Question

Compare and contrast wave summation and recruitment mechanisms in permitting the graded contractions of whole muscles. How does the size rule in recruitment affect whole muscle tension development?

Answer 1

Wave summation releases more calcium and increases the force of contraction by increasing the firing rate of motor neurons (The second contraction takes place before the first is completely at rest) so each stimulation adds up. This is all within ONE MUSCLE FIBER. Recruitment is the calling up multiple MOTOR UNITS, in order to increase the force of contraction. t has a size principle (those with small diameters, the more delicate ones are called first, then the larger and so on.) There is no added calcium ions as in wave summation. They usually occur together. wave summation can cause tetanus, while recruitment cannot.