The squat. The lunge.

They're the meat and potatoes of lower-body strength training, the mainstays of most leg workouts. To the uninitiated, they may seem intimidating -- the type of exercises designed for serious bodybuilders. Actually, they're appropriate for just about anyone who wants to strengthen and tone her legs. And they're practically essential for runners, rowers and other competitive athletes.

They're also safe. Experts have long debated the safety of the squat in particular. However, after reviewing years of research, the National Strength and Conditioning Association has concluded that the squat is not only safe and effective but also is "a significant deterrent to knee injuries." Injuries that result from squat training appear to be caused by poor form and overtraining.