Machines vs free weights: is one better for muscle growth? A new study confirms

Are machines better for building muscle, or are free weights, like dumbbells, superior? It’s a debate that’s as old as the gym itself. There are benefits for both and cons, and now a new (albeit small) study has revealed which comes out on top. Although – spoiler alert – neither is specifically better than the other, so you can chill, gains can be made whichever you have access to.

The study

As we already said, this study published in the Journal of Bodywork and Movement Therapies, was small. It looked at muscle hypertrophy responses in the front thigh muscles , performed using either machines or free weights, in eight untrained women.

The study included eight untrained participants – each person trained their legs either using the inclined leg press machine, or doing lunges using free weights. They did this three times a week over the course of nine weeks.

The results

Ultrasound was used to measure hypertrophy before and after the experiment. This was done at two points in the quads, the rectus femoris (the muscle that runs down the middle of your thigh from your hip bone to your knee caps), and the vastus lateralis (your outer thigh muscle). They measured at two points along each muscle.

The results were pretty straightforward, both free weight and machine training were equally effective at building muscle in women who hadn’t trained before.

Limitations included gender, the small sample size, and the fact that the women included in the study were new to strength training. However, we’ve seen similar results before. For example, this 2023 meta-analysis which looked at 13 studies also reveals that free weights and machines lead to similar results.

Either way, whether you have access to lots of cool machines, or just a rack of dumbbells, you can make significant gains with both. Just remember, the principle of progressive overload is key for hypertrophy. So, whether you only have access to dumbbells, or prefer using a particular machine, you can achieve growth with both.