A new study by researchers at Yale and Johns Hopkins University has discovered how asthmatic bronchial spasms — muscle contractions in the airway that cause difficulty breathing in asthma patients— ...

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.

Medically reviewed by Katrina Carter, DPT Key Takeaways Voluntary muscles can be controlled by the person, like muscles in your neck and legs. Involuntary muscles work without you thinking about it, ...