Stroke Increases Motor Output Variability During Maximal Voluntary Isometric Contractions of Knee Extensor Muscles in Adults

Authors

• Zhilun Zhou, Marquette University
• Stephanie Christine Wolfe, Marquette University
• Brian Schmit, Marquette UniversityFollow
• Matthew J. Durand, Medical College of Wisconsin
• Sandra Hunter, Marquette UniversityFollow
• Allison Hyngstrom, Marquette UniversityFollow

Document Type

Article

Publication Date

3-2026

Publisher

Wiley

Source Publication

Physiological Reports

Source ISSN

2051-817x

Abstract

Greater motor output variability (MOV, inconsistency and unsteadiness) during submaximal tasks post stroke is associated with poorer motor performance. However, little is known about MOV during maximal tasks and relationships with clinical measures of motor performance among stroke survivors. This study determined inconsistency (across discrete attempts) and unsteadiness (within a single attempt) during knee extension maximal voluntary isometric contractions (MVICs) in stroke survivors and neurotypical controls. Forty-three stroke survivors (28 female) and 31 age-matched neurotypical controls (15 female) performed a minimum of five knee extension MVICs with paretic and non-paretic legs (stroke) or dominant leg (controls). Inconsistency was calculated as coefficient of variation between maximal torque values of each MVIC. Unsteadiness was calculated as the average from coefficient of variation of the torque values during each MVIC. The paretic leg of stroke survivors had greater MVIC inconsistency (7.61 ± 4.31% vs. 4.94 ± 2.77%, p = 0.014) and unsteadiness (7.00 ± 3.16% vs. 3.44 ± 1.68%, p <  0.001) than the dominant leg of neurotypical controls. Greater MVIC inconsistency (r_s = −0.374, p = 0.016) and unsteadiness (r_s = −0.445, p = 0.004) of stroke survivors' paretic leg were associated with lower Fugl-Meyer Assessment-Lower Extremity motor scores. Stroke increases MOV during a single session of MVIC measurements with multiple attempts and is associated with poorer clinical measures of motor performance.

Comments

Published version. Physiological Reports, Vol. 14, No. 6 (March 2026). DOI. © 2026 The Physiological Society. Used with permission.

Creative Commons License

This work is licensed under a Creative Commons Attribution 4.0 International License.

Recommended Citation

Zhou, Zhilun; Wolfe, Stephanie Christine; Schmit, Brian; Durand, Matthew J.; Hunter, Sandra; and Hyngstrom, Allison, "Stroke Increases Motor Output Variability During Maximal Voluntary Isometric Contractions of Knee Extensor Muscles in Adults" (2026). Physical Therapy Faculty Research and Publications. 258.
https://epublications.marquette.edu/phys_therapy_fac/258