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Measures of motor segmentation from rapid isometric force pulses are reliable and differentiate Parkinson’s disease from age-related slowing

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Abstract

Some people with Parkinson’s disease (PD) have disruptions in motor output during rapid isometric muscle contractions. Measures of such disruptions (motor segmentation) may help clarify disease subtype, progression, or effects of therapeutic interventions. We investigated the potential utility of segmentation measures by testing two hypotheses that are fundamental to measurement and evaluation. First, measures of motor segmentation are reliable from day to day (intraclass correlation coefficient > 0.8). Second, that measures of motor segmentation have the sensitivity to differentiate between people with PD and older adults. 10 subjects with PD had a mean age of 70.1 years, Hoehn–Yahr stage < 3, and median levodopa equivalent daily dose of 350 mg. Older adult (mean age 81.9 years) reference data are from a previously published study. Each subject provided approximately 87 rapid isometric index finger abduction force pulses up to 65% of their maximal isometric force for calculation of force pulse measures. Measures were computed for the excitation, transition, and relaxation phases of each force pulse. Measures of motor segmentation had high reliability and presented large (Cohen’s D > 0.8) and significant (p < 0.05) group differences. In bivariate plots of selected measures, motor segmentation marked a departure of PD from age-related slowing. Across all subjects, greater segmentation was associated with greater impairments in rate control and a longer time to reach peak force (all Spearman’s ρ > 0.8). These results support the potential utility of the motor segmentation measures by satisfying requirements for reliability and the sensitivity to indicate deviations from age-related slowing in motor output.

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The data generated during the current study may be available from the corresponding author on reasonable request.

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Acknowledgements

The authors are grateful for the financial support provided by Shake It Off, Inc. 501(c)3 of West Chester, PA, USA.

Funding

This work was supported by Shake It Off, Inc. 501(c)3 of West Chester, PA, USA.

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Correspondence to Christopher A. Knight.

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The authors have no competing interests to declare that are relevant to the content of this article.

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All study procedures were approved by the University of Delaware Internal Review Board (IRB) and are compliant with the principles for ethical research established by the Declaration of Helsinki.

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Informed consent was obtained from all individual participants included in the study.

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Communicated by Winston D Byblow.

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Howard, S.L., Grenet, D., Bellumori, M. et al. Measures of motor segmentation from rapid isometric force pulses are reliable and differentiate Parkinson’s disease from age-related slowing. Exp Brain Res 240, 2205–2217 (2022). https://doi.org/10.1007/s00221-022-06398-4

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  • DOI: https://doi.org/10.1007/s00221-022-06398-4

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