Residual Force Enhancement Is Preserved for Conditions of Reduced Contractile Force
| Autor: | Walter Herzog, Atsuki Fukutani |
|---|---|
| Rok vydání: | 2018 |
| Předmět: |
Sarcomeres
0301 basic medicine Ph level Materials science Steady state biology Muscle Fibers Skeletal Physical Therapy Sports Therapy and Rehabilitation Isometric exercise In Vitro Techniques Sarcomere 03 medical and health sciences 030104 developmental biology 0302 clinical medicine Isometric Contraction biology.protein Biophysics Animals Orthopedics and Sports Medicine Titin Rabbits 030217 neurology & neurosurgery Butanedione monoxime Muscle force |
| Zdroj: | Medicine & Science in Sports & Exercise. 50:1186-1191 |
| ISSN: | 1530-0315 0195-9131 |
| DOI: | 10.1249/mss.0000000000001563 |
| Popis: | INTRODUCTION The isometric muscle force attained after active stretch is greater than that attained in a purely isometric contraction. This property is referred to as residual force enhancement (RFE). Because RFE is thought to be caused by a titin-based passive force, it should be preserved in reduced contractile force states. Therefore, we evaluated the magnitude of RFE in normal and reduced contractile force states. METHODS Skinned fibers of rabbit psoas and soleus (N = 60) were used in all experiments. Reduced contractile force states were induced (i) by using a low Ca concentration (N = 30), (ii) by adding 20 mM butanedione monoxime (N = 15), and (iii) by lowering the pH level (N = 15). Force enhancement and reference isometric tests were conducted for each condition. In the force enhancement tests, fibers were actively stretched from an average sarcomere length of 2.4 to 3.0 μm. The isometric force attained 15 s after the end of stretching was used for analysis. In the isometric reference tests, fibers were activated isometrically at an average sarcomere length of 3.0 μm, and the force at steady state was used for analysis. The absolute and relative magnitudes of RFE were calculated. RESULTS The absolute RFE was the same for the normal and reduced contractile force states. Because the isometric reference force was smaller in the reduced contractile force states, the relative RFE was greater in the reduced contractile force than the normal states for all conditions. CONCLUSION RFE was preserved in the reduced contractile force states. |
| Databáze: | OpenAIRE |
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