Journal article
In vivo human gracilis muscle active force-length relationship is explained by the sliding filament theory
The Journal of physiology, v 603(10), pp 3049-3059
11 May 2025
PMID: 40349312
Abstract
The sliding filament theory explains skeletal muscle fibre force change as a function of length based on the overlap of actin and myosin filaments. Although this length-tension (LT) relationship has been well investigated in animal models, it is not known whether this microscopic sarcomere LT property can be scaled up five orders of magnitude to explain the LT behaviour of a long human muscle such as the gracilis. The goal of this study is to validate the sarcomere LT curve in humans based on human filament length combined with in vivo experimental data. Intraoperative measurements of maximal tetanic force and muscle-tendon unit length at four different joint configurations (JC) were obtained from 19 patients undergoing free functioning muscle transfer surgery. With physiologically measured fibre length and estimated sarcomere shortening resulting from tendon compliance, we show that 79.7% variance in isometric force data is explained by a simple human sarcomere LT model. This study demonstrates that the human whole muscle LT relationship can be modelled by the sliding filament theory given patient-specific fibre length, filament length, tendon compliance and sarcomere shortening. KEY POINTS: Whole human gracilis muscle isometric length-tension relationships were measured in the operating room. Grouped whole muscle raw length-tension curves showed no obvious form. The width of each experimental length-tension curve was highly variable across subjects and used to predict fibre length (serial sarcomere number). After whole muscle length-tension curves were normalized to each patient's serial sarcomere number, the whole human muscle length-tension curve was well predicted by the sliding filament theory.
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Details
- Title
- In vivo human gracilis muscle active force-length relationship is explained by the sliding filament theory
- Creators
- Zheng Wang - Mayo ClinicLomas S Persad - Mayo Clinic in ArizonaBenjamin I Binder-Markey - Drexel University, Physical Therapy (and Rehabilitation Sciences)Ernest M Hoffman - Mayo ClinicWilliam J Litchy - Mayo Clinic in ArizonaAlexander Y Shin - WinnMedKenton R Kaufman - Mayo Clinic in ArizonaRichard L Lieber - University of California San Diego
- Publication Details
- The Journal of physiology, v 603(10), pp 3049-3059
- Grant note
- I01 RX002462 / RRD VA IK6 RX003351 / RRD VA
- Resource Type
- Journal article
- Language
- English
- Academic Unit
- Physical Therapy (and Rehabilitation Sciences)
- Web of Science ID
- WOS:001484676600001
- Scopus ID
- 2-s2.0-105004768453
- Other Identifier
- 991022053729304721
InCites Highlights
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- Collaboration types
- Domestic collaboration
- Web of Science research areas
- Neurosciences
- Physiology