From the gurus at http://www.bodybuilding.com…
For some reason, women, their trainers, and advertisers have kidnapped the word “toned” and turned it into the ultimate lady goal. It seems that being muscular is not a goal women should aspire to. Here’s the real deal: You can’t see shape without muscles. You can run on the treadmill or swoosh away on the elliptical all day. Sure, you might get thinner, but without some meat on your delts, triceps, and biceps, you’ll never see those awesome shoulder caps.
Ladies, “I want more muscle,” is an absolutely legitimate goal to tell your trainer or your friends.
On a scientific note, “tone” actually has meaning on a physiological level. Your muscles maintain a low-level contraction, even when you’re at rest. That’s why your muscles are always at least a little firm. This is called “muscle tone,” or “residual muscle tension.” It helps keep you upright, and maintain balance and posture. In this light, there’s really no way to “tone up” your muscles—they’re already toned.