A stitch.

[ShakeyBurt]

My girlfriend sometimes get a stitch when running. Can anyone tell us what is it? Could she prevent it by eating or drinking something? Or can she do something about it as she is running?

[vittoria]

I remember this happening to me when I was a child. In my case it seemed to happen if I was breathing through my mouth; it stopped happening when I made an effort to breathe through my nose.

[ravenhair]

She needs to warm up properly before she starts running. It's a muscular spasm caused by exercising muscles too suddenly.

[jamesgregory]

I think has somthing to do with lactic acid.