Muscle contraction is the tightening, shortening, or lengthening of muscles when you do some activity. It can happen when you hold or pick up something, or when you stretch or exercise with weights.

Nearly all animals use muscle to move, and it's been known for a long time that muscle, like all other cells, is composed of about 70% water. But researchers don't know what sets the range and ...

Obara, K., et al. (2025). Pharmacological Characteristics of Extracellular Ca2+ Influx Pathways Responsible for Platelet-Activating Factor-Induced Contractions in Rat Esophagus Smooth Muscle ...