Muscle Physiology: Summation, Treppe, Tetany & Fatigue

Wave Summation

A new stimulus arrives before the muscle fully relaxes, causing contractions to add together and produce greater force.

Treppe Effect

Repeated stimulation causes each contraction to become stronger, even though the muscle fully relaxes between contractions. Also called the staircase effect.

Incomplete Tetany

Rapid stimuli cause sustained muscle contraction with small periods of relaxation between contractions.

Complete Tetany

Stimuli arrive so rapidly that the muscle cannot relax, producing a smooth, continuous contraction.

Tetany

Rapid repeated stimulation causes sustained muscle tension because the muscle cannot fully relax between stimuli.

Muscle Fatigue

The muscle loses its ability to maintain force despite continued stimulation.

Calcium (Ca++)

Calcium allows actin and myosin to interact and generate muscle contractions.

ATP

Provides energy for muscle contraction and relaxation.

Wave Summation vs. Treppe

Wave summation involves incomplete relaxation, while treppe involves full relaxation between contractions.

Incomplete vs. Complete Tetany

Incomplete tetany has small relaxations, while complete tetany has no visible relaxation.