Free weights are cheaper, burn more calories and exercise a wider range of muscles in the body. On the other hand, weight machines provide more support, are therefore less risky and better for physical therapy. Free weights can be moved freely, such as a dumbbell, barbell, pulley system, medicine ball, ankle weight, or low-row device. Weight machines, on the other hand, are usually only capable of moving in two directions, and include the pec deck.
edit Body Building
Free weights are the better option for building both function and structure, i.e. building visible muscle and creating additional strength. They allow the body to work naturally and are flexible enough for the user to focus on their weaknesses.
Machine weights are able to isolate certain muscles better, and so are good for structural bodybuilding. Resistance machines are also a good choice for beginners because they are supportive, easy to use and save time.
edit Injury Risk
Free weights carry a greater risk of injury, since there is no fixed path for the user, which can lead to misuse and injury. There’s also the risk of dropping the weights. Those using free weights should always work out with a friend or have a “spotter” to assist when working with heavy free weights. Free weight exercise also puts strain on your joints and connective tissues, meaning that correct technique is vital to prevent injury.
As machine weights guide the user, there is less risk of injury, and no need for a spotter. However, because they are designed for the “typical” user, they can force you to move through a harmful range of motion. They can also contribute to injury because they develop superficial muscles but do not develop stabilizer muscles, ligaments and tendons.
edit Calorie Burning
Free weights are significantly cheaper than machine weights. Sporting stores sell free weights by the pound, and they can cost between 10 cents and $1 per pound. Machines can cost from between $600 and several thousand. They are also less space efficient, and several machines are needed to gain a full workout.