The runner was on a footpath between Redcraig Road and Langton Gardens, in East Calder, around 7pm on Thursday when she was struck from behind.
The thief failed to steal the jogger’s phone – which was strapped to her arm – before making off past Scotmid and a hairdressers on Redcraig Road.
He was white, around 14, approximately 5ft 6ins with a slim build and short dark hair.
He was wearing a dark grey Adidas hooded top, with a large logo on the front and the hood up, black trousers and a black backpack.
Detective Constable Craig Ireland said: “This was a frightening incident and we are looking to trace the male.”