Influences of Change in Muscle Thickness on the Muscle Fiber Contraction Dynamics of Biceps Femoris Long Head During High-Speed Running

• Published in: Baiomekanizumu Gakkai shi Vol. 45; no. 3; pp. 179 - 187
• Main Authors: MIYAZAKI, Terumitsu, FUJII, Norihisa
• Format: Journal Article
• Language: English; Japanese
• Published: Tokyo Society of Biomechanisms 2021; Society of Biomechanisms Japan
• Subjects: Aponeurosis; Hamstring muscle; Hill-type muscle model; Muscle contraction; Musculoskeletal model; Running; Strain injury
• ISSN: 0285-0885
• DOI: 10.3951/sobim.45.3_179

We examined the influences of change in muscle thickness on the muscle fiber contraction dynamics of biceps femoris long head (BFlh) during the late swing phase of high-speed running. Ten male soccer players participated and performed several running trials with their maximal efforts. A musculoskeletal model of the right leg was used to estimate the muscle fiber contraction dynamics such as muscle fiber length, contraction velocity, generation force, and pennation angle. Muscles of the lower limb except BFlh were modeled as a conventional Hill-type muscle model. BFlh was modeled as an applied Hill-type muscle model including several muscle fibers. The model of BFlh was set at two conditions; specifically, the change in muscle thickness with a constant longitudinal cross-sectional area was considered in one model, and constant muscle thickness was considered in another model. In the results, the muscle thickness decreased during the late swing phase of running. The decrease of muscle thickness was a factor for the decrease of the muscle fiber length and pennation angle. Also, the decrease of muscle fiber length affected the normalized force in the muscle fiber force-length relationship. However, the tendency of the variation in muscle fiber generation force between the two conditions in the muscle model was not consistent.