Fitness clubs know how to watch their backs, legally speaking. It's nearly impossible to visit a fitness center without signing a waiver that absolves the club of liability -- involving everything from malfunctioning machines that cause injury to improper instruction by staff members. In Michael Stokes' case, it was a defect in the basketball court's floor at his Kent, Wash., gym that caused ruptured tendons in his knee and shoulder. Though a judge found that Stokes may not have known what he was signing, a subsequent appellate-court ruling upheld the waiver and dismissed the case, says Mark Davis, a lawyer who represented Stokes. That's how it usually goes because the majority of states' courts tend to side with the gyms on the matter of liability waivers, while only a handful, including those in New York and Virginia, are likely to rule against them. Occasionally, a judge will rule in behalf of plaintiffs in instances of gross negligence, but that bar is set pretty high in some states, such as Washington, Davis says. Bottom line: Understand that you're taking your health in your own hands when you go to the gym, so you need to watch your own back -- literally.