Sometimes machines can build muscle better—for instance, when you need to isolate specific muscles after an injury, or when you're too inexperienced to perform a free-weight exercise. If you can't complete a pullup, you won't build your back muscles. So do lat pulldowns to develop strength in this range of motion, The real expert says: "Initially, novice athletes will see benefits with either machines or free weights, but as you become more trained, free weights should make up the major portion of your training program, Free-weight exercises mimic athletic moves and generally activate more muscle mass. If you're a seasoned lifter, free weights are your best tools to build strength or burn fat. But is you are a fitness freak without any specific target then Machines are great and this can give you equal power and shape-up..
-- Dr. RANDHIR HASTIR