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Area of Science:

  • Sports Science
  • Biomechanics
  • Human Movement Analysis

Background:

  • Player tracking devices with accelerometers are used to quantify athletic load, vertical ground reaction force (vGRF), and energy expenditure.
  • Current placement guidelines for these devices are often not followed, potentially compromising data accuracy.

Purpose of the Study:

  • To assess the validity and reliability of trunk-mounted accelerometers for estimating thoracic segment or center of gravity (COG) acceleration and vGRF.
  • To determine if the elasticized harness material contributes to the overestimation of acceleration data.

Main Methods:

  • Ten male amateur rugby players performed linear running tasks at various speeds.
  • Triaxial accelerometers were attached to the trunk harness, skin, and shanks to record 3D data.
  • Data from trunk-mounted devices were compared against accelerations at the thoracic segment, COG, and vGRF.

Main Results:

  • Accelerometers showed poor reliability (ICC: 0.0-0.67) and high variability (CV%: 14-33%).
  • Significant changes in mean values (41-160%) were observed.
  • Trunk-mounted accelerometers were not valid for estimating COG or thoracic segment vertical acceleration, nor vGRF during running.

Conclusions:

  • Caution is advised when using trunk-mounted triaxial accelerometer data for estimating peak vertical acceleration or whole-body COG acceleration/vGRF.
  • Current player tracking instruments require improved attachment methods or harness materials to reduce extraneous acceleration and enhance validity and reliability.