Treppe, or the staircase effect, is a phenomenon where a successive increase in amplitude of muscle contractions is witnessed when a number of stimuli with the same strength and intensity are used to excite the neurons, as reported by Drugs.com. The increase in amplitude is basically piggybacking on the increase in temperature, enzyme efficiency, structural elasticity and calcium ion availability that has resulted from the stimuli that happened prior to the each subsequent one. Treppe is also known as the "warm-up effect."
There are three distinct periods for muscle contractions: the latent period, the period of contraction and the period of relaxation.
Muscle contractions are a direct result of the incoming and outgoing flows of different ions, particularly sodium, potassium and calcium, through the ion channels that are found in the muscle cells. As calcium ions enter the cell, they attach to the myofibrils and cause the muscles to begin contracting; however, as the calcium ions lose affinity at the site of attachment, the muscles will begin to relax once again.
There are four different types of muscle contractions. Concentric contractions occur when the muscles are actively shortening. Eccentric contractions occur when the muscles are actively lengthening. Isometric contractions, occur when the muscles are held at a specific position. Length and passive stretches occur when the muscles passively lengthen.