Effects of Mechanical Vibrations and Compression on Muscle Contractile Properties and Physiology

Human movement involves repeated interactions between the body and the environment. In certain cases interaction is presented in the form of impacts between various body parts and a rigid surface. Impacts were shown to induce mechanical vibrations in the tissues. The effects of vibrations on various tissues have been extensively studied in the last four decades and it was found that most tissues react to vibration by means of mechanical and physiological changes. In particular, muscles were shown to respond to vibrations, however, a clear understanding of the physiological and contractile changes occurring in the muscles are not completely elucidated. This thesis proposes to answer some of these questions. Thus, the effects of vibrations on muscle contraction, muscle tissue oxygenation, hemodynamics and contractile properties were studied in selected muscles. It has been found that vibrations have an impact on all these variables and that in certain cases it is desirable to dampen the vibrations induced in the muscles. The most common damping procedure is compression apparel. However, compression is known to have a number of secondary physiological effects. Since these effects might be crucial for the understanding of various apparel interventions on human performance and functioning in general this thesis has also investigated some of the most common phenomena associated with soft tissue compression. Thus, it has been found that compression can selectively improve blood flow, affect the dynamics of local tissue oxygenation and tissue perfusion and might have an effect on metabolites clearance during exercise and/or during the post exercise recovery phase. The findings presented in this thesis show that both mechanical vibrations and the compression associated with damping apparel can have (sometimes surprising) impacts on the basic properties of human skeletal muscles and possibly on the physiology and mechanics of the body as a whole.