The force-length relation of the young adult human tibialis anterior
Background Knowledge 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 tibia...
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PeerJ Inc.
2023-07-01
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| Online Access: | https://peerj.com/articles/15693.pdf |
| _version_ | 1797409403806154752 |
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| author | Brent J. Raiteri Leon Lauret Daniel Hahn |
| author_facet | Brent J. Raiteri Leon Lauret Daniel Hahn |
| author_sort | Brent J. Raiteri |
| collection | DOAJ |
| description | Background Knowledge 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. Methods Participants 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. Results Maximal 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). Discussion TA 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. |
| first_indexed | 2024-03-09T04:14:09Z |
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| institution | Directory Open Access Journal |
| issn | 2167-8359 |
| language | English |
| last_indexed | 2024-03-09T04:14:09Z |
| publishDate | 2023-07-01 |
| publisher | PeerJ Inc. |
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| spelling | doaj.art-887550afc0a94addbe0675b3835704032023-12-03T13:57:09ZengPeerJ Inc.PeerJ2167-83592023-07-0111e1569310.7717/peerj.15693The force-length relation of the young adult human tibialis anteriorBrent J. Raiteri0Leon Lauret1Daniel Hahn2Human Movement Science, Faculty of Sport Science, Ruhr-Universität Bochum, Bochum, Nordrhein-Westfalen, GermanyHuman Movement Science, Faculty of Sport Science, Ruhr-Universität Bochum, Bochum, Nordrhein-Westfalen, GermanyHuman Movement Science, Faculty of Sport Science, Ruhr-Universität Bochum, Bochum, Nordrhein-Westfalen, GermanyBackground Knowledge 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. Methods Participants 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. Results Maximal 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). Discussion TA 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.https://peerj.com/articles/15693.pdfLength-tension relationOptimal lengthDorsiflexorMaximal voluntary contractionTorque-angle relationSkeletal muscle |
| spellingShingle | Brent J. Raiteri Leon Lauret Daniel Hahn The force-length relation of the young adult human tibialis anterior PeerJ Length-tension relation Optimal length Dorsiflexor Maximal voluntary contraction Torque-angle relation Skeletal muscle |
| title | The force-length relation of the young adult human tibialis anterior |
| title_full | The force-length relation of the young adult human tibialis anterior |
| title_fullStr | The force-length relation of the young adult human tibialis anterior |
| title_full_unstemmed | The force-length relation of the young adult human tibialis anterior |
| title_short | The force-length relation of the young adult human tibialis anterior |
| title_sort | force length relation of the young adult human tibialis anterior |
| topic | Length-tension relation Optimal length Dorsiflexor Maximal voluntary contraction Torque-angle relation Skeletal muscle |
| url | https://peerj.com/articles/15693.pdf |
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