Add Yahoo as a preferred source to see more of our stories on Google. A muscle spasm, also known as a cramp, twitch or charley horse, is the sudden and involuntary forced contraction of a muscle.

We are providing an unedited version of this manuscript to give early access to its findings. Before final publication, the manuscript will undergo further editing. Please note there may be errors ...

Struggling to stay steady under pressure may not just be “in your head”; researchers found that mental stress can directly affect muscle blood flow and fine motor control during simple physical tasks.