As remarkable as women's athletic gains have been in recent years--what with their records and achievements inching closer to those of their male counterparts--experts believe that there will always be a gap between the sexes in this area.
"Everything else being equal, say a woman had inherited the same genetic stuff and trained as much, there would still be a 5% to 10% difference in her performance," says Rudy Dressendorfer, professor of human performance and sport at New Mexico Highlands University.
The difference stems mainly from two factors: muscle mass and cardiovascular capacity. And those two factors underlie the speed, strength and endurance so many sports require.
Women are generally smaller than men. But even a woman who is the same size as a man most likely will have less muscle mass because she has a higher percentage of body fat.