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Article

Importance of Maximal Strength and Muscle-Tendon Mechanics for Improving Force Steadiness in Persons with Parkinson’s Disease

1
School of Health and Exercise Sciences, University of British Columbia Okanagan, Kelowna, BC V1V1V7 Canada
2
Okanagan Movement Disorders Clinic, Kelowna, BC V1Y1T2, Canada
*
Author to whom correspondence should be addressed.
Brain Sci. 2020, 10(8), 471; https://doi.org/10.3390/brainsci10080471
Received: 19 June 2020 / Revised: 14 July 2020 / Accepted: 18 July 2020 / Published: 22 July 2020
(This article belongs to the Special Issue Brain Plasticity and Motor Control—Series II)
Although plantar flexion force steadiness (FS) is reduced in persons with Parkinson’s disease (PD), the underlying causes are unknown. The aim of this exploratory design study was to ascertain the influence of maximal voluntary contraction (MVC) force and gastrocnemius-Achilles muscle-tendon unit behaviour on FS in persons with PD. Nine persons with PD and nine age- and sex-matched non-PD controls (~70 years, 6 females per group) performed plantar flexion MVCs and sub-maximal tracking tasks at 5, 10, 25, 50 and 75% MVC. Achilles tendon elongation and medial gastrocnemius fascicle lengths were recorded via ultrasound during contraction. FS was quantified using the coefficient of variation (CV) of force. Contributions of MVC and tendon mechanics to FS were determined using multiple regression analyses. Persons with PD were 35% weaker during MVC (p = 0.04) and had 97% greater CV (p = 0.01) with 47% less fascicle shortening (p = 0.004) and 38% less tendon elongation (p = 0.002) than controls. Reduced strength was a direct contributor to lower FS in PD (ß = 0.631), and an indirect factor through limiting optimal muscle-tendon unit interaction. Interestingly, our findings indicate an uncoupling between fascicle shortening and tendon elongation in persons with PD. To better understand limitations in FS and muscle-tendon unit behavior, it is imperative to identify the origins of MVC decrements in persons with PD. View Full-Text
Keywords: ultrasound; muscle fascicle; medial gastrocnemius; Achilles tendon ultrasound; muscle fascicle; medial gastrocnemius; Achilles tendon
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MDPI and ACS Style

Smart, R.R.; Richardson, C.M.; Wile, D.J.; Dalton, B.H.; Jakobi, J.M. Importance of Maximal Strength and Muscle-Tendon Mechanics for Improving Force Steadiness in Persons with Parkinson’s Disease. Brain Sci. 2020, 10, 471. https://doi.org/10.3390/brainsci10080471

AMA Style

Smart RR, Richardson CM, Wile DJ, Dalton BH, Jakobi JM. Importance of Maximal Strength and Muscle-Tendon Mechanics for Improving Force Steadiness in Persons with Parkinson’s Disease. Brain Sciences. 2020; 10(8):471. https://doi.org/10.3390/brainsci10080471

Chicago/Turabian Style

Smart, Rowan R., Cydney M. Richardson, Daryl J. Wile, Brian H. Dalton, and Jennifer M. Jakobi 2020. "Importance of Maximal Strength and Muscle-Tendon Mechanics for Improving Force Steadiness in Persons with Parkinson’s Disease" Brain Sciences 10, no. 8: 471. https://doi.org/10.3390/brainsci10080471

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