Effects of stroke injury on the shear modulus of the lower leg muscle during passive dorsiflexion
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Nordez, Antoine
Hug, Francois
Andrade, Ricardo
Lecharte, Thomas
McNair, Peter J
Gross, Raphael
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Abstract
Contractures are common complications of a stroke. The spatial location of the increased stiffness among plantar flexors and its variability among survivors remain unknown. This study assessed the mechanical properties of the lower leg muscles in stroke survivors during passive dorsiflexions. Stiffness was estimated through the measurement of the shear modulus. Two experiments were independently conducted, in which participants lay supine: with the knee extended (experiment 1, n = 13 stroke survivors and n = 13 controls), or with the knee flexed at 90° (experiment 2, n = 14 stroke survivors and n = 14 controls). The shear modulus of plantar flexors [gastrocnemius medialis (three locations), gastrocnemius lateralis (three locations), soleus (two locations), flexor digitorum longus, flexor hallucis longus), peroneus longus] and dorsiflexors (tibialis anterior and extensor digitorum longus) was measured using ultrasound shear wave elastography during passive dorsiflexions (2°/s). At the same ankle angle, stroke survivors displayed higher shear modulus than controls for gastrocnemius medialis and gastrocnemius lateralis (knee extended) and soleus (knee flexed). Very low shear modulus was found for the other muscles. The adjustment for muscle slack angle suggested that the increased shear modulus was arising from consequences of contractures. The stiffness distribution between muscles was consistent across participants with the highest shear modulus reported for the most distal regions of gastrocnemius medialis (knee extended) and soleus (knee flexed). These results provide a better appreciation of stiffness locations among plantar flexors of stroke survivors and can provide evidence for the implementation of clinical trials to evaluate targeted interventions applied on these specific muscle regions.
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Journal of Applied Physiology
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126
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1
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Biological sciences
Biomedical and clinical sciences
Science & Technology
Life Sciences & Biomedicine
Physiology
Sport Sciences
contracture
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Le Sant, G; Nordez, A; Hug, F; Andrade, R; Lecharte, T; McNair, PJ; Gross, R, Effects of stroke injury on the shear modulus of the lower leg muscle during passive dorsiflexion, Journal of Applied Physiology, 2019, 126 (1), pp. 11-22