Caution Using Data from Triaxial Accelerometers Housed in Player Tracking Units During Running

Edwards S., White S., Humphreys S., Robergs R., O’Dwyer N.

Objective: This study aimed to assess the validity and reliability of trunk-mounted accelerometers in estimating thoracic segment or center of gravity (COG) acceleration and vertical ground reaction force (vGRF) during running tasks, while also investigating the potential contribution of an elasticized harness to acceleration overestimation.

Participants: Ten male amateur rugby players were recruited for the study.

Methodology: Participants performed five linear running tasks per lower limb at three different speeds, twice, while wearing two different player tracking units. Triaxial accelerometers were attached laterally to the device on the harness and skin, as well as on both shanks. Three-dimensional data were recorded.

Results: The trunk-mounted accelerometers demonstrated poor reliability (ICC: 0.0–0.67) and high variability (CV%: 14–33%), with changes in mean ranging from 41% to 160%. They were found to be unreliable for estimating vertical acceleration of the COG and thoracic segment, as well as vGRF during running tasks.

Conclusion: Trunk-mounted accelerometers are not valid or reliable for estimating peak vertical acceleration at the thoracic location, whole-body COG acceleration, or vGRF during running. Caution is advised when using data from these accelerometers for player tracking purposes. Improvements in attachment methods and harness materials are needed to enhance the validity and reliability of player tracking instruments.

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