London, November 9   : Olympic gold-medal winning heptathlete Jessica Ennis worries that her muscles make her look masculine.

In fact, she thinks her arms look `butch' and thus often covers them up.

In her autobiography, Unbelievable: From My Childhood Dreams to Winning Olympic Gold, she admits she has body hang-ups like many other women.

"I don't look in the mirror and think, Oh God yeah. I don't think I'm anything special," the Daily Mail quoted her as saying.

She admits she avoided weight training when she began competing because "I felt big muscles were unattractive and none of my friends at school had them".

"As a teenage girl I was more self-conscious," she said.

"I would not wear certain things and, to some extent, I am the same now and will usually cover my arms. I look at myself in the mirror and think I am a bit butch, but you get to a point where you finally understand that looks do not matter so much."

Despite her concerns, she has posed for a number of risqué photo shoots, including one in lacy black underwear.

"I did some sexier shots for GQ magazine wearing some hot pants and pouting. I would never do topless or nude pictures or even be body-painted. That is where I draw the line," she said.

Miss Ennis also admitted her irritation at her nickname, Tadpole, which was created by fellow English heptathlete and rival, Kelly Sotherton.

At 5ft 5ins tall, Miss Ennis is often dwarfed by other competitors and she admits that the nickname fuelled her insecurities about her size.

Miss Ennis said: "I knew it wasn't malicious but I also knew there was a slight edge to it. She knew the name would stick and it's not the most flattering."

"The truth is I was hurt by it and did not like it," she added. (ANI)