A. Muscle twitch (100msec)1. Latent period (10 msec)Excitation-contraction coupling
2. Contraction period (40msec)Tension/shortening
3. Relaxation period (50msec)Returns to unstimulated tension/length
B. Graded contraction1. All or none responseRefers to the myofiber
2. Multiple motor unit summation = SpatialIndividual motor units combine their activities to increase the contraction of the entire muscle.
3. Muscle toneAt any given time, some fibers are contracted which tightens muscle, but not enough to produce movement
4. Wave summation = TemporalSummation in time, before complete relaxation
a. Incomplete tetanusContraction strength increases in amplitude with partial relaxation
b. Complete tetanusSustained contraction.
5. Asynchronous motor unit summationDifferent motor units are activated at different times
6. TreppeStronger contractions after muscle has contracted several times. "Staircase" phenomenon
7. Isotonic & Isometric contractionsIsotonic - tension develops and it shortens
Isometric - tension develops and it doesn't shorten