Clinical Research

Clinical Intervention

One continuing research interest in our laboratory is the adaptive plasticity of vertebrate skeletal muscle. How does muscle adapt to both the nature and intensity of the demands placed upon it (including those of different sized animals)?  These changes involve changes in metabolic properties such as the densities of capillaries and mitochondria as well as contractile properties such as the force, velocity and efficiency of contraction.  Skeletal muscle is remarkable in part because shifts in very few structural components result in mechanical outcomes as varied as burst power, sound production and posture, to name just a few.

The usual textbook treatment of muscle is to examine the consequences of isometric (constant length) and isotonic (shortening) contractions. However, any time that the force acting on muscle exceeds the force produced by the muscle, it will lengthen, absorbing mechanical work. These “lengthening contractions” have two unique “attributes” that may make this mode of muscle use ideal for some rehabilitation purposes. First, a muscle can produce much more force during a lengthening contraction than during an isometric or shortening one. Second, the amount of energy required per unit force developed is much less. Taken together, these are ideal characteristics for individuals who may be exercise intolerant, yet require an intervention to build muscle mass. Paul LaStayo at the University of Utah and I have investigated the use of chronic eccentric training in frail elderly for whom exercise options are limited. These “clinical” studies done at the University of Arizona, Sarver Heart Center, have shown great promise for individuals with heart failure and respiratory disease. Because these conditions usually limit exercise intensity they tend to be linked to muscle atrophy. Consequently, our eccentric muscle “device” has been patented (by the Arizona Board of Regents) and has led to NAU’s first licensing agreement and launch of a start-up company (Eccentron, LLC).  This is an example of basic science leading directly, though without “plan”, to a novel clinical application.

 

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Other Interests:

Allometry | Energetics | Muscles as Springs