Olympic heroine Jessica Ennis believes young girls are being put off sport because of worries about the impact on their body shape and being too muscular.
The gold-winning heptathlete said some talented youngsters are wary of training as they fear they will not look the same as their friends.
Ennis told Radio Times that she too was concerned about weight training and had to be reassured by her coach that it would be worth it to win medals.
But the 26-year-old said she has had positive feedback from girls who have shown an interest in athletics as a result of her success.
Ennis told the magazine: "It's important that girls aren't afraid of sport. I remember when I first started doing weight training, I didn't want to be any good at it because I didn't want to be all muscly.
"My coach sat me down and said that if I had more muscles than the average woman, but won an Olympic gold medal, it would be worth it. He was right, but it's hard when you're younger and want to look like everyone else."
She went on: "There's a training group at home in Sheffield and some of the younger girls won't do weights because their friends at school aren't muscly and they don't want to be either. I'm always saying to them that strong can look good. Sport is a good thing."
Ennis suffered unkind mutterings before London 2012 that she had been carrying too much weight. But she proved to critics she was at the top of her game by triumphing, and even completed the 110m hurdle discipline in a record time for the heptathlon.
Ennis is one of five women on the 12-strong shortlist for the BBC Sports Personality of the Year award. Last year there was criticism that the judges failed to recognise achievements of women at all, but this year the likes of rower Katherine Grainger and Ellie Simmonds are on the list.
Ennis said it was important to have positive female role models. She added: "We need more coverage of women's sport, and we need to get women involved in coaching and administration."