title: Concurrent deficits of soleus and gastrocnemius muscle fascicles and Achilles tendon post stroke.
abstract: Calf muscles and Achilles tendon play important roles in functional activities. However, it is not clear how biomechanical properties of the uniarticular soleus (SOL) and biarticular gastrocnemius muscle and Achilles tendon, including the fascicle length, pennation angle, and stiffness, change concurrently post stroke. Biomechanical properties of the medial gastrocnemius (GM) and soleus muscles were evaluated bilaterally in 10 hemiparetic stroke survivors using combined ultrasonography-biomechanical measurements. Biomechanical properties of the Achilles tendon including the length, cross-sectional area (CSA), stiffness, and Young's modulus were evaluated, together with calf muscle biomechanical properties. Gastrocnemius and SOL contributions were separated using flexed and extended knee positions. The impaired side showed decreased fascicle length (GM: 6%, P = 0.002 and SOL: 9%, P = 0.03, at full knee extension and 0° ankle dorsiflexion) and increased fascicular stiffness (GM: 64%, P = 0.005 and SOL: 19%, P = 0.012, at a common 50 N force level). In contrast, Achilles tendon on the impaired side showed changes in the opposite direction as the muscle fascicles with increased tendon length (5%, P < 0.001), decreased tendon CSA (5%, P = 0.04), decreased tendon stiffness (42%, P < 0.001) and Young's modulus (30%, P < 0.001) compared with the unimpaired side. The fascicle and tendon stiffness changes were correlated negatively to the corresponding fascicle and tendon length changes, and decrease in Achilles tendon stiffness was correlated to the increases of SOL and GM fascicular stiffness (P < 0.05). Characterizations of calf muscle fascicles and Achilles tendon biomechanical properties help us better understand concurrent changes of fascicles and tendon as part of the calf muscle-tendon unit and facilitate development of more effective treatments.
authors: Rehabilitation Institute of Chicago, Illinois; Northwestern University, Chicago, Illinois; and Mayo Clinic, Rochester, Minnesota.
authors: Heng
authors: H
authors: Zhao
authors: Rehabilitation Institute of Chicago, Illinois; Northwestern University, Chicago, Illinois; and.
authors: Yupeng
authors: Y
authors: Ren
authors: Rehabilitation Institute of Chicago, Illinois; Northwestern University, Chicago, Illinois; and.
authors: Elliot J
authors: EJ
authors: Roth
authors: Rehabilitation Institute of Chicago, Illinois; Northwestern University, Chicago, Illinois; and.
authors: Richard L
authors: RL
authors: Harvey
authors: Rehabilitation Institute of Chicago, Illinois; Northwestern University, Chicago, Illinois; and l-zhang@northwestern.edu.
authors: Li-Qun
authors: LQ
authors: Zhang
mesh_terms: D000125:Achilles Tendon / Q000000981:diagnostic imaging / Q000503:physiopathology*; D000328:Adult; D000368:Aged; D055119:Elastic Modulus; D006801:Humans; D008297:Male; D008875:Middle Aged; D053580:Muscle Strength; D018482:Muscle, Skeletal / Q000000981:diagnostic imaging / Q000503:physiopathology*; D009135:Muscular Diseases / Q000000981:diagnostic imaging / Q000209:etiology / Q000503:physiopathology*; D020521:Stroke / Q000150:complications / Q000000981:diagnostic imaging / Q000503:physiopathology*; D052256:Tendinopathy / Q000000981:diagnostic imaging / Q000209:etiology / Q000503:physiopathology*; D013718:Tensile Strength; D014463:Ultrasonography
keywords: muscle fascicles; stiffness; stroke; tendon