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Evidence for multi-scale power amplification in skeletal muscle
Jarrod C Petersen1, Thomas J Roberts1
1Department of Ecology, Evolution, and Organismal Biology, Brown University, Providence, RI 02912, USA.
The Journal of Experimental Biology
|September 28, 2023
Summary
Animal power amplification for fast movements involves more than just tendons. Intramuscular tissues and even bone store and release energy, significantly boosting whole-muscle power output beyond simple muscle contractions.
Area of Science:
- Biomechanics
- Muscle Physiology
- Animal Locomotion
Background:
- Animals utilize skeletal muscle and elastic structures for power amplification during rapid movements.
- Tendons are traditionally viewed as the primary elastic springs, but muscles possess internal elastic components at various organizational levels.
Purpose of the Study:
- To quantify power output at different muscle organizational levels.
- To identify the specific locations of power amplification within the muscle-tendon unit and associated structures.
- To investigate the role of intramuscular tissues and external elements in energy storage and release.
Main Methods:
- Utilized ex vivo muscle preparations and high-speed video analysis.
- Compared dynamic ramp-shortening contractions with isotonic power output measurements.
- Quantified force and velocity to calculate power output at fiber, fascicle, muscle belly, and tendon levels.
Main Results:
- Compliant structures outside the muscle-tendon unit, including bone deflection, contributed significantly to peak power (195.22±33.19 W kg-1).
- Intramuscular fascicles generated approximately 1.75 times the maximum isotonic power output (338.78±16.03 W kg-1 vs. 195.23±8.82 W kg-1).
- Both the muscle belly and the muscle-tendon unit demonstrated substantial power amplification.
Conclusions:
- Intramuscular tissues play a crucial role in storing and releasing energy to amplify power output.
- Bone structures can also contribute to power amplification by storing and releasing elastic energy.
- Power amplification in animal locomotion is a complex phenomenon involving multiple biological and structural components.
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