A 15-year-old US girl says she has turned "hate into motivation" and ignored her critics to make the switch from cheerleader to football player.

New York resident Ashley Bocek said her aspiration to join the junior varsity football team came during her work as a cheerleader, she told local broadcaster ABC 7 .

"I wanted to be on the football field with them," Ashley said.

"People said I was crazy for playing because I'm not very big. I'm only five-foot-one (154cm tall)."

Ashley said she was required to perform a range of athletic tests before she was allowed to join the team.

The tasks included 40 consecutive push-ups, 57 sit-ups, a flexibility test and a shuttle run.

Ashley noted that many people – including her own family – initially cast doubt on her plan.

She warned that any woman who happened to share her aspirations could expect to face “a lot of hate” along the way.

“But you have to take that hate and turn it into your motivation to prove everyone wrong," she said.

Ashley confirmed she intends to try out for the varsity football squad next year and may undertake wrestling in the off-season to ensure she keeps fit.