For as long as I can remember people have been asking the question, are free weights better than machines when it comes to strength training. Fortunately the answer is simple. Free weights are not better than machines and machines are not better than free weights.
What most people don't realize is that your muscles don't have a brain. In other words, when you ask your muscles to contract (produce force) against an object, they don't know what they are contracting against. They might be contracting against a dumbbell, barbell, kettlebell, machine weight stack, rock, railroad tie, rubber band, tire, your body, etc.
This means that resistance is resistance, no matter where it comes from. When it comes to strength training choose resistance that can be utilized safely and efficiently and you will always win.
Richard J. Wolff, RD, LDN