Inverse dynamics analysis of youth pitching arm kinetics using body composition imaging

Sports Biomech. 2022 Oct;21(9):993-1007. doi: 10.1080/14763141.2020.1715470. Epub 2020 Mar 5.

Abstract

This study's objectives were to: (1) assess whether dual energy X-ray absorptiometry (DXA)-mass inverse dynamics (ID) alters predictions of youth pitching arm kinetics and (2) investigate correlations between kinetics and body composition. Eighteen 10- to 11-year-olds pitched 10 fastballs. DXA scans were conducted to obtain participant-specific upper arm, forearm, and hand masses. Pitching arm segment masses and kinetics calculated with scaled and DXA masses were compared with paired t-tests and correlations were investigated with linear regression. Hand (p < 0.001) and upper arm (p < 0.001) DXA masses were greater, while forearm (p < 0.001) DXA masses were lesser, than their scaled masses. Shoulder compressive force (p < 0.001), internal rotation torque (p < 0.001), and horizontal adduction torque (p = 0.002) increased when using DXA masses. Shoulder compressive force correlated with body mass (p < 0.001) and body mass index (BMI; p = 0.002) and elbow varus torque correlated with body mass (p < 0.05). The main conclusions were that (1) using participant-specific mass ratios leads to different predictions of injury-related pitching arm kinetics and, thus, may improve our understanding of injury risk factors; and (2) pitching arm kinetics were correlated with body composition measures and a relatively high total body mass and/or BMI may increase shoulder and/or elbow injury risk.

Keywords: Baseball; elbow; inverse dynamics; shoulder; throwing.

MeSH terms

  • Adolescent
  • Arm
  • Baseball* / injuries
  • Biomechanical Phenomena
  • Body Composition
  • Elbow Joint*
  • Humans
  • Kinetics
  • Shoulder Joint*
  • Torque