport context by Fantozzi et al [33] was used for estimating upper limb kinematics using IMMUs. Specifically, each upper limb is modeled as an open kinematic chain consisting of 4 rigid segments (thorax, upper-arm, forearm, and hand) with 7 degrees of freedom.…”

“…While the first calibration established mainly the joint angle offsets of the shoulder and the wrist, the second and third calibrations allowed for the orientation estimation of the mean flexion-extension and prono-supination axes of the elbow. Further details of the protocol can be found in Fantozzi et al [33]. …”

“…The segmentation of the simulated swimming stroke cycles was then performed to develop a semi-automatic algorithm that recognized the maxima of the elbow flexion-extension angle and the minima of the shoulder flexion-extension angle of the front-crawl [33]. The detection of the front-crawl temporal phases was performed using the algorithm proposed by Dadashi et al [52] which is based on a Kalman adaptive filtering of inertial signals recorded from sensors positioned on both the forearms and on the sacrum.…”

“…Successively, several studies have analyzed the temporal stroke parameters and the speed profile using single or multiple sensors, in one case also integrated with video [31]. However, the extraction of only spatiotemporal parameters is not sufficient to highlight differences between patients/athletes’ biomechanics, and a 3D multi-body kinematics analysis is required to better quantify their motor patterns and to improve the outcome of their therapy/performance [32,33]. …”

Behavioral Dynamics in Swimming: The Appropriate Use of Inertial Measurement Units

“…The complete explanation of the correction process was presented by Favre et al (2009). Moreover, this strategy can be used in water by calibrating in dry-land conditions before starting the aquatic tests, as described by Fantozzi et al (2016) in simulated swimming (i.e., legs constrained and upper limbs moving in the air). The results showed good agreement between the joint angles computed with the IMUs and the gold standard (coefficients of multiple correlations near 1).…”