What is the term for the 'stair' phenomenon observed when stimulus frequency increases between 10-20 stimuli/second?

The term "treppe," also known as the "staircase effect," refers to a phenomenon observed in muscle contractions where an increasing frequency of stimuli leads to a progressively stronger contraction, typically occurring at stimulus rates between 10-20 stimuli per second. In this context, each successive contraction develops a slightly greater force due to the increased availability of calcium ions in the muscle fibers and a more effective coupling of cross-bridge cycling, which enhances the contractile ability of the muscle.

This phenomenon is significant because it illustrates how muscles can increase their efficiency and strength over a short period of increased stimulation, leading to improved performance and responsiveness. The concept of treppe is particularly important in understanding how skeletal muscles adapt to frequent uses, which can be fundamental in various physical activities and clinical scenarios.