When it comes to building upper-body strength, machines might give you a little more gain than free weights, but for your legs, both work about the same.

Using weight machines for upper-body workouts might help you get stronger faster than using free weights, but for legs, both methods work about the same—maybe because machines make it easier to focus on the muscles without worrying about balance.

If you lift free weights, you'll get better at lifting free weights. If you use machines, you'll get better at using machines. Practicing the exact same movement makes you better at that movement.

Whether you lift weights the old-fashioned way or use machines, both ways will help you get stronger, build muscle, and jump higher — so you can pick whichever you like better.

If you lift weights with your own body and free weights, you'll get stronger at doing just that — not necessarily at using machines. And if you train mostly on machines, you'll get better at those machines. Your body learns the exact movement you practice.

If you train using weight machines and then test your strength on machines, you’ll get stronger than if you trained with free weights — but only because the test matches the training. It’s like practicing basketball shots from the free-throw line and then being tested there: you’ll do better than if you practiced elsewhere.