Date Published: June 6, 2019
Publisher: Public Library of Science
Author(s): Thomas Rietveld, Riemer J. K. Vegter, Rienk M. A. van der Slikke, Aldo E. Hoekstra, Lucas H. V. van der Woude, Sonja de Groot, Yih-Kuen Jan.
The purpose of the current study was to assess the inter-trial reliability and construct validity (talented juniors vs. international adult players) of four wheelchair tennis field tests using inertial measurement units (IMUs). Twenty-one elite wheelchair tennis players completed four tests, which evaluate the sprinting and manoeuvrability abilities in wheelchair tennis. During all tests 3 IMUs were attached to both wheels and the frame of the athlete’s wheelchair. The IMUs enabled analysis of individual test dynamic characteristics, i.e. the linear/rotational velocity and acceleration data, as well as detected pushes. All tests showed high ICCs (0.95–0.99) for the inter-trial reliability for the IMU-based end times and also the construct validity was good, i.e. talented juniors could be discriminated from international adults. Also, velocities and accelerations during the tests could be consistently visualized, meaning that differences in test performance among participants could be designated. Within the experimental context, the field tests could be regarded as reliable and valid. With the use of IMUs it is possible to verify more detailed performance characteristics, visualize the test execution, as well as differentiate between a talented junior and international adult group and within individuals over time.
Wheelchair tennis became part of the Paralympic Games in 1992 and has grown in interest ever since . In 2016 participants from over 100 countries participated in wheelchair tennis at varying levels and as such it is one of the fastest growing sports for people with a disability . The rules in wheelchair tennis are similar to the able-bodied variant, except that with each tennis stroke an additional ball bounce is permitted. One of the main differences between wheelchair tennis and able-bodied tennis is the wheelchair, which provides an extra set of constraints onto the athlete .
The descriptive statistics of all participants are shown in Table 3. For one participant of the adult group the data of the Spider test was lost due to an empty battery of the IMU. Scores on the other tests of this participant were included in all the analyses.
In this study the inter-trial reliability and elements of construct validity of the IMU-based wheelchair mobility performance outcomes of four field tests were assessed in elite wheelchair tennis players. The reliability analysis showed good results, with a good reliability on all tests based on the ICC and SEMs, only systematic differences between the two measurement trials for the Illinois test were found. These systematic differences potentially have been caused by a learning effect of the players, thus improving between subsequent tests. As such, it would be best in future use of the Illinois test to familiarize the player with the test by doing extra practice trials or add it as part of previous training sessions, before conducting reliability analyses. The construct validity of the 20m Sprint, Spider test and Illinois test were considered good. The relation between the end times of the different field tests showed a high correlation among all four tests.
The wheelchair tennis field tests are reliable and valid tests to measure the wheelchair mobility performance of wheelchair tennis players. The 20m Sprint as well as the Spider test are recommended to assess the sprinting and manoeuvrability performance in wheelchair tennis athletes, based on the validity, reliability and duration of these tests. With the use of IMUs it is possible to visualize the test execution in detail and gather more detailed information to understand differences between players or monitor a player over time.