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Measurement of Maximum Isometric Force Generated by Permeabilized Skeletal Muscle Fibers
Published on: June 16, 2015
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Force-velocity relationship during isometric and isotonic fatiguing contractions
Andrea N Devrome1, Brian R MacIntosh1
1Faculty of Kinesiology, University of Calgary , Calgary, AB , Canada.
Journal of Applied Physiology (Bethesda, Md. : 1985)
|June 2, 2018
Summary
Fatiguing contractions alter the force-velocity relationship. This study assessed this relationship during continuous isometric and dynamic contractions, revealing distinct changes in maximal velocity (Vmax) and curvature, with incomplete recovery observed.
Area of Science:
- Muscle Physiology
- Exercise Science
- Biomechanics
Background:
- Fatiguing contractions significantly alter muscle force-velocity characteristics.
- Previous assessments often occurred post-contraction, not during sustained fatigue.
Purpose of the Study:
- To determine the force-velocity relationship during steady-state fatigue from both isometric and dynamic contractions.
- To compare the effects of isometric versus dynamic contractions on fatigue development and recovery.
Main Methods:
- Utilized the in situ rat medial gastrocnemius muscle preparation.
- Applied intermittent stimulation (1/s, 170 Hz, 100 ms) to induce fatigue.
- Assessed the force-velocity relationship using the Hill equation during sustained fatigue.
Main Results:
- Both contraction types reduced maximal isometric force and peak power similarly.
- Isotonic contractions caused a greater decrease in maximal shortening velocity (Vmax) compared to isometric contractions.
- The curvature of the force-velocity relationship became less pronounced during fatigue but recovered within 45 minutes.
Conclusions:
- The force-velocity relationship can be accurately determined during maintained fatigue.
- Isotonic contractions induce greater reductions in Vmax than isometric contractions.
- Isometric contractions led to more persistent low-frequency fatigue, potentially due to higher force generation during the fatiguing process.
Keywords:
fatiguelow frequency fatiguemaximal shortening velocitypower-velocity relationshipskeletal muscleMore Related Videos
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