There are athletes and then there are female athletes...
Why is the differentiation needed? In everyday life, it's not. However, in the media female athletes are severely underrepresented and misrepresented, and thus require a separate title than their "superiors." Not only are male athletes pictured and revered considerably more than female athletes, but the way in which they are presented is also skewed. The magazine covers for men and women's fitness magazines differ greatly; men are presented as strong and healthy, while the women's images are sexualized and offer secrets for staying skinny. Let's look at some images to better compare the two.
To the left, the "fit" female is wearing a bikini that is fairly revealing, and certainly not something she would ever workout in. She is flirty-laughing and positioned in a way the is similar to soft-core pornography, as Rowe claims. Meanwhile, the man is completely clothed and positioned in a power stance that shows off his toned biceps. These two images depict a very different version of "fitness."
I remember reading an article in Girl's Life magazine (GL, embarrassing, I know) when I was about 11 years old about how what makeup stays on through sweat, and how to wear my hair in a sporty-cute way. At the time, I played soccer and basketball and could care less about how I looked while doing it. To me, sports were messy and sweaty and I had no problem with that; I remember being confused as to why people would put so much effort into their appearance when the emphasis was (or should have been) on how well they played. At the time I was amused and confused, and certainly didn't read into it until I read the article. However, now it makes perfect (but sad) sense.
Although men are sometimes sexualized in fitness magazines, why do you think it is more common for women to be provocatively posed? Especially since it is generally women who read fitness magazines for females?