Editor’s note: Dana Santas, known as the “Mobility Maker,” is a certified strength and conditioning specialist and mind-body coach in professional sports, and is the author of the book “Practical ...

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.

The sarcomere is the most basic contractile unit in skeletal and cardiac muscle. Mutations in genes encoding sarcomeric proteins give rise to heritable myopathies, although muscle function is more ...