Muscle Contraction



- Isometric Contraction:
    - w/ isometric (static) contraction, external muscle length does not change;
    - internally, however, within the fibril the distance between the Z-lines does shortens;
- Isotonic Contraction:
    - is one in which constant internal force is produced, & muscle shortens;
    - it is  also defined as a dynamic exercise with a constant load or resistance;
- Eccentric:
    - contraction is which external force is greater than internal force of the muscle, which causes the muscle to lengthen while continuing to  
          maintain tension;
    - in eccentric contractions, movement is controlled but not initiated;
    - during an eccentric contraction, muscle can sustain greater tension than it can develop in isometric contraction at any given muscle length; 
      - because greater tension is generated, these muscles are more vulnerable to rupture;
- Isokinetic Contraction:
    - term means "constant force" and typically is used to describe dynamic exercise performed through range of motion of joint at constant  
        velocity;
    - equipment used in isokinetic exercises accommodates the exerted force to maintain the specified velocity throughout the arc of motion;
    - because velocity does not change, the kinetic energy remains constant;
    - isokinetic contractions are not part of nl physiologic muscle function



Original Text by Clifford R. Wheeless, III, MD.

Last updated by Data Trace Staff on Monday, December 5, 2011 10:52 am