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Front. Physiol. | doi: 10.3389/fphys.2018.00141

Player Monitoring in Indoor Team Sports: Concurrent Validity of Inertial Measurement Units to Quantify Average and Peak Acceleration Values

  • 1Department for Sports and Sport Science, Albert Ludwigs Universität Freiburg, Germany
  • 2Applied Public Health, Furtwangen University, Germany

The increasing interest in assessing physical demands in team sports has led to the development of multiple sports related monitoring systems. Due to technical limitations, these systems primarily could be applied to outdoor sports, whereas an equivalent indoor locomotion analysis is not established yet. Technological development of inertial measurement units (IMU) broadens the possibilities for player monitoring and enables the quantification of locomotor movements in indoor environments. The aim of the current study was to validate an IMU measuring by determining average and peak human acceleration under indoor conditions in team sport specific movements. Data of a single wearable tracking device including an IMU (Optimeye S5, Catapult Sports, Melbourne, Australia) were compared to the results of a 3D motion analysis (MA) system (Vicon Motion Systems, Oxford, UK) during selected standardized movement simulations in an indoor laboratory (n=56). A low-pass filtering method for gravity correction (LF) and two sensor fusion algorithms for orientation estimation (Complementary Filter (CF), Kalman-Filter (KF)) were implemented and compared with MA system data. Significant differences (p < 0.05) were found between LF and MA data but not between sensor fusion algorithms and MA. Higher precision and lower relative errors were found for CF (RMSE = 0.05; CV = 2.6%) and KF (RMSE = 0.15; CV = 3.8%) both compared to the LF method (RMSE = 1.14; CV = 47.6%) regarding the magnitude of the resulting vector and strongly emphasize the implementation of orientation estimation to accurately describe human acceleration. Comparing both sensor fusion algorithms, CF revealed slightly lower errors than KF and additionally provided valuable information about positive and negative acceleration values in all three movement planes with moderate to good validity (CV = 3.9 – 17.8%) . Compared to x- and y-axis superior results were found for the z-axis. These findings demonstrate that IMU-based wearable tracking devices can successfully be applied for athlete monitoring in indoor team sports and provide potential to accurately quantify accelerations and decelerations in all three orthogonal axes with acceptable validity. An increase in accuracy taking magnetometers in account should be specifically pursued by future research.

Keywords: locomotion analysis, Orientation estimation, Inertial measurement unit, Complementary filter, Physical demands, Indoor team sports

Received: 09 Nov 2017; Accepted: 12 Feb 2018.

Edited by:

Kamiar Aminian, École Polytechnique Fédérale de Lausanne, Switzerland

Reviewed by:

Antonio Dello Iacono, Zinman College for Physical Education and Sport, Israel
Filipe M. Clemente, Polytechnic Institute of Viana do Castelo, Portugal  

Copyright: © 2018 Roell, Roecker, Gehring, Mahler and Gollhofer. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Ms. Mareike Roell, Albert Ludwigs Universität Freiburg, Department for Sports and Sport Science, Freiburg, Germany, mareike.roell@sport.uni-freiburg.de