When you hear the word contractions, you likely think about the first stages of labor when the uterus tightens and dilates the cervix. But if you’ve been pregnant, you might know that there are many ...

Labor contractions are the physical way your uterus tightens to promote delivery of your baby. All body muscles tighten and shorten (contract) when they’re being used. And the uterus is one of the ...

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.

Jessica Migala has been a health, fitness, and nutrition writer for almost 15 years. She has contributed to more than 40 print and digital publications, including Health and Runner's World. Jessica ...