Life Sciences Commons^™

Force-Velocity-Power And Force-Pca Relationships Of Human Soleus Fibers After 17 Days Of Bed Rest, Jeffrey J. Widrick, Kris M. Norenberg, C. A. Blaser, M. Karhanek, Jennifer J. Sherwood, Scott W. Trappe, Todd A. Trappe, David L. Costill, Robert H. Fitts

Biological Sciences Faculty Research and Publications

Soleus muscle fibers from the rat display a reduction in peak power and Ca²⁺ sensitivity after hindlimb suspension. To examine human responses to non-weight bearing, we obtained soleus biopsies from eight adult men before and immediately after 17 days of bed rest (BR). Single chemically skinned fibers were mounted between a force transducer and a servo-controlled position motor and activated with maximal (isotonic properties) and/or submaximal (Ca²⁺ sensitivity) levels of free Ca²⁺. Gel electrophoresis indicated that all pre- and post-BR fibers expressed type I myosin heavy chain. Post-BR fibers obtained from one subject displayed increases in …