Strength training properly can help you develop lean muscle mass thus increasing power, while helping you cut excess fat. You just have to do things right. Strength training can also help you avoid injury. Joint/muscle specific excercises help reduce the rate of injury, or help you recover from a sustained injury like an ACL tear. When used correctly in conjunction, weight training first then cardio, can help you burn more calories translating into more lost weight if you are following a meal plan. Strength training doesn't always encompass gaining massive muscles the football player way. It encompasses weight lifting of all types including women's toning exercises.