Muscle Percent In Women Book Says Women Have More Leg Strength?

Book says women have more leg strength? - muscle percent in women

Apparently thinking the reason that people understood that more generally, because we are generally larger. But when people have the same size, women are more likely in the legs. I read a book some time ago, and the author says that women have the leg strength of about 6 percent more than men if they have the same size. Ok, I can not believe B / C, I see many young girls in school, with muscular legs. Why only the muscles of the legs and other non-specific as well?

The book is "Myths of Gender: Biological Theories about Women and Men."

Here is the passage:
"The leg strength measured in relation to lean body weight, apart (of the differences in fat) actually shows the legs of women is 5.8 percent more than the people."