Exercise Physiology: Theory and Application to Fitness and Performance 9th Edition by Scott Powers, Edward Howley

Exercise 6

Define the term summation.

Step 1 of 2

During a muscle contraction, the muscles respond to the stimuli and produce twitches. Followed by a simple twitch, the muscle relaxes and responds to the next stimulus. However, if the frequency of stimuli increases, the muscles do not have time to relax and the force produced by them to contract becomes additive. Due to this, the force keeps on increasing without relaxation, with addition of successive twitches. This effect is called summation.

In simple terms, the addition of muscle twitches without relaxation of the muscle is called summation.