Question

Explain the mechanism responsible for summation of contractions and the increase in height of contraction when the stimulus frequency is increased.

Answer 1

The higher the stimulation frequency, the contractions will be more continuous and even additive.

Continuous stimuli reactivate muscle contraction once the action potential cycle is complete.

Step-by-step explanation:

Muscle contractions can be continuous or cumulative once the action potential curve drops, since the action potential at the top of the mountain is in a refractory period.

I knit a graph of what cumulative contractions are like due to continuous stimulation.

In the graph I leave you pointed out some references:

mr = refractory moment

mnr = non-refractory moment (where the new stimulation is accepted and a more powerful cumulative muscle contraction is generated)

PA = potential for muscle action or contraction itself.