The force-length relation of the young adult human tibialis anterior

PeerJ

article

Brent J. Raiteri¹  Leon Lauret¹  Daniel Hahn¹ 

[1] Human Movement Science, Faculty of Sport Science, Ruhr-Universität Bochum;School of Human Movement and Nutrition Sciences, University of Queensland

关键词: Length-tension relation;    Optimal length;    Dorsiflexor;    Maximal voluntary contraction;    Torque-angle relation;    Skeletal muscle;    Isometric;    Active force;    Fascicle length;    Musclearchitecture;   

DOI  :  10.7717/peerj.15693

学科分类：社会科学、人文和艺术（综合）

来源: Inra

【 摘 要 】

BackgroundKnowledge of the muscle’s lengths at which maximum active isometric force is attained is important for predicting forces during movement. However, there is limited information about the in vivo force-length properties of a human muscle that plays crucial roles during locomotion; the tibialis anterior (TA). We therefore aimed to estimate TA’s force-length relation from dorsiflexor torque-angle curves constructed from eight women and eight men.MethodsParticipants performed maximal voluntary fixed-end contractions with their right ankle dorsiflexors from 0° to 30° plantar flexion. Muscle fascicle lengths were estimated from B-mode ultrasound images, and net ankle joint torques were measured using dynamometry. Fascicle forces were estimated by dividing maximal active torques by literature-derived, angle-specific tendon moment arm lengths while assuming a fixed 50% force contribution of TA to the total dorsiflexor force and accounting for fascicle angles.ResultsMaximal active torques were higher at 15° than 20° and 30° plantar flexion (2.4–6.4 Nm, p ≤ 0.012), whereas maximal active TA fascicle forces were higher at 15° than 0°, 20° and 30° plantar flexion (25–61 N, p ≤ 0.042), but not different between 15° and 10° plantar flexion (15 N, p = 0.277). TA fascicle shortening magnitudes during fixed-end contractions were larger at 15° than 30° plantar flexion (3.9 mm, p = 0.012), but less at 15° than 0° plantar flexion (−2.4 mm, p = 0.001), with no significant differences (≤0.7 mm, p = 0.871) between TA’s superficial and deep muscle compartments. Series elastic element stiffness was lowest and highest at lengths 5% shorter and 5% longer than optimum fascicle length, respectively (−30 and 15 N/mm, p ≤ 0.003).DiscussionTA produced its maximum active force at 10–15° plantar flexion, and its normalized force-length relation had ascending and descending limbs that agreed with a simple scaled sarcomere model when active fascicle lengths from within TA’s superficial or deep muscle compartment were considered. These findings can be used to inform the properties of the contractile and series elastic elements of Hill-type muscle models.

【 授权许可】

CC BY