OBJECTIVES 1. To define these terms used in describing muscle physiology: multiple motor unit summation, maximal stimulus, treppe, wave summation, and tetanus. 2. � To identify two ways that the mode of stimulation can affect muscle force production. 3. � To plot a graph relating stimulus strength and twitch force to illustrate graded muscle response. 4. � To explain how slow, smooth, sustained contraction is possible in a skeletal muscle. 5. � To graphically understand the relationships between passive, active, and total forces. 6. � To identify the conditions under which muscle contraction is isometric or isotonic. 7. � To describe in terms of length and force the transitions between isomet- ric and isotonic conditions during a single muscle twitch. 8. � To describe the effects of resistance and starting length on the initial velocity of shortening. 9. � To explain why muscle force remains constant during isotonic shortening. 10. To explain experimental results in terms of muscle structure.