TY - JOUR
T1 - Limited fascicle shortening and fascicle rotation may be associated with impaired voluntary force-generating capacity in pennate muscles of chronic stroke survivors
AU - Son, Jongsang
AU - Rymer, William Z.
AU - Lee, Sabrina S.M.
N1 - Publisher Copyright:
© 2020 Elsevier Ltd
PY - 2020/5
Y1 - 2020/5
N2 - Background: Muscle weakness is one of the most common motor impairments after stroke. A variety of progressive muscular changes are reported in chronic stroke survivors, and it is now feasible to consider these changes as an added source of weakness. However, the net contributions of such muscular changes towards muscle weakness have not been fully quantified. Methods: Accordingly, this study aims: (1) to compare muscle architecture of the human medial gastrocnemius between paretic and non-paretic sides in seven chronic hemispheric stroke survivors under passive conditions; (2) to characterize fascicle behavior (i.e., fascicle shortening and fascicle rotation) of the muscle during voluntary isometric contractions; and (3) to assess potential associations between muscle architectural parameters and muscle weakness. Muscle architecture of the medial gastrocnemius (including fascicle length, fascicle pennation angle, and muscle thickness) was characterized using B-mode ultrasonography, and fascicle behavior was then quantified as a function of isometric plantarflexion torque normalized to body mass. Findings: Our experimental results showed that under passive conditions, there was a significant difference in fascicle length and muscle thickness between paretic and non-paretic muscles, but no difference in resting fascicle pennation angle. However, during isometric contraction, both fascicle shortening and fascicle rotation on the paretic side were significantly decreased, compared to the non-paretic side. Moreover, the relative (i.e., paretic/non-paretic) fascicle rotation-shortening ratio (i.e., fascicle rotation per fascicle shortening) was strongly correlated with the relative maximum voluntary isometric plantarflexion torque. Interpretation: This association implies that such fascicle changes could impair the force-generating capacity of the muscle in chronic stroke survivors.
AB - Background: Muscle weakness is one of the most common motor impairments after stroke. A variety of progressive muscular changes are reported in chronic stroke survivors, and it is now feasible to consider these changes as an added source of weakness. However, the net contributions of such muscular changes towards muscle weakness have not been fully quantified. Methods: Accordingly, this study aims: (1) to compare muscle architecture of the human medial gastrocnemius between paretic and non-paretic sides in seven chronic hemispheric stroke survivors under passive conditions; (2) to characterize fascicle behavior (i.e., fascicle shortening and fascicle rotation) of the muscle during voluntary isometric contractions; and (3) to assess potential associations between muscle architectural parameters and muscle weakness. Muscle architecture of the medial gastrocnemius (including fascicle length, fascicle pennation angle, and muscle thickness) was characterized using B-mode ultrasonography, and fascicle behavior was then quantified as a function of isometric plantarflexion torque normalized to body mass. Findings: Our experimental results showed that under passive conditions, there was a significant difference in fascicle length and muscle thickness between paretic and non-paretic muscles, but no difference in resting fascicle pennation angle. However, during isometric contraction, both fascicle shortening and fascicle rotation on the paretic side were significantly decreased, compared to the non-paretic side. Moreover, the relative (i.e., paretic/non-paretic) fascicle rotation-shortening ratio (i.e., fascicle rotation per fascicle shortening) was strongly correlated with the relative maximum voluntary isometric plantarflexion torque. Interpretation: This association implies that such fascicle changes could impair the force-generating capacity of the muscle in chronic stroke survivors.
KW - Fascicle rotation
KW - Fascicle shortening
KW - Muscle mechanics
KW - Muscle weakness
KW - Stroke
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U2 - 10.1016/j.clinbiomech.2020.105007
DO - 10.1016/j.clinbiomech.2020.105007
M3 - Article
C2 - 32339945
AN - SCOPUS:85083565707
SN - 0268-0033
VL - 75
JO - Clinical Biomechanics
JF - Clinical Biomechanics
M1 - 105007
ER -