ROBERT H. FITTS 
Professor and Chair

B.S. 1967, State University of New York-Cortland
M.A. 1969, University of Buffalo
Ph.D. 1972, University of Wisconsin-Madison
Postdoctoral Fellow, Washington University
 
WLS B21
(414) 288-7354
email: robert.fitts@marquette.edu

Click on the Lab Webpage for more information about Dr. Fitts' research program, coursework, and a complete list of publications

Exercise Physiology and Muscle Biology

The laboratory's primary goal is to understand how muscles generate force and elucidate what processes control excitation and contraction (E-C) coupling. In addition to these basic questions, we are evaluating how weightlessness (and models of weightlessness) and fatigue alter muscle function. Finally, we are interested in the effects of regular exercise-training with particular emphasis on its role in preventing the deleterious effects of zero-g and fatigue on skeletal muscle function. We have recently begun to study the role of regular exercise in improving the functional capacity of the whole heart and isolated single myocytes.

Our research effort is directed primarily on three projects: (1) the etiology of muscle fatigue, and (2) the role of high resistance and endurance exercise in improving heart cell function, and (3) the effect of microgravity on the structure-function relationship in skeletal muscle. Currently, we are evaluating the effects of long-term flight aboard the International Space Station. Our goal is to determine the time course of the deleterious alterations in muscle with microgravity so that we can model the expected changes that would occur on a very long duration flight such as a trip to Mars. Related projects are studying the causes of the increased susceptibility to muscle damage (and resulting muscle soreness) that is experienced by all crewmembers post-flight, and work designed to assess the effectiveness of current exercise countermeasures.

Our fatigue studies have centered on 2 processes: 1) the role of excitation-contraction coupling (ECC) in muscle fatigue; and 2) the effect of inorganic phosphate (Pi) and H+ on the force and power production of isolated single fibers. The ECC studies utilize voltage clamped rat fibers to elucidate the cellular causes of a particular type of fatigue know as low frequency fatigue (where force is lost selectively at low frequencies). Preliminary data suggests the main problem involves a disruption of the SR Ca2+ release channel. Our studies on the role of Pi and H+ in muscle fatigue have concentrated on the role of these ions in directly inhibiting the force production of the contracting fiber. Details of our Pi and H+ experiments can be found in a recent publication (see list below).

Selected References:

Fitts, R.H. The Cross-Bridge Cycle and Skeletal Muscle Fatigue.  2008. J. Appl. Physiol. 104: 551-558.

Fitts, R.H., J.G. Romatowski , J.R. Peters, D. Paddon-Jones, R.R. Wolfe , and A.A. Ferrando. 2007. The Deleterious Effects of Bed Rest on Human Skeletal Muscle Fibers are Exacerbated by Hypercortisolemia and Ameliorated by Dietary Supplementation. Am. J. Physiol. Cell Physiol  293: C313-C320.

Knuth, S.T., H. Dave, J.R. Peters, and R.H. Fitts. 2006. Low cell pH depresses peak power in rat skeletal muscle fibres at both 30 and 15 degrees centigrade: Implications for muscle fatigue. J. Physiol. 575: 887-899.

Debold, E.P., J. Romatowski, and R.H. Fitts. 2006. The depressive effect of Pi on the force-calcium relationship in skinned single muscle fibers is temperature dependent. Am. J. Physiol. Cell Physiol. 290: C1041-C1050.

Fitts, R. H. 2003. Effects of regular exercise training on skeletal muscle contractile function. Am. J. Med. Rehabil. 82: 320-330.

Fitts, R.H., Riley, D.R., and J.J. Widrick. 2001. Functional and structural adaptations of skeletal muscle to microgravity. J. Exp. Biol. 204:3201-3208.

Widrick, J.J., Knuth, S.T., Norenberg, K.M., Romatowski, J.G., Bain, J.L.W., Riley, D.A., Karhanek, M., Trappe, S.W., Trappe, T.A., Costil, D.L. and R.H. Fitts. 1999. Effect of a 17 day space-flight on contractile properties of human soleus muscle fibres. J. Physiol. 516:915-930.