A long term goal of our laboratory is to characterize how alterations in mechanical load affect cellular mechanisms of muscle contraction. Resistance exercise training is a commonly prescribed modality for altering skeletal muscle function. However, training induced alterations in human muscular strength and performance may be due to changes in neural mechanisms of motor unit recruitment as well as to changes occurring within the muscle per se. Because of the complexity of the human neuromuscular system, it has been difficult to define the specific cellular mechanisms of contraction that are affected by resistance exercise training. We propose using an in vitro, single cell preparation to examine alterations in human skeletal muscle fiber function following 12 weeks of resistance exercise training. Single muscle fibers will be isolated from pre- and post-training vastus lateralis muscle biopsies, chemically skinned to render the sarcolemma permeable to Ca2+, and mounted between a force transducer and servo-controlled position motor. Peak force, maximal shortening velocity, and a force-velocity-power relationship will be determined for each fiber under conditions of maximal Ca2+- activation. Following the physiological experiments, gel electrophoresis will be used to determine the myosin heavy chain and light chain composition of each fiber. The results of this study will provide important insight into the relationships between protein isoform expression and cell function and how these relationships are altered by resistance exercise.

Agency
National Institute of Health (NIH)
Institute
National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS)
Type
Small Research Grants (R03)
Project #
1R03AR046392-01
Application #
6021970
Study Section
Special Emphasis Panel (ZAR1-AAA-A (M1))
Program Officer
Lymn, Richard W
Project Start
1999-09-30
Project End
2001-08-31
Budget Start
1999-09-30
Budget End
2000-08-31
Support Year
1
Fiscal Year
1999
Total Cost
Indirect Cost
Name
Oregon State University
Department
Miscellaneous
Type
Other Domestic Higher Education
DUNS #
053599908
City
Corvallis
State
OR
Country
United States
Zip Code
97339
Widrick, Jeffrey J; Maddalozzo, Gianni F; Lewis, Danielle et al. (2003) Morphological and functional characteristics of skeletal muscle fibers from hormone-replaced and nonreplaced postmenopausal women. J Gerontol A Biol Sci Med Sci 58:3-10
Shoepe, Todd C; Stelzer, Julian E; Garner, Dena P et al. (2003) Functional adaptability of muscle fibers to long-term resistance exercise. Med Sci Sports Exerc 35:944-51
Widrick, Jeffrey J; Stelzer, Julian E; Shoepe, Todd C et al. (2002) Functional properties of human muscle fibers after short-term resistance exercise training. Am J Physiol Regul Integr Comp Physiol 283:R408-16