**5. Conclusions**

In conclusion, the K1 and K2 have been shown to be valid and reliable for measuring some aspects of UE and trunk kinematics during reaching. In particular, the K2 exhibited slightly better characteristics for measuring the trunk during standard and extended reaching in di fferent directions, and may be recommended over the K1 in future development for purposes of measuring trunk compensation in clinical populations.

**Author Contributions:** M.H.F. contributed in research design, data collection, data analysis, manuscript development, and manuscript submission. J.R.E. contributed as the research mentor in research supervision and manuscript editing. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research received no external funding.

**Acknowledgments:** This research was supported by the Program in Occupational Therapy at the Washington University School of Medicine. All study participants provided informed consent, and this study was approved by the Institutional Review Board at the Washington University School of Medicine.

**Conflicts of Interest:** The authors have no conflict of interest to declare.
